From 26a029d407be480d791972afb5975cf62c9360a6 Mon Sep 17 00:00:00 2001
From: Daniel Baumann <daniel.baumann@progress-linux.org>
Date: Fri, 19 Apr 2024 02:47:55 +0200
Subject: Adding upstream version 124.0.1.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
---
 .../css-align/abspos/align-self-htb-ltr-htb.html   | 110 +++++++++++++++
 .../css-align/abspos/align-self-htb-ltr-vlr.html   | 110 +++++++++++++++
 .../css-align/abspos/align-self-htb-ltr-vrl.html   | 110 +++++++++++++++
 .../css-align/abspos/align-self-htb-rtl-htb.html   | 110 +++++++++++++++
 .../css-align/abspos/align-self-htb-rtl-vlr.html   | 110 +++++++++++++++
 .../css-align/abspos/align-self-htb-rtl-vrl.html   | 110 +++++++++++++++
 .../css-align/abspos/align-self-vlr-ltr-htb.html   | 110 +++++++++++++++
 .../css-align/abspos/align-self-vlr-ltr-vlr.html   | 110 +++++++++++++++
 .../css-align/abspos/align-self-vlr-ltr-vrl.html   | 110 +++++++++++++++
 .../css-align/abspos/align-self-vlr-rtl-htb.html   | 110 +++++++++++++++
 .../css-align/abspos/align-self-vlr-rtl-vlr.html   | 110 +++++++++++++++
 .../css-align/abspos/align-self-vlr-rtl-vrl.html   | 110 +++++++++++++++
 .../css-align/abspos/align-self-vrl-ltr-htb.html   | 110 +++++++++++++++
 .../css-align/abspos/align-self-vrl-ltr-vlr.html   | 110 +++++++++++++++
 .../css-align/abspos/align-self-vrl-ltr-vrl.html   | 110 +++++++++++++++
 .../css-align/abspos/align-self-vrl-rtl-htb.html   | 110 +++++++++++++++
 .../css-align/abspos/align-self-vrl-rtl-vlr.html   | 110 +++++++++++++++
 .../css-align/abspos/align-self-vrl-rtl-vrl.html   | 110 +++++++++++++++
 .../css-align/abspos/justify-self-htb-ltr-htb.html | 126 +++++++++++++++++
 .../css-align/abspos/justify-self-htb-ltr-vlr.html | 126 +++++++++++++++++
 .../css-align/abspos/justify-self-htb-ltr-vrl.html | 126 +++++++++++++++++
 .../css-align/abspos/justify-self-htb-rtl-htb.html | 126 +++++++++++++++++
 .../css-align/abspos/justify-self-htb-rtl-vlr.html | 126 +++++++++++++++++
 .../css-align/abspos/justify-self-htb-rtl-vrl.html | 126 +++++++++++++++++
 .../css-align/abspos/justify-self-vlr-ltr-htb.html | 126 +++++++++++++++++
 .../css-align/abspos/justify-self-vlr-ltr-vlr.html | 126 +++++++++++++++++
 .../css-align/abspos/justify-self-vlr-ltr-vrl.html | 126 +++++++++++++++++
 .../css-align/abspos/justify-self-vlr-rtl-htb.html | 126 +++++++++++++++++
 .../css-align/abspos/justify-self-vlr-rtl-vlr.html | 126 +++++++++++++++++
 .../css-align/abspos/justify-self-vlr-rtl-vrl.html | 126 +++++++++++++++++
 .../css-align/abspos/justify-self-vrl-ltr-htb.html | 126 +++++++++++++++++
 .../css-align/abspos/justify-self-vrl-ltr-vlr.html | 126 +++++++++++++++++
 .../css-align/abspos/justify-self-vrl-ltr-vrl.html | 126 +++++++++++++++++
 .../css-align/abspos/justify-self-vrl-rtl-htb.html | 126 +++++++++++++++++
 .../css-align/abspos/justify-self-vrl-rtl-vlr.html | 126 +++++++++++++++++
 .../css-align/abspos/justify-self-vrl-rtl-vrl.html | 126 +++++++++++++++++
 .../css/css-align/abspos/safe-align-self-htb.html  | 149 +++++++++++++++++++++
 .../css/css-align/abspos/safe-align-self-vlr.html  | 149 +++++++++++++++++++++
 .../css/css-align/abspos/safe-align-self-vrl.html  | 149 +++++++++++++++++++++
 .../css-align/abspos/safe-justify-self-htb.html    | 149 +++++++++++++++++++++
 .../css-align/abspos/safe-justify-self-vlr.html    | 149 +++++++++++++++++++++
 .../css-align/abspos/safe-justify-self-vrl.html    | 149 +++++++++++++++++++++
 .../abspos/stretch-intrinsic-size-htb-htb.html     | 100 ++++++++++++++
 .../abspos/stretch-intrinsic-size-htb-vrl.html     | 100 ++++++++++++++
 .../abspos/stretch-intrinsic-size-vrl-htb.html     | 100 ++++++++++++++
 .../abspos/stretch-intrinsic-size-vrl-vrl.html     | 100 ++++++++++++++
 .../css-align/abspos/table-align-self-stretch.html |  84 ++++++++++++
 .../abspos/table-justify-self-stretch.html         |  84 ++++++++++++
 48 files changed, 5710 insertions(+)
 create mode 100644 testing/web-platform/tests/css/css-align/abspos/align-self-htb-ltr-htb.html
 create mode 100644 testing/web-platform/tests/css/css-align/abspos/align-self-htb-ltr-vlr.html
 create mode 100644 testing/web-platform/tests/css/css-align/abspos/align-self-htb-ltr-vrl.html
 create mode 100644 testing/web-platform/tests/css/css-align/abspos/align-self-htb-rtl-htb.html
 create mode 100644 testing/web-platform/tests/css/css-align/abspos/align-self-htb-rtl-vlr.html
 create mode 100644 testing/web-platform/tests/css/css-align/abspos/align-self-htb-rtl-vrl.html
 create mode 100644 testing/web-platform/tests/css/css-align/abspos/align-self-vlr-ltr-htb.html
 create mode 100644 testing/web-platform/tests/css/css-align/abspos/align-self-vlr-ltr-vlr.html
 create mode 100644 testing/web-platform/tests/css/css-align/abspos/align-self-vlr-ltr-vrl.html
 create mode 100644 testing/web-platform/tests/css/css-align/abspos/align-self-vlr-rtl-htb.html
 create mode 100644 testing/web-platform/tests/css/css-align/abspos/align-self-vlr-rtl-vlr.html
 create mode 100644 testing/web-platform/tests/css/css-align/abspos/align-self-vlr-rtl-vrl.html
 create mode 100644 testing/web-platform/tests/css/css-align/abspos/align-self-vrl-ltr-htb.html
 create mode 100644 testing/web-platform/tests/css/css-align/abspos/align-self-vrl-ltr-vlr.html
 create mode 100644 testing/web-platform/tests/css/css-align/abspos/align-self-vrl-ltr-vrl.html
 create mode 100644 testing/web-platform/tests/css/css-align/abspos/align-self-vrl-rtl-htb.html
 create mode 100644 testing/web-platform/tests/css/css-align/abspos/align-self-vrl-rtl-vlr.html
 create mode 100644 testing/web-platform/tests/css/css-align/abspos/align-self-vrl-rtl-vrl.html
 create mode 100644 testing/web-platform/tests/css/css-align/abspos/justify-self-htb-ltr-htb.html
 create mode 100644 testing/web-platform/tests/css/css-align/abspos/justify-self-htb-ltr-vlr.html
 create mode 100644 testing/web-platform/tests/css/css-align/abspos/justify-self-htb-ltr-vrl.html
 create mode 100644 testing/web-platform/tests/css/css-align/abspos/justify-self-htb-rtl-htb.html
 create mode 100644 testing/web-platform/tests/css/css-align/abspos/justify-self-htb-rtl-vlr.html
 create mode 100644 testing/web-platform/tests/css/css-align/abspos/justify-self-htb-rtl-vrl.html
 create mode 100644 testing/web-platform/tests/css/css-align/abspos/justify-self-vlr-ltr-htb.html
 create mode 100644 testing/web-platform/tests/css/css-align/abspos/justify-self-vlr-ltr-vlr.html
 create mode 100644 testing/web-platform/tests/css/css-align/abspos/justify-self-vlr-ltr-vrl.html
 create mode 100644 testing/web-platform/tests/css/css-align/abspos/justify-self-vlr-rtl-htb.html
 create mode 100644 testing/web-platform/tests/css/css-align/abspos/justify-self-vlr-rtl-vlr.html
 create mode 100644 testing/web-platform/tests/css/css-align/abspos/justify-self-vlr-rtl-vrl.html
 create mode 100644 testing/web-platform/tests/css/css-align/abspos/justify-self-vrl-ltr-htb.html
 create mode 100644 testing/web-platform/tests/css/css-align/abspos/justify-self-vrl-ltr-vlr.html
 create mode 100644 testing/web-platform/tests/css/css-align/abspos/justify-self-vrl-ltr-vrl.html
 create mode 100644 testing/web-platform/tests/css/css-align/abspos/justify-self-vrl-rtl-htb.html
 create mode 100644 testing/web-platform/tests/css/css-align/abspos/justify-self-vrl-rtl-vlr.html
 create mode 100644 testing/web-platform/tests/css/css-align/abspos/justify-self-vrl-rtl-vrl.html
 create mode 100644 testing/web-platform/tests/css/css-align/abspos/safe-align-self-htb.html
 create mode 100644 testing/web-platform/tests/css/css-align/abspos/safe-align-self-vlr.html
 create mode 100644 testing/web-platform/tests/css/css-align/abspos/safe-align-self-vrl.html
 create mode 100644 testing/web-platform/tests/css/css-align/abspos/safe-justify-self-htb.html
 create mode 100644 testing/web-platform/tests/css/css-align/abspos/safe-justify-self-vlr.html
 create mode 100644 testing/web-platform/tests/css/css-align/abspos/safe-justify-self-vrl.html
 create mode 100644 testing/web-platform/tests/css/css-align/abspos/stretch-intrinsic-size-htb-htb.html
 create mode 100644 testing/web-platform/tests/css/css-align/abspos/stretch-intrinsic-size-htb-vrl.html
 create mode 100644 testing/web-platform/tests/css/css-align/abspos/stretch-intrinsic-size-vrl-htb.html
 create mode 100644 testing/web-platform/tests/css/css-align/abspos/stretch-intrinsic-size-vrl-vrl.html
 create mode 100644 testing/web-platform/tests/css/css-align/abspos/table-align-self-stretch.html
 create mode 100644 testing/web-platform/tests/css/css-align/abspos/table-justify-self-stretch.html

(limited to 'testing/web-platform/tests/css/css-align/abspos')

diff --git a/testing/web-platform/tests/css/css-align/abspos/align-self-htb-ltr-htb.html b/testing/web-platform/tests/css/css-align/abspos/align-self-htb-ltr-htb.html
new file mode 100644
index 0000000000..786cec7acf
--- /dev/null
+++ b/testing/web-platform/tests/css/css-align/abspos/align-self-htb-ltr-htb.html
@@ -0,0 +1,110 @@
+<!DOCTYPE html>
+<link rel="help" href="https://drafts.csswg.org/css-align-3/#align-abspos">
+<style>
+body {
+  margin: 0;
+}
+
+.container {
+  writing-mode: horizontal-tb;
+  direction: ltr;
+  display: inline-block;
+  position: relative;
+  margin: 20px;
+  border: solid 4px;
+  width: 40px;
+  height: 40px;
+}
+
+.item {
+  writing-mode: horizontal-tb;
+  direction: ltr;
+  position: absolute;
+  background: green;
+  inset: 0;
+}
+
+.item::before {
+  width: 20px;
+  height: 20px;
+  content: '';
+  display: block;
+}
+
+.rtl {
+  direction: rtl;
+}
+</style>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/check-layout-th.js"></script>
+
+<body onload="checkLayout('.item')">
+
+<div class="container">
+  <div class="item" style="align-self: start;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: center;" data-expected-height="20" data-offset-y="10"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: end;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: baseline;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: last baseline;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: self-start;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: self-end;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: stretch;" data-expected-height="40" data-offset-y="0"></div>
+</div>
+
+<!-- RTL -->
+<br>
+
+<div class="container">
+  <div class="item rtl" style="align-self: start;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: center;" data-expected-height="20" data-offset-y="10"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: end;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: baseline;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: last baseline;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: self-start;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: self-end;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: stretch;" data-expected-height="40" data-offset-y="0"></div>
+</div>
+
diff --git a/testing/web-platform/tests/css/css-align/abspos/align-self-htb-ltr-vlr.html b/testing/web-platform/tests/css/css-align/abspos/align-self-htb-ltr-vlr.html
new file mode 100644
index 0000000000..917e50d5e6
--- /dev/null
+++ b/testing/web-platform/tests/css/css-align/abspos/align-self-htb-ltr-vlr.html
@@ -0,0 +1,110 @@
+<!DOCTYPE html>
+<link rel="help" href="https://drafts.csswg.org/css-align-3/#align-abspos">
+<style>
+body {
+  margin: 0;
+}
+
+.container {
+  writing-mode: horizontal-tb;
+  direction: ltr;
+  display: inline-block;
+  position: relative;
+  margin: 20px;
+  border: solid 4px;
+  width: 40px;
+  height: 40px;
+}
+
+.item {
+  writing-mode: vertical-lr;
+  direction: ltr;
+  position: absolute;
+  background: green;
+  inset: 0;
+}
+
+.item::before {
+  width: 20px;
+  height: 20px;
+  content: '';
+  display: block;
+}
+
+.rtl {
+  direction: rtl;
+}
+</style>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/check-layout-th.js"></script>
+
+<body onload="checkLayout('.item')">
+
+<div class="container">
+  <div class="item" style="align-self: start;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: center;" data-expected-height="20" data-offset-y="10"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: end;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: baseline;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: last baseline;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: self-start;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: self-end;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: stretch;" data-expected-height="40" data-offset-y="0"></div>
+</div>
+
+<!-- RTL -->
+<br>
+
+<div class="container">
+  <div class="item rtl" style="align-self: start;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: center;" data-expected-height="20" data-offset-y="10"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: end;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: baseline;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: last baseline;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: self-start;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: self-end;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: stretch;" data-expected-height="40" data-offset-y="0"></div>
+</div>
+
diff --git a/testing/web-platform/tests/css/css-align/abspos/align-self-htb-ltr-vrl.html b/testing/web-platform/tests/css/css-align/abspos/align-self-htb-ltr-vrl.html
new file mode 100644
index 0000000000..b60d461531
--- /dev/null
+++ b/testing/web-platform/tests/css/css-align/abspos/align-self-htb-ltr-vrl.html
@@ -0,0 +1,110 @@
+<!DOCTYPE html>
+<link rel="help" href="https://drafts.csswg.org/css-align-3/#align-abspos">
+<style>
+body {
+  margin: 0;
+}
+
+.container {
+  writing-mode: horizontal-tb;
+  direction: ltr;
+  display: inline-block;
+  position: relative;
+  margin: 20px;
+  border: solid 4px;
+  width: 40px;
+  height: 40px;
+}
+
+.item {
+  writing-mode: vertical-rl;
+  direction: ltr;
+  position: absolute;
+  background: green;
+  inset: 0;
+}
+
+.item::before {
+  width: 20px;
+  height: 20px;
+  content: '';
+  display: block;
+}
+
+.rtl {
+  direction: rtl;
+}
+</style>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/check-layout-th.js"></script>
+
+<body onload="checkLayout('.item')">
+
+<div class="container">
+  <div class="item" style="align-self: start;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: center;" data-expected-height="20" data-offset-y="10"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: end;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: baseline;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: last baseline;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: self-start;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: self-end;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: stretch;" data-expected-height="40" data-offset-y="0"></div>
+</div>
+
+<!-- RTL -->
+<br>
+
+<div class="container">
+  <div class="item rtl" style="align-self: start;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: center;" data-expected-height="20" data-offset-y="10"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: end;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: baseline;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: last baseline;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: self-start;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: self-end;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: stretch;" data-expected-height="40" data-offset-y="0"></div>
+</div>
+
diff --git a/testing/web-platform/tests/css/css-align/abspos/align-self-htb-rtl-htb.html b/testing/web-platform/tests/css/css-align/abspos/align-self-htb-rtl-htb.html
new file mode 100644
index 0000000000..9bf919dd46
--- /dev/null
+++ b/testing/web-platform/tests/css/css-align/abspos/align-self-htb-rtl-htb.html
@@ -0,0 +1,110 @@
+<!DOCTYPE html>
+<link rel="help" href="https://drafts.csswg.org/css-align-3/#align-abspos">
+<style>
+body {
+  margin: 0;
+}
+
+.container {
+  writing-mode: horizontal-tb;
+  direction: rtl;
+  display: inline-block;
+  position: relative;
+  margin: 20px;
+  border: solid 4px;
+  width: 40px;
+  height: 40px;
+}
+
+.item {
+  writing-mode: horizontal-tb;
+  direction: ltr;
+  position: absolute;
+  background: green;
+  inset: 0;
+}
+
+.item::before {
+  width: 20px;
+  height: 20px;
+  content: '';
+  display: block;
+}
+
+.rtl {
+  direction: rtl;
+}
+</style>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/check-layout-th.js"></script>
+
+<body onload="checkLayout('.item')">
+
+<div class="container">
+  <div class="item" style="align-self: start;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: center;" data-expected-height="20" data-offset-y="10"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: end;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: baseline;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: last baseline;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: self-start;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: self-end;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: stretch;" data-expected-height="40" data-offset-y="0"></div>
+</div>
+
+<!-- RTL -->
+<br>
+
+<div class="container">
+  <div class="item rtl" style="align-self: start;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: center;" data-expected-height="20" data-offset-y="10"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: end;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: baseline;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: last baseline;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: self-start;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: self-end;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: stretch;" data-expected-height="40" data-offset-y="0"></div>
+</div>
+
diff --git a/testing/web-platform/tests/css/css-align/abspos/align-self-htb-rtl-vlr.html b/testing/web-platform/tests/css/css-align/abspos/align-self-htb-rtl-vlr.html
new file mode 100644
index 0000000000..5c1e8c75c9
--- /dev/null
+++ b/testing/web-platform/tests/css/css-align/abspos/align-self-htb-rtl-vlr.html
@@ -0,0 +1,110 @@
+<!DOCTYPE html>
+<link rel="help" href="https://drafts.csswg.org/css-align-3/#align-abspos">
+<style>
+body {
+  margin: 0;
+}
+
+.container {
+  writing-mode: horizontal-tb;
+  direction: rtl;
+  display: inline-block;
+  position: relative;
+  margin: 20px;
+  border: solid 4px;
+  width: 40px;
+  height: 40px;
+}
+
+.item {
+  writing-mode: vertical-lr;
+  direction: ltr;
+  position: absolute;
+  background: green;
+  inset: 0;
+}
+
+.item::before {
+  width: 20px;
+  height: 20px;
+  content: '';
+  display: block;
+}
+
+.rtl {
+  direction: rtl;
+}
+</style>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/check-layout-th.js"></script>
+
+<body onload="checkLayout('.item')">
+
+<div class="container">
+  <div class="item" style="align-self: start;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: center;" data-expected-height="20" data-offset-y="10"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: end;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: baseline;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: last baseline;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: self-start;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: self-end;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: stretch;" data-expected-height="40" data-offset-y="0"></div>
+</div>
+
+<!-- RTL -->
+<br>
+
+<div class="container">
+  <div class="item rtl" style="align-self: start;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: center;" data-expected-height="20" data-offset-y="10"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: end;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: baseline;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: last baseline;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: self-start;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: self-end;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: stretch;" data-expected-height="40" data-offset-y="0"></div>
+</div>
+
diff --git a/testing/web-platform/tests/css/css-align/abspos/align-self-htb-rtl-vrl.html b/testing/web-platform/tests/css/css-align/abspos/align-self-htb-rtl-vrl.html
new file mode 100644
index 0000000000..b7f0056976
--- /dev/null
+++ b/testing/web-platform/tests/css/css-align/abspos/align-self-htb-rtl-vrl.html
@@ -0,0 +1,110 @@
+<!DOCTYPE html>
+<link rel="help" href="https://drafts.csswg.org/css-align-3/#align-abspos">
+<style>
+body {
+  margin: 0;
+}
+
+.container {
+  writing-mode: horizontal-tb;
+  direction: rtl;
+  display: inline-block;
+  position: relative;
+  margin: 20px;
+  border: solid 4px;
+  width: 40px;
+  height: 40px;
+}
+
+.item {
+  writing-mode: vertical-rl;
+  direction: ltr;
+  position: absolute;
+  background: green;
+  inset: 0;
+}
+
+.item::before {
+  width: 20px;
+  height: 20px;
+  content: '';
+  display: block;
+}
+
+.rtl {
+  direction: rtl;
+}
+</style>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/check-layout-th.js"></script>
+
+<body onload="checkLayout('.item')">
+
+<div class="container">
+  <div class="item" style="align-self: start;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: center;" data-expected-height="20" data-offset-y="10"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: end;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: baseline;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: last baseline;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: self-start;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: self-end;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: stretch;" data-expected-height="40" data-offset-y="0"></div>
+</div>
+
+<!-- RTL -->
+<br>
+
+<div class="container">
+  <div class="item rtl" style="align-self: start;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: center;" data-expected-height="20" data-offset-y="10"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: end;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: baseline;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: last baseline;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: self-start;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: self-end;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: stretch;" data-expected-height="40" data-offset-y="0"></div>
+</div>
+
diff --git a/testing/web-platform/tests/css/css-align/abspos/align-self-vlr-ltr-htb.html b/testing/web-platform/tests/css/css-align/abspos/align-self-vlr-ltr-htb.html
new file mode 100644
index 0000000000..98e3c0b936
--- /dev/null
+++ b/testing/web-platform/tests/css/css-align/abspos/align-self-vlr-ltr-htb.html
@@ -0,0 +1,110 @@
+<!DOCTYPE html>
+<link rel="help" href="https://drafts.csswg.org/css-align-3/#align-abspos">
+<style>
+body {
+  margin: 0;
+}
+
+.container {
+  writing-mode: vertical-lr;
+  direction: ltr;
+  display: inline-block;
+  position: relative;
+  margin: 20px;
+  border: solid 4px;
+  width: 40px;
+  height: 40px;
+}
+
+.item {
+  writing-mode: horizontal-tb;
+  direction: ltr;
+  position: absolute;
+  background: green;
+  inset: 0;
+}
+
+.item::before {
+  width: 20px;
+  height: 20px;
+  content: '';
+  display: block;
+}
+
+.rtl {
+  direction: rtl;
+}
+</style>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/check-layout-th.js"></script>
+
+<body onload="checkLayout('.item')">
+
+<div class="container">
+  <div class="item" style="align-self: start;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: center;" data-expected-width="20" data-offset-x="10"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: end;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: baseline;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: last baseline;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: self-start;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: self-end;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: stretch;" data-expected-width="40" data-offset-x="0"></div>
+</div>
+
+<!-- RTL -->
+<br>
+
+<div class="container">
+  <div class="item rtl" style="align-self: start;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: center;" data-expected-width="20" data-offset-x="10"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: end;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: baseline;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: last baseline;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: self-start;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: self-end;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: stretch;" data-expected-width="40" data-offset-x="0"></div>
+</div>
+
diff --git a/testing/web-platform/tests/css/css-align/abspos/align-self-vlr-ltr-vlr.html b/testing/web-platform/tests/css/css-align/abspos/align-self-vlr-ltr-vlr.html
new file mode 100644
index 0000000000..73585d2db5
--- /dev/null
+++ b/testing/web-platform/tests/css/css-align/abspos/align-self-vlr-ltr-vlr.html
@@ -0,0 +1,110 @@
+<!DOCTYPE html>
+<link rel="help" href="https://drafts.csswg.org/css-align-3/#align-abspos">
+<style>
+body {
+  margin: 0;
+}
+
+.container {
+  writing-mode: vertical-lr;
+  direction: ltr;
+  display: inline-block;
+  position: relative;
+  margin: 20px;
+  border: solid 4px;
+  width: 40px;
+  height: 40px;
+}
+
+.item {
+  writing-mode: vertical-lr;
+  direction: ltr;
+  position: absolute;
+  background: green;
+  inset: 0;
+}
+
+.item::before {
+  width: 20px;
+  height: 20px;
+  content: '';
+  display: block;
+}
+
+.rtl {
+  direction: rtl;
+}
+</style>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/check-layout-th.js"></script>
+
+<body onload="checkLayout('.item')">
+
+<div class="container">
+  <div class="item" style="align-self: start;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: center;" data-expected-width="20" data-offset-x="10"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: end;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: baseline;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: last baseline;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: self-start;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: self-end;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: stretch;" data-expected-width="40" data-offset-x="0"></div>
+</div>
+
+<!-- RTL -->
+<br>
+
+<div class="container">
+  <div class="item rtl" style="align-self: start;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: center;" data-expected-width="20" data-offset-x="10"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: end;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: baseline;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: last baseline;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: self-start;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: self-end;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: stretch;" data-expected-width="40" data-offset-x="0"></div>
+</div>
+
diff --git a/testing/web-platform/tests/css/css-align/abspos/align-self-vlr-ltr-vrl.html b/testing/web-platform/tests/css/css-align/abspos/align-self-vlr-ltr-vrl.html
new file mode 100644
index 0000000000..39ecd38899
--- /dev/null
+++ b/testing/web-platform/tests/css/css-align/abspos/align-self-vlr-ltr-vrl.html
@@ -0,0 +1,110 @@
+<!DOCTYPE html>
+<link rel="help" href="https://drafts.csswg.org/css-align-3/#align-abspos">
+<style>
+body {
+  margin: 0;
+}
+
+.container {
+  writing-mode: vertical-lr;
+  direction: ltr;
+  display: inline-block;
+  position: relative;
+  margin: 20px;
+  border: solid 4px;
+  width: 40px;
+  height: 40px;
+}
+
+.item {
+  writing-mode: vertical-rl;
+  direction: ltr;
+  position: absolute;
+  background: green;
+  inset: 0;
+}
+
+.item::before {
+  width: 20px;
+  height: 20px;
+  content: '';
+  display: block;
+}
+
+.rtl {
+  direction: rtl;
+}
+</style>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/check-layout-th.js"></script>
+
+<body onload="checkLayout('.item')">
+
+<div class="container">
+  <div class="item" style="align-self: start;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: center;" data-expected-width="20" data-offset-x="10"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: end;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: baseline;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: last baseline;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: self-start;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: self-end;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: stretch;" data-expected-width="40" data-offset-x="0"></div>
+</div>
+
+<!-- RTL -->
+<br>
+
+<div class="container">
+  <div class="item rtl" style="align-self: start;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: center;" data-expected-width="20" data-offset-x="10"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: end;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: baseline;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: last baseline;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: self-start;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: self-end;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: stretch;" data-expected-width="40" data-offset-x="0"></div>
+</div>
+
diff --git a/testing/web-platform/tests/css/css-align/abspos/align-self-vlr-rtl-htb.html b/testing/web-platform/tests/css/css-align/abspos/align-self-vlr-rtl-htb.html
new file mode 100644
index 0000000000..7a4167f62a
--- /dev/null
+++ b/testing/web-platform/tests/css/css-align/abspos/align-self-vlr-rtl-htb.html
@@ -0,0 +1,110 @@
+<!DOCTYPE html>
+<link rel="help" href="https://drafts.csswg.org/css-align-3/#align-abspos">
+<style>
+body {
+  margin: 0;
+}
+
+.container {
+  writing-mode: vertical-lr;
+  direction: rtl;
+  display: inline-block;
+  position: relative;
+  margin: 20px;
+  border: solid 4px;
+  width: 40px;
+  height: 40px;
+}
+
+.item {
+  writing-mode: horizontal-tb;
+  direction: ltr;
+  position: absolute;
+  background: green;
+  inset: 0;
+}
+
+.item::before {
+  width: 20px;
+  height: 20px;
+  content: '';
+  display: block;
+}
+
+.rtl {
+  direction: rtl;
+}
+</style>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/check-layout-th.js"></script>
+
+<body onload="checkLayout('.item')">
+
+<div class="container">
+  <div class="item" style="align-self: start;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: center;" data-expected-width="20" data-offset-x="10"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: end;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: baseline;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: last baseline;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: self-start;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: self-end;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: stretch;" data-expected-width="40" data-offset-x="0"></div>
+</div>
+
+<!-- RTL -->
+<br>
+
+<div class="container">
+  <div class="item rtl" style="align-self: start;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: center;" data-expected-width="20" data-offset-x="10"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: end;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: baseline;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: last baseline;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: self-start;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: self-end;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: stretch;" data-expected-width="40" data-offset-x="0"></div>
+</div>
+
diff --git a/testing/web-platform/tests/css/css-align/abspos/align-self-vlr-rtl-vlr.html b/testing/web-platform/tests/css/css-align/abspos/align-self-vlr-rtl-vlr.html
new file mode 100644
index 0000000000..4ce7d46520
--- /dev/null
+++ b/testing/web-platform/tests/css/css-align/abspos/align-self-vlr-rtl-vlr.html
@@ -0,0 +1,110 @@
+<!DOCTYPE html>
+<link rel="help" href="https://drafts.csswg.org/css-align-3/#align-abspos">
+<style>
+body {
+  margin: 0;
+}
+
+.container {
+  writing-mode: vertical-lr;
+  direction: rtl;
+  display: inline-block;
+  position: relative;
+  margin: 20px;
+  border: solid 4px;
+  width: 40px;
+  height: 40px;
+}
+
+.item {
+  writing-mode: vertical-lr;
+  direction: ltr;
+  position: absolute;
+  background: green;
+  inset: 0;
+}
+
+.item::before {
+  width: 20px;
+  height: 20px;
+  content: '';
+  display: block;
+}
+
+.rtl {
+  direction: rtl;
+}
+</style>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/check-layout-th.js"></script>
+
+<body onload="checkLayout('.item')">
+
+<div class="container">
+  <div class="item" style="align-self: start;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: center;" data-expected-width="20" data-offset-x="10"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: end;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: baseline;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: last baseline;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: self-start;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: self-end;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: stretch;" data-expected-width="40" data-offset-x="0"></div>
+</div>
+
+<!-- RTL -->
+<br>
+
+<div class="container">
+  <div class="item rtl" style="align-self: start;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: center;" data-expected-width="20" data-offset-x="10"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: end;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: baseline;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: last baseline;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: self-start;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: self-end;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: stretch;" data-expected-width="40" data-offset-x="0"></div>
+</div>
+
diff --git a/testing/web-platform/tests/css/css-align/abspos/align-self-vlr-rtl-vrl.html b/testing/web-platform/tests/css/css-align/abspos/align-self-vlr-rtl-vrl.html
new file mode 100644
index 0000000000..0fe160442f
--- /dev/null
+++ b/testing/web-platform/tests/css/css-align/abspos/align-self-vlr-rtl-vrl.html
@@ -0,0 +1,110 @@
+<!DOCTYPE html>
+<link rel="help" href="https://drafts.csswg.org/css-align-3/#align-abspos">
+<style>
+body {
+  margin: 0;
+}
+
+.container {
+  writing-mode: vertical-lr;
+  direction: rtl;
+  display: inline-block;
+  position: relative;
+  margin: 20px;
+  border: solid 4px;
+  width: 40px;
+  height: 40px;
+}
+
+.item {
+  writing-mode: vertical-rl;
+  direction: ltr;
+  position: absolute;
+  background: green;
+  inset: 0;
+}
+
+.item::before {
+  width: 20px;
+  height: 20px;
+  content: '';
+  display: block;
+}
+
+.rtl {
+  direction: rtl;
+}
+</style>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/check-layout-th.js"></script>
+
+<body onload="checkLayout('.item')">
+
+<div class="container">
+  <div class="item" style="align-self: start;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: center;" data-expected-width="20" data-offset-x="10"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: end;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: baseline;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: last baseline;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: self-start;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: self-end;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: stretch;" data-expected-width="40" data-offset-x="0"></div>
+</div>
+
+<!-- RTL -->
+<br>
+
+<div class="container">
+  <div class="item rtl" style="align-self: start;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: center;" data-expected-width="20" data-offset-x="10"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: end;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: baseline;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: last baseline;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: self-start;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: self-end;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: stretch;" data-expected-width="40" data-offset-x="0"></div>
+</div>
+
diff --git a/testing/web-platform/tests/css/css-align/abspos/align-self-vrl-ltr-htb.html b/testing/web-platform/tests/css/css-align/abspos/align-self-vrl-ltr-htb.html
new file mode 100644
index 0000000000..98e6145a63
--- /dev/null
+++ b/testing/web-platform/tests/css/css-align/abspos/align-self-vrl-ltr-htb.html
@@ -0,0 +1,110 @@
+<!DOCTYPE html>
+<link rel="help" href="https://drafts.csswg.org/css-align-3/#align-abspos">
+<style>
+body {
+  margin: 0;
+}
+
+.container {
+  writing-mode: vertical-rl;
+  direction: ltr;
+  display: inline-block;
+  position: relative;
+  margin: 20px;
+  border: solid 4px;
+  width: 40px;
+  height: 40px;
+}
+
+.item {
+  writing-mode: horizontal-tb;
+  direction: ltr;
+  position: absolute;
+  background: green;
+  inset: 0;
+}
+
+.item::before {
+  width: 20px;
+  height: 20px;
+  content: '';
+  display: block;
+}
+
+.rtl {
+  direction: rtl;
+}
+</style>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/check-layout-th.js"></script>
+
+<body onload="checkLayout('.item')">
+
+<div class="container">
+  <div class="item" style="align-self: start;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: center;" data-expected-width="20" data-offset-x="10"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: end;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: baseline;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: last baseline;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: self-start;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: self-end;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: stretch;" data-expected-width="40" data-offset-x="0"></div>
+</div>
+
+<!-- RTL -->
+<br>
+
+<div class="container">
+  <div class="item rtl" style="align-self: start;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: center;" data-expected-width="20" data-offset-x="10"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: end;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: baseline;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: last baseline;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: self-start;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: self-end;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: stretch;" data-expected-width="40" data-offset-x="0"></div>
+</div>
+
diff --git a/testing/web-platform/tests/css/css-align/abspos/align-self-vrl-ltr-vlr.html b/testing/web-platform/tests/css/css-align/abspos/align-self-vrl-ltr-vlr.html
new file mode 100644
index 0000000000..d22b347da3
--- /dev/null
+++ b/testing/web-platform/tests/css/css-align/abspos/align-self-vrl-ltr-vlr.html
@@ -0,0 +1,110 @@
+<!DOCTYPE html>
+<link rel="help" href="https://drafts.csswg.org/css-align-3/#align-abspos">
+<style>
+body {
+  margin: 0;
+}
+
+.container {
+  writing-mode: vertical-rl;
+  direction: ltr;
+  display: inline-block;
+  position: relative;
+  margin: 20px;
+  border: solid 4px;
+  width: 40px;
+  height: 40px;
+}
+
+.item {
+  writing-mode: vertical-lr;
+  direction: ltr;
+  position: absolute;
+  background: green;
+  inset: 0;
+}
+
+.item::before {
+  width: 20px;
+  height: 20px;
+  content: '';
+  display: block;
+}
+
+.rtl {
+  direction: rtl;
+}
+</style>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/check-layout-th.js"></script>
+
+<body onload="checkLayout('.item')">
+
+<div class="container">
+  <div class="item" style="align-self: start;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: center;" data-expected-width="20" data-offset-x="10"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: end;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: baseline;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: last baseline;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: self-start;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: self-end;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: stretch;" data-expected-width="40" data-offset-x="0"></div>
+</div>
+
+<!-- RTL -->
+<br>
+
+<div class="container">
+  <div class="item rtl" style="align-self: start;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: center;" data-expected-width="20" data-offset-x="10"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: end;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: baseline;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: last baseline;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: self-start;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: self-end;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: stretch;" data-expected-width="40" data-offset-x="0"></div>
+</div>
+
diff --git a/testing/web-platform/tests/css/css-align/abspos/align-self-vrl-ltr-vrl.html b/testing/web-platform/tests/css/css-align/abspos/align-self-vrl-ltr-vrl.html
new file mode 100644
index 0000000000..602b7afb7b
--- /dev/null
+++ b/testing/web-platform/tests/css/css-align/abspos/align-self-vrl-ltr-vrl.html
@@ -0,0 +1,110 @@
+<!DOCTYPE html>
+<link rel="help" href="https://drafts.csswg.org/css-align-3/#align-abspos">
+<style>
+body {
+  margin: 0;
+}
+
+.container {
+  writing-mode: vertical-rl;
+  direction: ltr;
+  display: inline-block;
+  position: relative;
+  margin: 20px;
+  border: solid 4px;
+  width: 40px;
+  height: 40px;
+}
+
+.item {
+  writing-mode: vertical-rl;
+  direction: ltr;
+  position: absolute;
+  background: green;
+  inset: 0;
+}
+
+.item::before {
+  width: 20px;
+  height: 20px;
+  content: '';
+  display: block;
+}
+
+.rtl {
+  direction: rtl;
+}
+</style>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/check-layout-th.js"></script>
+
+<body onload="checkLayout('.item')">
+
+<div class="container">
+  <div class="item" style="align-self: start;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: center;" data-expected-width="20" data-offset-x="10"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: end;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: baseline;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: last baseline;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: self-start;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: self-end;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: stretch;" data-expected-width="40" data-offset-x="0"></div>
+</div>
+
+<!-- RTL -->
+<br>
+
+<div class="container">
+  <div class="item rtl" style="align-self: start;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: center;" data-expected-width="20" data-offset-x="10"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: end;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: baseline;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: last baseline;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: self-start;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: self-end;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: stretch;" data-expected-width="40" data-offset-x="0"></div>
+</div>
+
diff --git a/testing/web-platform/tests/css/css-align/abspos/align-self-vrl-rtl-htb.html b/testing/web-platform/tests/css/css-align/abspos/align-self-vrl-rtl-htb.html
new file mode 100644
index 0000000000..1dcfd8709f
--- /dev/null
+++ b/testing/web-platform/tests/css/css-align/abspos/align-self-vrl-rtl-htb.html
@@ -0,0 +1,110 @@
+<!DOCTYPE html>
+<link rel="help" href="https://drafts.csswg.org/css-align-3/#align-abspos">
+<style>
+body {
+  margin: 0;
+}
+
+.container {
+  writing-mode: vertical-rl;
+  direction: rtl;
+  display: inline-block;
+  position: relative;
+  margin: 20px;
+  border: solid 4px;
+  width: 40px;
+  height: 40px;
+}
+
+.item {
+  writing-mode: horizontal-tb;
+  direction: ltr;
+  position: absolute;
+  background: green;
+  inset: 0;
+}
+
+.item::before {
+  width: 20px;
+  height: 20px;
+  content: '';
+  display: block;
+}
+
+.rtl {
+  direction: rtl;
+}
+</style>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/check-layout-th.js"></script>
+
+<body onload="checkLayout('.item')">
+
+<div class="container">
+  <div class="item" style="align-self: start;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: center;" data-expected-width="20" data-offset-x="10"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: end;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: baseline;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: last baseline;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: self-start;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: self-end;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: stretch;" data-expected-width="40" data-offset-x="0"></div>
+</div>
+
+<!-- RTL -->
+<br>
+
+<div class="container">
+  <div class="item rtl" style="align-self: start;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: center;" data-expected-width="20" data-offset-x="10"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: end;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: baseline;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: last baseline;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: self-start;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: self-end;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: stretch;" data-expected-width="40" data-offset-x="0"></div>
+</div>
+
diff --git a/testing/web-platform/tests/css/css-align/abspos/align-self-vrl-rtl-vlr.html b/testing/web-platform/tests/css/css-align/abspos/align-self-vrl-rtl-vlr.html
new file mode 100644
index 0000000000..d22b347da3
--- /dev/null
+++ b/testing/web-platform/tests/css/css-align/abspos/align-self-vrl-rtl-vlr.html
@@ -0,0 +1,110 @@
+<!DOCTYPE html>
+<link rel="help" href="https://drafts.csswg.org/css-align-3/#align-abspos">
+<style>
+body {
+  margin: 0;
+}
+
+.container {
+  writing-mode: vertical-rl;
+  direction: ltr;
+  display: inline-block;
+  position: relative;
+  margin: 20px;
+  border: solid 4px;
+  width: 40px;
+  height: 40px;
+}
+
+.item {
+  writing-mode: vertical-lr;
+  direction: ltr;
+  position: absolute;
+  background: green;
+  inset: 0;
+}
+
+.item::before {
+  width: 20px;
+  height: 20px;
+  content: '';
+  display: block;
+}
+
+.rtl {
+  direction: rtl;
+}
+</style>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/check-layout-th.js"></script>
+
+<body onload="checkLayout('.item')">
+
+<div class="container">
+  <div class="item" style="align-self: start;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: center;" data-expected-width="20" data-offset-x="10"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: end;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: baseline;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: last baseline;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: self-start;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: self-end;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: stretch;" data-expected-width="40" data-offset-x="0"></div>
+</div>
+
+<!-- RTL -->
+<br>
+
+<div class="container">
+  <div class="item rtl" style="align-self: start;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: center;" data-expected-width="20" data-offset-x="10"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: end;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: baseline;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: last baseline;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: self-start;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: self-end;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: stretch;" data-expected-width="40" data-offset-x="0"></div>
+</div>
+
diff --git a/testing/web-platform/tests/css/css-align/abspos/align-self-vrl-rtl-vrl.html b/testing/web-platform/tests/css/css-align/abspos/align-self-vrl-rtl-vrl.html
new file mode 100644
index 0000000000..602b7afb7b
--- /dev/null
+++ b/testing/web-platform/tests/css/css-align/abspos/align-self-vrl-rtl-vrl.html
@@ -0,0 +1,110 @@
+<!DOCTYPE html>
+<link rel="help" href="https://drafts.csswg.org/css-align-3/#align-abspos">
+<style>
+body {
+  margin: 0;
+}
+
+.container {
+  writing-mode: vertical-rl;
+  direction: ltr;
+  display: inline-block;
+  position: relative;
+  margin: 20px;
+  border: solid 4px;
+  width: 40px;
+  height: 40px;
+}
+
+.item {
+  writing-mode: vertical-rl;
+  direction: ltr;
+  position: absolute;
+  background: green;
+  inset: 0;
+}
+
+.item::before {
+  width: 20px;
+  height: 20px;
+  content: '';
+  display: block;
+}
+
+.rtl {
+  direction: rtl;
+}
+</style>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/check-layout-th.js"></script>
+
+<body onload="checkLayout('.item')">
+
+<div class="container">
+  <div class="item" style="align-self: start;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: center;" data-expected-width="20" data-offset-x="10"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: end;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: baseline;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: last baseline;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: self-start;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: self-end;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="align-self: stretch;" data-expected-width="40" data-offset-x="0"></div>
+</div>
+
+<!-- RTL -->
+<br>
+
+<div class="container">
+  <div class="item rtl" style="align-self: start;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: center;" data-expected-width="20" data-offset-x="10"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: end;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: baseline;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: last baseline;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: self-start;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: self-end;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="align-self: stretch;" data-expected-width="40" data-offset-x="0"></div>
+</div>
+
diff --git a/testing/web-platform/tests/css/css-align/abspos/justify-self-htb-ltr-htb.html b/testing/web-platform/tests/css/css-align/abspos/justify-self-htb-ltr-htb.html
new file mode 100644
index 0000000000..cfef344e04
--- /dev/null
+++ b/testing/web-platform/tests/css/css-align/abspos/justify-self-htb-ltr-htb.html
@@ -0,0 +1,126 @@
+<!DOCTYPE html>
+<link rel="help" href="https://drafts.csswg.org/css-align-3/#justify-abspos">
+<style>
+body {
+  margin: 0;
+}
+
+.container {
+  writing-mode: horizontal-tb;
+  direction: ltr;
+  display: inline-block;
+  position: relative;
+  margin: 20px;
+  border: solid 4px;
+  width: 40px;
+  height: 40px;
+}
+
+.item {
+  writing-mode: horizontal-tb;
+  direction: ltr;
+  position: absolute;
+  background: green;
+  inset: 0;
+}
+
+.item::before {
+  width: 20px;
+  height: 20px;
+  content: '';
+  display: block;
+}
+
+.rtl {
+  direction: rtl;
+}
+</style>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/check-layout-th.js"></script>
+
+<body onload="checkLayout('.item')">
+
+<div class="container">
+  <div class="item" style="justify-self: start;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: center;" data-expected-width="20" data-offset-x="10"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: end;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: baseline;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: last baseline;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: self-start;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: self-end;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: left;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: right;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: stretch;" data-expected-width="40" data-offset-x="0"></div>
+</div>
+
+<!-- RTL -->
+<br>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: start;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: center;" data-expected-width="20" data-offset-x="10"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: end;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: baseline;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: last baseline;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: self-start;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: self-end;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: left;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: right;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: stretch;" data-expected-width="40" data-offset-x="0"></div>
+</div>
+
diff --git a/testing/web-platform/tests/css/css-align/abspos/justify-self-htb-ltr-vlr.html b/testing/web-platform/tests/css/css-align/abspos/justify-self-htb-ltr-vlr.html
new file mode 100644
index 0000000000..55680f4b2c
--- /dev/null
+++ b/testing/web-platform/tests/css/css-align/abspos/justify-self-htb-ltr-vlr.html
@@ -0,0 +1,126 @@
+<!DOCTYPE html>
+<link rel="help" href="https://drafts.csswg.org/css-align-3/#justify-abspos">
+<style>
+body {
+  margin: 0;
+}
+
+.container {
+  writing-mode: horizontal-tb;
+  direction: ltr;
+  display: inline-block;
+  position: relative;
+  margin: 20px;
+  border: solid 4px;
+  width: 40px;
+  height: 40px;
+}
+
+.item {
+  writing-mode: vertical-lr;
+  direction: ltr;
+  position: absolute;
+  background: green;
+  inset: 0;
+}
+
+.item::before {
+  width: 20px;
+  height: 20px;
+  content: '';
+  display: block;
+}
+
+.rtl {
+  direction: rtl;
+}
+</style>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/check-layout-th.js"></script>
+
+<body onload="checkLayout('.item')">
+
+<div class="container">
+  <div class="item" style="justify-self: start;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: center;" data-expected-width="20" data-offset-x="10"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: end;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: baseline;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: last baseline;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: self-start;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: self-end;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: left;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: right;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: stretch;" data-expected-width="40" data-offset-x="0"></div>
+</div>
+
+<!-- RTL -->
+<br>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: start;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: center;" data-expected-width="20" data-offset-x="10"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: end;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: baseline;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: last baseline;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: self-start;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: self-end;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: left;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: right;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: stretch;" data-expected-width="40" data-offset-x="0"></div>
+</div>
+
diff --git a/testing/web-platform/tests/css/css-align/abspos/justify-self-htb-ltr-vrl.html b/testing/web-platform/tests/css/css-align/abspos/justify-self-htb-ltr-vrl.html
new file mode 100644
index 0000000000..57ee3af640
--- /dev/null
+++ b/testing/web-platform/tests/css/css-align/abspos/justify-self-htb-ltr-vrl.html
@@ -0,0 +1,126 @@
+<!DOCTYPE html>
+<link rel="help" href="https://drafts.csswg.org/css-align-3/#justify-abspos">
+<style>
+body {
+  margin: 0;
+}
+
+.container {
+  writing-mode: horizontal-tb;
+  direction: ltr;
+  display: inline-block;
+  position: relative;
+  margin: 20px;
+  border: solid 4px;
+  width: 40px;
+  height: 40px;
+}
+
+.item {
+  writing-mode: vertical-rl;
+  direction: ltr;
+  position: absolute;
+  background: green;
+  inset: 0;
+}
+
+.item::before {
+  width: 20px;
+  height: 20px;
+  content: '';
+  display: block;
+}
+
+.rtl {
+  direction: rtl;
+}
+</style>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/check-layout-th.js"></script>
+
+<body onload="checkLayout('.item')">
+
+<div class="container">
+  <div class="item" style="justify-self: start;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: center;" data-expected-width="20" data-offset-x="10"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: end;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: baseline;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: last baseline;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: self-start;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: self-end;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: left;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: right;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: stretch;" data-expected-width="40" data-offset-x="0"></div>
+</div>
+
+<!-- RTL -->
+<br>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: start;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: center;" data-expected-width="20" data-offset-x="10"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: end;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: baseline;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: last baseline;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: self-start;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: self-end;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: left;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: right;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: stretch;" data-expected-width="40" data-offset-x="0"></div>
+</div>
+
diff --git a/testing/web-platform/tests/css/css-align/abspos/justify-self-htb-rtl-htb.html b/testing/web-platform/tests/css/css-align/abspos/justify-self-htb-rtl-htb.html
new file mode 100644
index 0000000000..95e54c2b99
--- /dev/null
+++ b/testing/web-platform/tests/css/css-align/abspos/justify-self-htb-rtl-htb.html
@@ -0,0 +1,126 @@
+<!DOCTYPE html>
+<link rel="help" href="https://drafts.csswg.org/css-align-3/#justify-abspos">
+<style>
+body {
+  margin: 0;
+}
+
+.container {
+  writing-mode: horizontal-tb;
+  direction: rtl;
+  display: inline-block;
+  position: relative;
+  margin: 20px;
+  border: solid 4px;
+  width: 40px;
+  height: 40px;
+}
+
+.item {
+  writing-mode: horizontal-tb;
+  direction: ltr;
+  position: absolute;
+  background: green;
+  inset: 0;
+}
+
+.item::before {
+  width: 20px;
+  height: 20px;
+  content: '';
+  display: block;
+}
+
+.rtl {
+  direction: rtl;
+}
+</style>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/check-layout-th.js"></script>
+
+<body onload="checkLayout('.item')">
+
+<div class="container">
+  <div class="item" style="justify-self: start;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: center;" data-expected-width="20" data-offset-x="10"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: end;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: baseline;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: last baseline;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: self-start;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: self-end;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: left;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: right;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: stretch;" data-expected-width="40" data-offset-x="0"></div>
+</div>
+
+<!-- RTL -->
+<br>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: start;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: center;" data-expected-width="20" data-offset-x="10"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: end;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: baseline;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: last baseline;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: self-start;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: self-end;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: left;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: right;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: stretch;" data-expected-width="40" data-offset-x="0"></div>
+</div>
+
diff --git a/testing/web-platform/tests/css/css-align/abspos/justify-self-htb-rtl-vlr.html b/testing/web-platform/tests/css/css-align/abspos/justify-self-htb-rtl-vlr.html
new file mode 100644
index 0000000000..e7224e76db
--- /dev/null
+++ b/testing/web-platform/tests/css/css-align/abspos/justify-self-htb-rtl-vlr.html
@@ -0,0 +1,126 @@
+<!DOCTYPE html>
+<link rel="help" href="https://drafts.csswg.org/css-align-3/#justify-abspos">
+<style>
+body {
+  margin: 0;
+}
+
+.container {
+  writing-mode: horizontal-tb;
+  direction: rtl;
+  display: inline-block;
+  position: relative;
+  margin: 20px;
+  border: solid 4px;
+  width: 40px;
+  height: 40px;
+}
+
+.item {
+  writing-mode: vertical-lr;
+  direction: ltr;
+  position: absolute;
+  background: green;
+  inset: 0;
+}
+
+.item::before {
+  width: 20px;
+  height: 20px;
+  content: '';
+  display: block;
+}
+
+.rtl {
+  direction: rtl;
+}
+</style>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/check-layout-th.js"></script>
+
+<body onload="checkLayout('.item')">
+
+<div class="container">
+  <div class="item" style="justify-self: start;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: center;" data-expected-width="20" data-offset-x="10"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: end;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: baseline;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: last baseline;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: self-start;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: self-end;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: left;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: right;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: stretch;" data-expected-width="40" data-offset-x="0"></div>
+</div>
+
+<!-- RTL -->
+<br>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: start;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: center;" data-expected-width="20" data-offset-x="10"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: end;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: baseline;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: last baseline;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: self-start;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: self-end;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: left;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: right;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: stretch;" data-expected-width="40" data-offset-x="0"></div>
+</div>
+
diff --git a/testing/web-platform/tests/css/css-align/abspos/justify-self-htb-rtl-vrl.html b/testing/web-platform/tests/css/css-align/abspos/justify-self-htb-rtl-vrl.html
new file mode 100644
index 0000000000..ba7e98a676
--- /dev/null
+++ b/testing/web-platform/tests/css/css-align/abspos/justify-self-htb-rtl-vrl.html
@@ -0,0 +1,126 @@
+<!DOCTYPE html>
+<link rel="help" href="https://drafts.csswg.org/css-align-3/#justify-abspos">
+<style>
+body {
+  margin: 0;
+}
+
+.container {
+  writing-mode: horizontal-tb;
+  direction: rtl;
+  display: inline-block;
+  position: relative;
+  margin: 20px;
+  border: solid 4px;
+  width: 40px;
+  height: 40px;
+}
+
+.item {
+  writing-mode: vertical-rl;
+  direction: ltr;
+  position: absolute;
+  background: green;
+  inset: 0;
+}
+
+.item::before {
+  width: 20px;
+  height: 20px;
+  content: '';
+  display: block;
+}
+
+.rtl {
+  direction: rtl;
+}
+</style>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/check-layout-th.js"></script>
+
+<body onload="checkLayout('.item')">
+
+<div class="container">
+  <div class="item" style="justify-self: start;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: center;" data-expected-width="20" data-offset-x="10"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: end;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: baseline;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: last baseline;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: self-start;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: self-end;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: left;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: right;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: stretch;" data-expected-width="40" data-offset-x="0"></div>
+</div>
+
+<!-- RTL -->
+<br>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: start;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: center;" data-expected-width="20" data-offset-x="10"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: end;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: baseline;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: last baseline;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: self-start;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: self-end;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: left;" data-expected-width="20" data-offset-x="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: right;" data-expected-width="20" data-offset-x="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: stretch;" data-expected-width="40" data-offset-x="0"></div>
+</div>
+
diff --git a/testing/web-platform/tests/css/css-align/abspos/justify-self-vlr-ltr-htb.html b/testing/web-platform/tests/css/css-align/abspos/justify-self-vlr-ltr-htb.html
new file mode 100644
index 0000000000..d47c504679
--- /dev/null
+++ b/testing/web-platform/tests/css/css-align/abspos/justify-self-vlr-ltr-htb.html
@@ -0,0 +1,126 @@
+<!DOCTYPE html>
+<link rel="help" href="https://drafts.csswg.org/css-align-3/#justify-abspos">
+<style>
+body {
+  margin: 0;
+}
+
+.container {
+  writing-mode: vertical-lr;
+  direction: ltr;
+  display: inline-block;
+  position: relative;
+  margin: 20px;
+  border: solid 4px;
+  width: 40px;
+  height: 40px;
+}
+
+.item {
+  writing-mode: horizontal-tb;
+  direction: ltr;
+  position: absolute;
+  background: green;
+  inset: 0;
+}
+
+.item::before {
+  width: 20px;
+  height: 20px;
+  content: '';
+  display: block;
+}
+
+.rtl {
+  direction: rtl;
+}
+</style>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/check-layout-th.js"></script>
+
+<body onload="checkLayout('.item')">
+
+<div class="container">
+  <div class="item" style="justify-self: start;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: center;" data-expected-height="20" data-offset-y="10"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: end;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: baseline;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: last baseline;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: self-start;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: self-end;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: left;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: right;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: stretch;" data-expected-height="40" data-offset-y="0"></div>
+</div>
+
+<!-- RTL -->
+<br>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: start;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: center;" data-expected-height="20" data-offset-y="10"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: end;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: baseline;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: last baseline;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: self-start;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: self-end;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: left;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: right;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: stretch;" data-expected-height="40" data-offset-y="0"></div>
+</div>
+
diff --git a/testing/web-platform/tests/css/css-align/abspos/justify-self-vlr-ltr-vlr.html b/testing/web-platform/tests/css/css-align/abspos/justify-self-vlr-ltr-vlr.html
new file mode 100644
index 0000000000..71e3687f6f
--- /dev/null
+++ b/testing/web-platform/tests/css/css-align/abspos/justify-self-vlr-ltr-vlr.html
@@ -0,0 +1,126 @@
+<!DOCTYPE html>
+<link rel="help" href="https://drafts.csswg.org/css-align-3/#justify-abspos">
+<style>
+body {
+  margin: 0;
+}
+
+.container {
+  writing-mode: vertical-lr;
+  direction: ltr;
+  display: inline-block;
+  position: relative;
+  margin: 20px;
+  border: solid 4px;
+  width: 40px;
+  height: 40px;
+}
+
+.item {
+  writing-mode: vertical-lr;
+  direction: ltr;
+  position: absolute;
+  background: green;
+  inset: 0;
+}
+
+.item::before {
+  width: 20px;
+  height: 20px;
+  content: '';
+  display: block;
+}
+
+.rtl {
+  direction: rtl;
+}
+</style>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/check-layout-th.js"></script>
+
+<body onload="checkLayout('.item')">
+
+<div class="container">
+  <div class="item" style="justify-self: start;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: center;" data-expected-height="20" data-offset-y="10"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: end;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: baseline;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: last baseline;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: self-start;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: self-end;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: left;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: right;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: stretch;" data-expected-height="40" data-offset-y="0"></div>
+</div>
+
+<!-- RTL -->
+<br>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: start;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: center;" data-expected-height="20" data-offset-y="10"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: end;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: baseline;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: last baseline;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: self-start;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: self-end;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: left;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: right;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: stretch;" data-expected-height="40" data-offset-y="0"></div>
+</div>
+
diff --git a/testing/web-platform/tests/css/css-align/abspos/justify-self-vlr-ltr-vrl.html b/testing/web-platform/tests/css/css-align/abspos/justify-self-vlr-ltr-vrl.html
new file mode 100644
index 0000000000..ae90d4da0d
--- /dev/null
+++ b/testing/web-platform/tests/css/css-align/abspos/justify-self-vlr-ltr-vrl.html
@@ -0,0 +1,126 @@
+<!DOCTYPE html>
+<link rel="help" href="https://drafts.csswg.org/css-align-3/#justify-abspos">
+<style>
+body {
+  margin: 0;
+}
+
+.container {
+  writing-mode: vertical-lr;
+  direction: ltr;
+  display: inline-block;
+  position: relative;
+  margin: 20px;
+  border: solid 4px;
+  width: 40px;
+  height: 40px;
+}
+
+.item {
+  writing-mode: vertical-rl;
+  direction: ltr;
+  position: absolute;
+  background: green;
+  inset: 0;
+}
+
+.item::before {
+  width: 20px;
+  height: 20px;
+  content: '';
+  display: block;
+}
+
+.rtl {
+  direction: rtl;
+}
+</style>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/check-layout-th.js"></script>
+
+<body onload="checkLayout('.item')">
+
+<div class="container">
+  <div class="item" style="justify-self: start;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: center;" data-expected-height="20" data-offset-y="10"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: end;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: baseline;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: last baseline;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: self-start;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: self-end;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: left;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: right;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: stretch;" data-expected-height="40" data-offset-y="0"></div>
+</div>
+
+<!-- RTL -->
+<br>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: start;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: center;" data-expected-height="20" data-offset-y="10"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: end;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: baseline;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: last baseline;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: self-start;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: self-end;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: left;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: right;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: stretch;" data-expected-height="40" data-offset-y="0"></div>
+</div>
+
diff --git a/testing/web-platform/tests/css/css-align/abspos/justify-self-vlr-rtl-htb.html b/testing/web-platform/tests/css/css-align/abspos/justify-self-vlr-rtl-htb.html
new file mode 100644
index 0000000000..1a192b5692
--- /dev/null
+++ b/testing/web-platform/tests/css/css-align/abspos/justify-self-vlr-rtl-htb.html
@@ -0,0 +1,126 @@
+<!DOCTYPE html>
+<link rel="help" href="https://drafts.csswg.org/css-align-3/#justify-abspos">
+<style>
+body {
+  margin: 0;
+}
+
+.container {
+  writing-mode: vertical-lr;
+  direction: rtl;
+  display: inline-block;
+  position: relative;
+  margin: 20px;
+  border: solid 4px;
+  width: 40px;
+  height: 40px;
+}
+
+.item {
+  writing-mode: horizontal-tb;
+  direction: ltr;
+  position: absolute;
+  background: green;
+  inset: 0;
+}
+
+.item::before {
+  width: 20px;
+  height: 20px;
+  content: '';
+  display: block;
+}
+
+.rtl {
+  direction: rtl;
+}
+</style>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/check-layout-th.js"></script>
+
+<body onload="checkLayout('.item')">
+
+<div class="container">
+  <div class="item" style="justify-self: start;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: center;" data-expected-height="20" data-offset-y="10"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: end;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: baseline;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: last baseline;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: self-start;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: self-end;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: left;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: right;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: stretch;" data-expected-height="40" data-offset-y="0"></div>
+</div>
+
+<!-- RTL -->
+<br>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: start;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: center;" data-expected-height="20" data-offset-y="10"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: end;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: baseline;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: last baseline;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: self-start;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: self-end;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: left;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: right;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: stretch;" data-expected-height="40" data-offset-y="0"></div>
+</div>
+
diff --git a/testing/web-platform/tests/css/css-align/abspos/justify-self-vlr-rtl-vlr.html b/testing/web-platform/tests/css/css-align/abspos/justify-self-vlr-rtl-vlr.html
new file mode 100644
index 0000000000..cb9986db10
--- /dev/null
+++ b/testing/web-platform/tests/css/css-align/abspos/justify-self-vlr-rtl-vlr.html
@@ -0,0 +1,126 @@
+<!DOCTYPE html>
+<link rel="help" href="https://drafts.csswg.org/css-align-3/#justify-abspos">
+<style>
+body {
+  margin: 0;
+}
+
+.container {
+  writing-mode: vertical-lr;
+  direction: rtl;
+  display: inline-block;
+  position: relative;
+  margin: 20px;
+  border: solid 4px;
+  width: 40px;
+  height: 40px;
+}
+
+.item {
+  writing-mode: vertical-lr;
+  direction: ltr;
+  position: absolute;
+  background: green;
+  inset: 0;
+}
+
+.item::before {
+  width: 20px;
+  height: 20px;
+  content: '';
+  display: block;
+}
+
+.rtl {
+  direction: rtl;
+}
+</style>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/check-layout-th.js"></script>
+
+<body onload="checkLayout('.item')">
+
+<div class="container">
+  <div class="item" style="justify-self: start;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: center;" data-expected-height="20" data-offset-y="10"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: end;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: baseline;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: last baseline;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: self-start;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: self-end;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: left;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: right;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: stretch;" data-expected-height="40" data-offset-y="0"></div>
+</div>
+
+<!-- RTL -->
+<br>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: start;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: center;" data-expected-height="20" data-offset-y="10"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: end;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: baseline;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: last baseline;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: self-start;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: self-end;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: left;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: right;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: stretch;" data-expected-height="40" data-offset-y="0"></div>
+</div>
+
diff --git a/testing/web-platform/tests/css/css-align/abspos/justify-self-vlr-rtl-vrl.html b/testing/web-platform/tests/css/css-align/abspos/justify-self-vlr-rtl-vrl.html
new file mode 100644
index 0000000000..fb717a051f
--- /dev/null
+++ b/testing/web-platform/tests/css/css-align/abspos/justify-self-vlr-rtl-vrl.html
@@ -0,0 +1,126 @@
+<!DOCTYPE html>
+<link rel="help" href="https://drafts.csswg.org/css-align-3/#justify-abspos">
+<style>
+body {
+  margin: 0;
+}
+
+.container {
+  writing-mode: vertical-lr;
+  direction: rtl;
+  display: inline-block;
+  position: relative;
+  margin: 20px;
+  border: solid 4px;
+  width: 40px;
+  height: 40px;
+}
+
+.item {
+  writing-mode: vertical-rl;
+  direction: ltr;
+  position: absolute;
+  background: green;
+  inset: 0;
+}
+
+.item::before {
+  width: 20px;
+  height: 20px;
+  content: '';
+  display: block;
+}
+
+.rtl {
+  direction: rtl;
+}
+</style>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/check-layout-th.js"></script>
+
+<body onload="checkLayout('.item')">
+
+<div class="container">
+  <div class="item" style="justify-self: start;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: center;" data-expected-height="20" data-offset-y="10"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: end;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: baseline;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: last baseline;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: self-start;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: self-end;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: left;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: right;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: stretch;" data-expected-height="40" data-offset-y="0"></div>
+</div>
+
+<!-- RTL -->
+<br>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: start;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: center;" data-expected-height="20" data-offset-y="10"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: end;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: baseline;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: last baseline;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: self-start;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: self-end;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: left;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: right;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: stretch;" data-expected-height="40" data-offset-y="0"></div>
+</div>
+
diff --git a/testing/web-platform/tests/css/css-align/abspos/justify-self-vrl-ltr-htb.html b/testing/web-platform/tests/css/css-align/abspos/justify-self-vrl-ltr-htb.html
new file mode 100644
index 0000000000..e2cbff322b
--- /dev/null
+++ b/testing/web-platform/tests/css/css-align/abspos/justify-self-vrl-ltr-htb.html
@@ -0,0 +1,126 @@
+<!DOCTYPE html>
+<link rel="help" href="https://drafts.csswg.org/css-align-3/#justify-abspos">
+<style>
+body {
+  margin: 0;
+}
+
+.container {
+  writing-mode: vertical-rl;
+  direction: ltr;
+  display: inline-block;
+  position: relative;
+  margin: 20px;
+  border: solid 4px;
+  width: 40px;
+  height: 40px;
+}
+
+.item {
+  writing-mode: horizontal-tb;
+  direction: ltr;
+  position: absolute;
+  background: green;
+  inset: 0;
+}
+
+.item::before {
+  width: 20px;
+  height: 20px;
+  content: '';
+  display: block;
+}
+
+.rtl {
+  direction: rtl;
+}
+</style>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/check-layout-th.js"></script>
+
+<body onload="checkLayout('.item')">
+
+<div class="container">
+  <div class="item" style="justify-self: start;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: center;" data-expected-height="20" data-offset-y="10"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: end;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: baseline;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: last baseline;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: self-start;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: self-end;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: left;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: right;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: stretch;" data-expected-height="40" data-offset-y="0"></div>
+</div>
+
+<!-- RTL -->
+<br>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: start;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: center;" data-expected-height="20" data-offset-y="10"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: end;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: baseline;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: last baseline;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: self-start;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: self-end;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: left;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: right;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: stretch;" data-expected-height="40" data-offset-y="0"></div>
+</div>
+
diff --git a/testing/web-platform/tests/css/css-align/abspos/justify-self-vrl-ltr-vlr.html b/testing/web-platform/tests/css/css-align/abspos/justify-self-vrl-ltr-vlr.html
new file mode 100644
index 0000000000..5aa2f48288
--- /dev/null
+++ b/testing/web-platform/tests/css/css-align/abspos/justify-self-vrl-ltr-vlr.html
@@ -0,0 +1,126 @@
+<!DOCTYPE html>
+<link rel="help" href="https://drafts.csswg.org/css-align-3/#justify-abspos">
+<style>
+body {
+  margin: 0;
+}
+
+.container {
+  writing-mode: vertical-rl;
+  direction: ltr;
+  display: inline-block;
+  position: relative;
+  margin: 20px;
+  border: solid 4px;
+  width: 40px;
+  height: 40px;
+}
+
+.item {
+  writing-mode: vertical-lr;
+  direction: ltr;
+  position: absolute;
+  background: green;
+  inset: 0;
+}
+
+.item::before {
+  width: 20px;
+  height: 20px;
+  content: '';
+  display: block;
+}
+
+.rtl {
+  direction: rtl;
+}
+</style>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/check-layout-th.js"></script>
+
+<body onload="checkLayout('.item')">
+
+<div class="container">
+  <div class="item" style="justify-self: start;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: center;" data-expected-height="20" data-offset-y="10"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: end;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: baseline;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: last baseline;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: self-start;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: self-end;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: left;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: right;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: stretch;" data-expected-height="40" data-offset-y="0"></div>
+</div>
+
+<!-- RTL -->
+<br>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: start;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: center;" data-expected-height="20" data-offset-y="10"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: end;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: baseline;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: last baseline;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: self-start;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: self-end;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: left;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: right;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: stretch;" data-expected-height="40" data-offset-y="0"></div>
+</div>
+
diff --git a/testing/web-platform/tests/css/css-align/abspos/justify-self-vrl-ltr-vrl.html b/testing/web-platform/tests/css/css-align/abspos/justify-self-vrl-ltr-vrl.html
new file mode 100644
index 0000000000..cf2db8d369
--- /dev/null
+++ b/testing/web-platform/tests/css/css-align/abspos/justify-self-vrl-ltr-vrl.html
@@ -0,0 +1,126 @@
+<!DOCTYPE html>
+<link rel="help" href="https://drafts.csswg.org/css-align-3/#justify-abspos">
+<style>
+body {
+  margin: 0;
+}
+
+.container {
+  writing-mode: vertical-rl;
+  direction: ltr;
+  display: inline-block;
+  position: relative;
+  margin: 20px;
+  border: solid 4px;
+  width: 40px;
+  height: 40px;
+}
+
+.item {
+  writing-mode: vertical-rl;
+  direction: ltr;
+  position: absolute;
+  background: green;
+  inset: 0;
+}
+
+.item::before {
+  width: 20px;
+  height: 20px;
+  content: '';
+  display: block;
+}
+
+.rtl {
+  direction: rtl;
+}
+</style>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/check-layout-th.js"></script>
+
+<body onload="checkLayout('.item')">
+
+<div class="container">
+  <div class="item" style="justify-self: start;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: center;" data-expected-height="20" data-offset-y="10"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: end;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: baseline;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: last baseline;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: self-start;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: self-end;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: left;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: right;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: stretch;" data-expected-height="40" data-offset-y="0"></div>
+</div>
+
+<!-- RTL -->
+<br>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: start;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: center;" data-expected-height="20" data-offset-y="10"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: end;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: baseline;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: last baseline;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: self-start;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: self-end;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: left;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: right;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: stretch;" data-expected-height="40" data-offset-y="0"></div>
+</div>
+
diff --git a/testing/web-platform/tests/css/css-align/abspos/justify-self-vrl-rtl-htb.html b/testing/web-platform/tests/css/css-align/abspos/justify-self-vrl-rtl-htb.html
new file mode 100644
index 0000000000..317e53e92e
--- /dev/null
+++ b/testing/web-platform/tests/css/css-align/abspos/justify-self-vrl-rtl-htb.html
@@ -0,0 +1,126 @@
+<!DOCTYPE html>
+<link rel="help" href="https://drafts.csswg.org/css-align-3/#justify-abspos">
+<style>
+body {
+  margin: 0;
+}
+
+.container {
+  writing-mode: vertical-rl;
+  direction: rtl;
+  display: inline-block;
+  position: relative;
+  margin: 20px;
+  border: solid 4px;
+  width: 40px;
+  height: 40px;
+}
+
+.item {
+  writing-mode: horizontal-tb;
+  direction: ltr;
+  position: absolute;
+  background: green;
+  inset: 0;
+}
+
+.item::before {
+  width: 20px;
+  height: 20px;
+  content: '';
+  display: block;
+}
+
+.rtl {
+  direction: rtl;
+}
+</style>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/check-layout-th.js"></script>
+
+<body onload="checkLayout('.item')">
+
+<div class="container">
+  <div class="item" style="justify-self: start;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: center;" data-expected-height="20" data-offset-y="10"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: end;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: baseline;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: last baseline;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: self-start;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: self-end;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: left;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: right;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: stretch;" data-expected-height="40" data-offset-y="0"></div>
+</div>
+
+<!-- RTL -->
+<br>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: start;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: center;" data-expected-height="20" data-offset-y="10"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: end;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: baseline;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: last baseline;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: self-start;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: self-end;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: left;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: right;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: stretch;" data-expected-height="40" data-offset-y="0"></div>
+</div>
+
diff --git a/testing/web-platform/tests/css/css-align/abspos/justify-self-vrl-rtl-vlr.html b/testing/web-platform/tests/css/css-align/abspos/justify-self-vrl-rtl-vlr.html
new file mode 100644
index 0000000000..2d144d16aa
--- /dev/null
+++ b/testing/web-platform/tests/css/css-align/abspos/justify-self-vrl-rtl-vlr.html
@@ -0,0 +1,126 @@
+<!DOCTYPE html>
+<link rel="help" href="https://drafts.csswg.org/css-align-3/#justify-abspos">
+<style>
+body {
+  margin: 0;
+}
+
+.container {
+  writing-mode: vertical-rl;
+  direction: rtl;
+  display: inline-block;
+  position: relative;
+  margin: 20px;
+  border: solid 4px;
+  width: 40px;
+  height: 40px;
+}
+
+.item {
+  writing-mode: vertical-lr;
+  direction: ltr;
+  position: absolute;
+  background: green;
+  inset: 0;
+}
+
+.item::before {
+  width: 20px;
+  height: 20px;
+  content: '';
+  display: block;
+}
+
+.rtl {
+  direction: rtl;
+}
+</style>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/check-layout-th.js"></script>
+
+<body onload="checkLayout('.item')">
+
+<div class="container">
+  <div class="item" style="justify-self: start;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: center;" data-expected-height="20" data-offset-y="10"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: end;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: baseline;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: last baseline;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: self-start;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: self-end;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: left;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: right;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: stretch;" data-expected-height="40" data-offset-y="0"></div>
+</div>
+
+<!-- RTL -->
+<br>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: start;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: center;" data-expected-height="20" data-offset-y="10"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: end;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: baseline;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: last baseline;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: self-start;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: self-end;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: left;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: right;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: stretch;" data-expected-height="40" data-offset-y="0"></div>
+</div>
+
diff --git a/testing/web-platform/tests/css/css-align/abspos/justify-self-vrl-rtl-vrl.html b/testing/web-platform/tests/css/css-align/abspos/justify-self-vrl-rtl-vrl.html
new file mode 100644
index 0000000000..026c6e9681
--- /dev/null
+++ b/testing/web-platform/tests/css/css-align/abspos/justify-self-vrl-rtl-vrl.html
@@ -0,0 +1,126 @@
+<!DOCTYPE html>
+<link rel="help" href="https://drafts.csswg.org/css-align-3/#justify-abspos">
+<style>
+body {
+  margin: 0;
+}
+
+.container {
+  writing-mode: vertical-rl;
+  direction: rtl;
+  display: inline-block;
+  position: relative;
+  margin: 20px;
+  border: solid 4px;
+  width: 40px;
+  height: 40px;
+}
+
+.item {
+  writing-mode: vertical-rl;
+  direction: ltr;
+  position: absolute;
+  background: green;
+  inset: 0;
+}
+
+.item::before {
+  width: 20px;
+  height: 20px;
+  content: '';
+  display: block;
+}
+
+.rtl {
+  direction: rtl;
+}
+</style>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/check-layout-th.js"></script>
+
+<body onload="checkLayout('.item')">
+
+<div class="container">
+  <div class="item" style="justify-self: start;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: center;" data-expected-height="20" data-offset-y="10"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: end;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: baseline;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: last baseline;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: self-start;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: self-end;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: left;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: right;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: stretch;" data-expected-height="40" data-offset-y="0"></div>
+</div>
+
+<!-- RTL -->
+<br>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: start;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: center;" data-expected-height="20" data-offset-y="10"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: end;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: baseline;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: last baseline;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: self-start;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: self-end;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: left;" data-expected-height="20" data-offset-y="0"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: right;" data-expected-height="20" data-offset-y="20"></div>
+</div>
+
+<div class="container">
+  <div class="item rtl" style="justify-self: stretch;" data-expected-height="40" data-offset-y="0"></div>
+</div>
+
diff --git a/testing/web-platform/tests/css/css-align/abspos/safe-align-self-htb.html b/testing/web-platform/tests/css/css-align/abspos/safe-align-self-htb.html
new file mode 100644
index 0000000000..9e259c1e63
--- /dev/null
+++ b/testing/web-platform/tests/css/css-align/abspos/safe-align-self-htb.html
@@ -0,0 +1,149 @@
+<!DOCTYPE html>
+<link rel="help" href="https://drafts.csswg.org/css-align-3/#align-abspos">
+<style>
+body {
+  margin: 0;
+}
+
+.container {
+  writing-mode: horizontal-tb;
+  direction: ltr;
+  display: inline-block;
+  position: relative;
+  margin: 20px;
+  border: solid 4px;
+  width: 40px;
+  height: 40px;
+}
+
+.item {
+  position: absolute;
+  background: green;
+  inset: 5px;
+  margin: 10px;
+  width: 30px;
+  height: 30px;
+}
+
+.safe {
+  align-self: safe end;
+}
+.unsafe {
+  align-self: unsafe end;
+}
+
+.rtl {
+  direction: rtl;
+}
+</style>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/check-layout-th.js"></script>
+
+<body onload="checkLayout('.item')">
+
+<div class="container">
+  <div class="item safe" style="writing-mode: horizontal-tb; direction: ltr;" data-offset-y="15"></div>
+</div>
+
+<div class="container">
+  <div class="item safe" style="writing-mode: horizontal-tb; direction: rtl;" data-offset-y="15"></div>
+</div>
+
+<div class="container">
+  <div class="item safe" style="writing-mode: veritcal-rl; direction: ltr;" data-offset-y="15"></div>
+</div>
+
+<div class="container">
+  <div class="item safe" style="writing-mode: vertical-rl; direction: rtl;" data-offset-y="15"></div>
+</div>
+
+<div class="container">
+  <div class="item safe" style="writing-mode: vertical-lr; direction: ltr;" data-offset-y="15"></div>
+</div>
+
+<div class="container">
+  <div class="item safe" style="writing-mode: vertical-lr; direction: rtl;" data-offset-y="15"></div>
+</div>
+
+<!-- UNSAFE -->
+<br>
+
+<div class="container">
+  <div class="item unsafe" style="writing-mode: horizontal-tb; direction: ltr;" data-offset-y="-5"></div>
+</div>
+
+<div class="container">
+  <div class="item unsafe" style="writing-mode: horizontal-tb; direction: rtl;" data-offset-y="-5"></div>
+</div>
+
+<div class="container">
+  <div class="item unsafe" style="writing-mode: veritcal-rl; direction: ltr;" data-offset-y="-5"></div>
+</div>
+
+<div class="container">
+  <div class="item unsafe" style="writing-mode: vertical-rl; direction: rtl;" data-offset-y="-5"></div>
+</div>
+
+<div class="container">
+  <div class="item unsafe" style="writing-mode: vertical-lr; direction: ltr;" data-offset-y="-5"></div>
+</div>
+
+<div class="container">
+  <div class="item unsafe" style="writing-mode: vertical-lr; direction: rtl;" data-offset-y="-5"></div>
+</div>
+
+<!-- RTL -->
+<br>
+
+<div class="container rtl">
+  <div class="item safe" style="writing-mode: horizontal-tb; direction: ltr;" data-offset-y="15"></div>
+</div>
+
+<div class="container rtl">
+  <div class="item safe" style="writing-mode: horizontal-tb; direction: rtl;" data-offset-y="15"></div>
+</div>
+
+<div class="container rtl">
+  <div class="item safe" style="writing-mode: veritcal-rl; direction: ltr;" data-offset-y="15"></div>
+</div>
+
+<div class="container rtl">
+  <div class="item safe" style="writing-mode: vertical-rl; direction: rtl;" data-offset-y="15"></div>
+</div>
+
+<div class="container rtl">
+  <div class="item safe" style="writing-mode: vertical-lr; direction: ltr;" data-offset-y="15"></div>
+</div>
+
+<div class="container rtl">
+  <div class="item safe" style="writing-mode: vertical-lr; direction: rtl;" data-offset-y="15"></div>
+</div>
+
+<!-- UNSAFE RTL -->
+<br>
+
+<div class="container rtl">
+  <div class="item unsafe" style="writing-mode: horizontal-tb; direction: ltr;" data-offset-y="-5"></div>
+</div>
+
+<div class="container rtl">
+  <div class="item unsafe" style="writing-mode: horizontal-tb; direction: rtl;" data-offset-y="-5"></div>
+</div>
+
+<div class="container rtl">
+  <div class="item unsafe" style="writing-mode: veritcal-rl; direction: ltr;" data-offset-y="-5"></div>
+</div>
+
+<div class="container rtl">
+  <div class="item unsafe" style="writing-mode: vertical-rl; direction: rtl;" data-offset-y="-5"></div>
+</div>
+
+<div class="container rtl">
+  <div class="item unsafe" style="writing-mode: vertical-lr; direction: ltr;" data-offset-y="-5"></div>
+</div>
+
+<div class="container rtl">
+  <div class="item unsafe" style="writing-mode: vertical-lr; direction: rtl;" data-offset-y="-5"></div>
+</div>
+
diff --git a/testing/web-platform/tests/css/css-align/abspos/safe-align-self-vlr.html b/testing/web-platform/tests/css/css-align/abspos/safe-align-self-vlr.html
new file mode 100644
index 0000000000..d47b1836d5
--- /dev/null
+++ b/testing/web-platform/tests/css/css-align/abspos/safe-align-self-vlr.html
@@ -0,0 +1,149 @@
+<!DOCTYPE html>
+<link rel="help" href="https://drafts.csswg.org/css-align-3/#align-abspos">
+<style>
+body {
+  margin: 0;
+}
+
+.container {
+  writing-mode: vertical-lr;
+  direction: ltr;
+  display: inline-block;
+  position: relative;
+  margin: 20px;
+  border: solid 4px;
+  width: 40px;
+  height: 40px;
+}
+
+.item {
+  position: absolute;
+  background: green;
+  inset: 5px;
+  margin: 10px;
+  width: 30px;
+  height: 30px;
+}
+
+.safe {
+  align-self: safe end;
+}
+.unsafe {
+  align-self: unsafe end;
+}
+
+.rtl {
+  direction: rtl;
+}
+</style>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/check-layout-th.js"></script>
+
+<body onload="checkLayout('.item')">
+
+<div class="container">
+  <div class="item safe" style="writing-mode: horizontal-tb; direction: ltr;" data-offset-x="15"></div>
+</div>
+
+<div class="container">
+  <div class="item safe" style="writing-mode: horizontal-tb; direction: rtl;" data-offset-x="15"></div>
+</div>
+
+<div class="container">
+  <div class="item safe" style="writing-mode: veritcal-rl; direction: ltr;" data-offset-x="15"></div>
+</div>
+
+<div class="container">
+  <div class="item safe" style="writing-mode: vertical-rl; direction: rtl;" data-offset-x="15"></div>
+</div>
+
+<div class="container">
+  <div class="item safe" style="writing-mode: vertical-lr; direction: ltr;" data-offset-x="15"></div>
+</div>
+
+<div class="container">
+  <div class="item safe" style="writing-mode: vertical-lr; direction: rtl;" data-offset-x="15"></div>
+</div>
+
+<!-- UNSAFE -->
+<br>
+
+<div class="container">
+  <div class="item unsafe" style="writing-mode: horizontal-tb; direction: ltr;" data-offset-x="-5"></div>
+</div>
+
+<div class="container">
+  <div class="item unsafe" style="writing-mode: horizontal-tb; direction: rtl;" data-offset-x="-5"></div>
+</div>
+
+<div class="container">
+  <div class="item unsafe" style="writing-mode: veritcal-rl; direction: ltr;" data-offset-x="-5"></div>
+</div>
+
+<div class="container">
+  <div class="item unsafe" style="writing-mode: vertical-rl; direction: rtl;" data-offset-x="-5"></div>
+</div>
+
+<div class="container">
+  <div class="item unsafe" style="writing-mode: vertical-lr; direction: ltr;" data-offset-x="-5"></div>
+</div>
+
+<div class="container">
+  <div class="item unsafe" style="writing-mode: vertical-lr; direction: rtl;" data-offset-x="-5"></div>
+</div>
+
+<!-- RTL -->
+<br>
+
+<div class="container rtl">
+  <div class="item safe" style="writing-mode: horizontal-tb; direction: ltr;" data-offset-x="15"></div>
+</div>
+
+<div class="container rtl">
+  <div class="item safe" style="writing-mode: horizontal-tb; direction: rtl;" data-offset-x="15"></div>
+</div>
+
+<div class="container rtl">
+  <div class="item safe" style="writing-mode: veritcal-rl; direction: ltr;" data-offset-x="15"></div>
+</div>
+
+<div class="container rtl">
+  <div class="item safe" style="writing-mode: vertical-rl; direction: rtl;" data-offset-x="15"></div>
+</div>
+
+<div class="container rtl">
+  <div class="item safe" style="writing-mode: vertical-lr; direction: ltr;" data-offset-x="15"></div>
+</div>
+
+<div class="container rtl">
+  <div class="item safe" style="writing-mode: vertical-lr; direction: rtl;" data-offset-x="15"></div>
+</div>
+
+<!-- UNSAFE RTL -->
+<br>
+
+<div class="container rtl">
+  <div class="item unsafe" style="writing-mode: horizontal-tb; direction: ltr;" data-offset-x="-5"></div>
+</div>
+
+<div class="container rtl">
+  <div class="item unsafe" style="writing-mode: horizontal-tb; direction: rtl;" data-offset-x="-5"></div>
+</div>
+
+<div class="container rtl">
+  <div class="item unsafe" style="writing-mode: veritcal-rl; direction: ltr;" data-offset-x="-5"></div>
+</div>
+
+<div class="container rtl">
+  <div class="item unsafe" style="writing-mode: vertical-rl; direction: rtl;" data-offset-x="-5"></div>
+</div>
+
+<div class="container rtl">
+  <div class="item unsafe" style="writing-mode: vertical-lr; direction: ltr;" data-offset-x="-5"></div>
+</div>
+
+<div class="container rtl">
+  <div class="item unsafe" style="writing-mode: vertical-lr; direction: rtl;" data-offset-x="-5"></div>
+</div>
+
diff --git a/testing/web-platform/tests/css/css-align/abspos/safe-align-self-vrl.html b/testing/web-platform/tests/css/css-align/abspos/safe-align-self-vrl.html
new file mode 100644
index 0000000000..3432762007
--- /dev/null
+++ b/testing/web-platform/tests/css/css-align/abspos/safe-align-self-vrl.html
@@ -0,0 +1,149 @@
+<!DOCTYPE html>
+<link rel="help" href="https://drafts.csswg.org/css-align-3/#align-abspos">
+<style>
+body {
+  margin: 0;
+}
+
+.container {
+  writing-mode: vertical-rl;
+  direction: ltr;
+  display: inline-block;
+  position: relative;
+  margin: 20px;
+  border: solid 4px;
+  width: 40px;
+  height: 40px;
+}
+
+.item {
+  position: absolute;
+  background: green;
+  inset: 5px;
+  margin: 10px;
+  width: 30px;
+  height: 30px;
+}
+
+.safe {
+  align-self: safe end;
+}
+.unsafe {
+  align-self: unsafe end;
+}
+
+.rtl {
+  direction: rtl;
+}
+</style>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/check-layout-th.js"></script>
+
+<body onload="checkLayout('.item')">
+
+<div class="container">
+  <div class="item safe" style="writing-mode: horizontal-tb; direction: ltr;" data-offset-x="-5"></div>
+</div>
+
+<div class="container">
+  <div class="item safe" style="writing-mode: horizontal-tb; direction: rtl;" data-offset-x="-5"></div>
+</div>
+
+<div class="container">
+  <div class="item safe" style="writing-mode: veritcal-rl; direction: ltr;" data-offset-x="-5"></div>
+</div>
+
+<div class="container">
+  <div class="item safe" style="writing-mode: vertical-rl; direction: rtl;" data-offset-x="-5"></div>
+</div>
+
+<div class="container">
+  <div class="item safe" style="writing-mode: vertical-lr; direction: ltr;" data-offset-x="-5"></div>
+</div>
+
+<div class="container">
+  <div class="item safe" style="writing-mode: vertical-lr; direction: rtl;" data-offset-x="-5"></div>
+</div>
+
+<!-- UNSAFE -->
+<br>
+
+<div class="container">
+  <div class="item unsafe" style="writing-mode: horizontal-tb; direction: ltr;" data-offset-x="15"></div>
+</div>
+
+<div class="container">
+  <div class="item unsafe" style="writing-mode: horizontal-tb; direction: rtl;" data-offset-x="15"></div>
+</div>
+
+<div class="container">
+  <div class="item unsafe" style="writing-mode: veritcal-rl; direction: ltr;" data-offset-x="15"></div>
+</div>
+
+<div class="container">
+  <div class="item unsafe" style="writing-mode: vertical-rl; direction: rtl;" data-offset-x="15"></div>
+</div>
+
+<div class="container">
+  <div class="item unsafe" style="writing-mode: vertical-lr; direction: ltr;" data-offset-x="15"></div>
+</div>
+
+<div class="container">
+  <div class="item unsafe" style="writing-mode: vertical-lr; direction: rtl;" data-offset-x="15"></div>
+</div>
+
+<!-- RTL -->
+<br>
+
+<div class="container rtl">
+  <div class="item safe" style="writing-mode: horizontal-tb; direction: ltr;" data-offset-x="-5"></div>
+</div>
+
+<div class="container rtl">
+  <div class="item safe" style="writing-mode: horizontal-tb; direction: rtl;" data-offset-x="-5"></div>
+</div>
+
+<div class="container rtl">
+  <div class="item safe" style="writing-mode: veritcal-rl; direction: ltr;" data-offset-x="-5"></div>
+</div>
+
+<div class="container rtl">
+  <div class="item safe" style="writing-mode: vertical-rl; direction: rtl;" data-offset-x="-5"></div>
+</div>
+
+<div class="container rtl">
+  <div class="item safe" style="writing-mode: vertical-lr; direction: ltr;" data-offset-x="-5"></div>
+</div>
+
+<div class="container rtl">
+  <div class="item safe" style="writing-mode: vertical-lr; direction: rtl;" data-offset-x="-5"></div>
+</div>
+
+<!-- UNSAFE RTL -->
+<br>
+
+<div class="container rtl">
+  <div class="item unsafe" style="writing-mode: horizontal-tb; direction: ltr;" data-offset-x="15"></div>
+</div>
+
+<div class="container rtl">
+  <div class="item unsafe" style="writing-mode: horizontal-tb; direction: rtl;" data-offset-x="15"></div>
+</div>
+
+<div class="container rtl">
+  <div class="item unsafe" style="writing-mode: veritcal-rl; direction: ltr;" data-offset-x="15"></div>
+</div>
+
+<div class="container rtl">
+  <div class="item unsafe" style="writing-mode: vertical-rl; direction: rtl;" data-offset-x="15"></div>
+</div>
+
+<div class="container rtl">
+  <div class="item unsafe" style="writing-mode: vertical-lr; direction: ltr;" data-offset-x="15"></div>
+</div>
+
+<div class="container rtl">
+  <div class="item unsafe" style="writing-mode: vertical-lr; direction: rtl;" data-offset-x="15"></div>
+</div>
+
diff --git a/testing/web-platform/tests/css/css-align/abspos/safe-justify-self-htb.html b/testing/web-platform/tests/css/css-align/abspos/safe-justify-self-htb.html
new file mode 100644
index 0000000000..0fa5cc34d5
--- /dev/null
+++ b/testing/web-platform/tests/css/css-align/abspos/safe-justify-self-htb.html
@@ -0,0 +1,149 @@
+<!DOCTYPE html>
+<link rel="help" href="https://drafts.csswg.org/css-align-3/#justify-abspos">
+<style>
+body {
+  margin: 0;
+}
+
+.container {
+  writing-mode: horizontal-tb;
+  direction: ltr;
+  display: inline-block;
+  position: relative;
+  margin: 20px;
+  border: solid 4px;
+  width: 40px;
+  height: 40px;
+}
+
+.item {
+  position: absolute;
+  background: green;
+  inset: 5px;
+  margin: 10px;
+  width: 30px;
+  height: 30px;
+}
+
+.safe {
+  justify-self: safe end;
+}
+.unsafe {
+  justify-self: unsafe end;
+}
+
+.rtl {
+  direction: rtl;
+}
+</style>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/check-layout-th.js"></script>
+
+<body onload="checkLayout('.item')">
+
+<div class="container">
+  <div class="item safe" style="writing-mode: horizontal-tb; direction: ltr;" data-offset-x="15"></div>
+</div>
+
+<div class="container">
+  <div class="item safe" style="writing-mode: horizontal-tb; direction: rtl;" data-offset-x="15"></div>
+</div>
+
+<div class="container">
+  <div class="item safe" style="writing-mode: veritcal-rl; direction: ltr;" data-offset-x="15"></div>
+</div>
+
+<div class="container">
+  <div class="item safe" style="writing-mode: vertical-rl; direction: rtl;" data-offset-x="15"></div>
+</div>
+
+<div class="container">
+  <div class="item safe" style="writing-mode: vertical-lr; direction: ltr;" data-offset-x="15"></div>
+</div>
+
+<div class="container">
+  <div class="item safe" style="writing-mode: vertical-lr; direction: rtl;" data-offset-x="15"></div>
+</div>
+
+<!-- UNSAFE -->
+<br>
+
+<div class="container">
+  <div class="item unsafe" style="writing-mode: horizontal-tb; direction: ltr;" data-offset-x="-5"></div>
+</div>
+
+<div class="container">
+  <div class="item unsafe" style="writing-mode: horizontal-tb; direction: rtl;" data-offset-x="-5"></div>
+</div>
+
+<div class="container">
+  <div class="item unsafe" style="writing-mode: veritcal-rl; direction: ltr;" data-offset-x="-5"></div>
+</div>
+
+<div class="container">
+  <div class="item unsafe" style="writing-mode: vertical-rl; direction: rtl;" data-offset-x="-5"></div>
+</div>
+
+<div class="container">
+  <div class="item unsafe" style="writing-mode: vertical-lr; direction: ltr;" data-offset-x="-5"></div>
+</div>
+
+<div class="container">
+  <div class="item unsafe" style="writing-mode: vertical-lr; direction: rtl;" data-offset-x="-5"></div>
+</div>
+
+<!-- RTL -->
+<br>
+
+<div class="container rtl">
+  <div class="item safe" style="writing-mode: horizontal-tb; direction: ltr;" data-offset-x="-5"></div>
+</div>
+
+<div class="container rtl">
+  <div class="item safe" style="writing-mode: horizontal-tb; direction: rtl;" data-offset-x="-5"></div>
+</div>
+
+<div class="container rtl">
+  <div class="item safe" style="writing-mode: veritcal-rl; direction: ltr;" data-offset-x="-5"></div>
+</div>
+
+<div class="container rtl">
+  <div class="item safe" style="writing-mode: vertical-rl; direction: rtl;" data-offset-x="-5"></div>
+</div>
+
+<div class="container rtl">
+  <div class="item safe" style="writing-mode: vertical-lr; direction: ltr;" data-offset-x="-5"></div>
+</div>
+
+<div class="container rtl">
+  <div class="item safe" style="writing-mode: vertical-lr; direction: rtl;" data-offset-x="-5"></div>
+</div>
+
+<!-- UNSAFE RTL -->
+<br>
+
+<div class="container rtl">
+  <div class="item unsafe" style="writing-mode: horizontal-tb; direction: ltr;" data-offset-x="15"></div>
+</div>
+
+<div class="container rtl">
+  <div class="item unsafe" style="writing-mode: horizontal-tb; direction: rtl;" data-offset-x="15"></div>
+</div>
+
+<div class="container rtl">
+  <div class="item unsafe" style="writing-mode: veritcal-rl; direction: ltr;" data-offset-x="15"></div>
+</div>
+
+<div class="container rtl">
+  <div class="item unsafe" style="writing-mode: vertical-rl; direction: rtl;" data-offset-x="15"></div>
+</div>
+
+<div class="container rtl">
+  <div class="item unsafe" style="writing-mode: vertical-lr; direction: ltr;" data-offset-x="15"></div>
+</div>
+
+<div class="container rtl">
+  <div class="item unsafe" style="writing-mode: vertical-lr; direction: rtl;" data-offset-x="15"></div>
+</div>
+
diff --git a/testing/web-platform/tests/css/css-align/abspos/safe-justify-self-vlr.html b/testing/web-platform/tests/css/css-align/abspos/safe-justify-self-vlr.html
new file mode 100644
index 0000000000..7554975f1b
--- /dev/null
+++ b/testing/web-platform/tests/css/css-align/abspos/safe-justify-self-vlr.html
@@ -0,0 +1,149 @@
+<!DOCTYPE html>
+<link rel="help" href="https://drafts.csswg.org/css-align-3/#justify-abspos">
+<style>
+body {
+  margin: 0;
+}
+
+.container {
+  writing-mode: vertical-lr;
+  direction: ltr;
+  display: inline-block;
+  position: relative;
+  margin: 20px;
+  border: solid 4px;
+  width: 40px;
+  height: 40px;
+}
+
+.item {
+  position: absolute;
+  background: green;
+  inset: 5px;
+  margin: 10px;
+  width: 30px;
+  height: 30px;
+}
+
+.safe {
+  justify-self: safe end;
+}
+.unsafe {
+  justify-self: unsafe end;
+}
+
+.rtl {
+  direction: rtl;
+}
+</style>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/check-layout-th.js"></script>
+
+<body onload="checkLayout('.item')">
+
+<div class="container">
+  <div class="item safe" style="writing-mode: horizontal-tb; direction: ltr;" data-offset-y="15"></div>
+</div>
+
+<div class="container">
+  <div class="item safe" style="writing-mode: horizontal-tb; direction: rtl;" data-offset-y="15"></div>
+</div>
+
+<div class="container">
+  <div class="item safe" style="writing-mode: veritcal-rl; direction: ltr;" data-offset-y="15"></div>
+</div>
+
+<div class="container">
+  <div class="item safe" style="writing-mode: vertical-rl; direction: rtl;" data-offset-y="15"></div>
+</div>
+
+<div class="container">
+  <div class="item safe" style="writing-mode: vertical-lr; direction: ltr;" data-offset-y="15"></div>
+</div>
+
+<div class="container">
+  <div class="item safe" style="writing-mode: vertical-lr; direction: rtl;" data-offset-y="15"></div>
+</div>
+
+<!-- UNSAFE -->
+<br>
+
+<div class="container">
+  <div class="item unsafe" style="writing-mode: horizontal-tb; direction: ltr;" data-offset-y="-5"></div>
+</div>
+
+<div class="container">
+  <div class="item unsafe" style="writing-mode: horizontal-tb; direction: rtl;" data-offset-y="-5"></div>
+</div>
+
+<div class="container">
+  <div class="item unsafe" style="writing-mode: veritcal-rl; direction: ltr;" data-offset-y="-5"></div>
+</div>
+
+<div class="container">
+  <div class="item unsafe" style="writing-mode: vertical-rl; direction: rtl;" data-offset-y="-5"></div>
+</div>
+
+<div class="container">
+  <div class="item unsafe" style="writing-mode: vertical-lr; direction: ltr;" data-offset-y="-5"></div>
+</div>
+
+<div class="container">
+  <div class="item unsafe" style="writing-mode: vertical-lr; direction: rtl;" data-offset-y="-5"></div>
+</div>
+
+<!-- RTL -->
+<br>
+
+<div class="container rtl">
+  <div class="item safe" style="writing-mode: horizontal-tb; direction: ltr;" data-offset-y="-5"></div>
+</div>
+
+<div class="container rtl">
+  <div class="item safe" style="writing-mode: horizontal-tb; direction: rtl;" data-offset-y="-5"></div>
+</div>
+
+<div class="container rtl">
+  <div class="item safe" style="writing-mode: veritcal-rl; direction: ltr;" data-offset-y="-5"></div>
+</div>
+
+<div class="container rtl">
+  <div class="item safe" style="writing-mode: vertical-rl; direction: rtl;" data-offset-y="-5"></div>
+</div>
+
+<div class="container rtl">
+  <div class="item safe" style="writing-mode: vertical-lr; direction: ltr;" data-offset-y="-5"></div>
+</div>
+
+<div class="container rtl">
+  <div class="item safe" style="writing-mode: vertical-lr; direction: rtl;" data-offset-y="-5"></div>
+</div>
+
+<!-- UNSAFE RTL -->
+<br>
+
+<div class="container rtl">
+  <div class="item unsafe" style="writing-mode: horizontal-tb; direction: ltr;" data-offset-y="15"></div>
+</div>
+
+<div class="container rtl">
+  <div class="item unsafe" style="writing-mode: horizontal-tb; direction: rtl;" data-offset-y="15"></div>
+</div>
+
+<div class="container rtl">
+  <div class="item unsafe" style="writing-mode: veritcal-rl; direction: ltr;" data-offset-y="15"></div>
+</div>
+
+<div class="container rtl">
+  <div class="item unsafe" style="writing-mode: vertical-rl; direction: rtl;" data-offset-y="15"></div>
+</div>
+
+<div class="container rtl">
+  <div class="item unsafe" style="writing-mode: vertical-lr; direction: ltr;" data-offset-y="15"></div>
+</div>
+
+<div class="container rtl">
+  <div class="item unsafe" style="writing-mode: vertical-lr; direction: rtl;" data-offset-y="15"></div>
+</div>
+
diff --git a/testing/web-platform/tests/css/css-align/abspos/safe-justify-self-vrl.html b/testing/web-platform/tests/css/css-align/abspos/safe-justify-self-vrl.html
new file mode 100644
index 0000000000..fe2405cf79
--- /dev/null
+++ b/testing/web-platform/tests/css/css-align/abspos/safe-justify-self-vrl.html
@@ -0,0 +1,149 @@
+<!DOCTYPE html>
+<link rel="help" href="https://drafts.csswg.org/css-align-3/#justify-abspos">
+<style>
+body {
+  margin: 0;
+}
+
+.container {
+  writing-mode: vertical-rl;
+  direction: ltr;
+  display: inline-block;
+  position: relative;
+  margin: 20px;
+  border: solid 4px;
+  width: 40px;
+  height: 40px;
+}
+
+.item {
+  position: absolute;
+  background: green;
+  inset: 5px;
+  margin: 10px;
+  width: 30px;
+  height: 30px;
+}
+
+.safe {
+  justify-self: safe end;
+}
+.unsafe {
+  justify-self: unsafe end;
+}
+
+.rtl {
+  direction: rtl;
+}
+</style>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/check-layout-th.js"></script>
+
+<body onload="checkLayout('.item')">
+
+<div class="container">
+  <div class="item safe" style="writing-mode: horizontal-tb; direction: ltr;" data-offset-y="15"></div>
+</div>
+
+<div class="container">
+  <div class="item safe" style="writing-mode: horizontal-tb; direction: rtl;" data-offset-y="15"></div>
+</div>
+
+<div class="container">
+  <div class="item safe" style="writing-mode: veritcal-rl; direction: ltr;" data-offset-y="15"></div>
+</div>
+
+<div class="container">
+  <div class="item safe" style="writing-mode: vertical-rl; direction: rtl;" data-offset-y="15"></div>
+</div>
+
+<div class="container">
+  <div class="item safe" style="writing-mode: vertical-lr; direction: ltr;" data-offset-y="15"></div>
+</div>
+
+<div class="container">
+  <div class="item safe" style="writing-mode: vertical-lr; direction: rtl;" data-offset-y="15"></div>
+</div>
+
+<!-- UNSAFE -->
+<br>
+
+<div class="container">
+  <div class="item unsafe" style="writing-mode: horizontal-tb; direction: ltr;" data-offset-y="-5"></div>
+</div>
+
+<div class="container">
+  <div class="item unsafe" style="writing-mode: horizontal-tb; direction: rtl;" data-offset-y="-5"></div>
+</div>
+
+<div class="container">
+  <div class="item unsafe" style="writing-mode: veritcal-rl; direction: ltr;" data-offset-y="-5"></div>
+</div>
+
+<div class="container">
+  <div class="item unsafe" style="writing-mode: vertical-rl; direction: rtl;" data-offset-y="-5"></div>
+</div>
+
+<div class="container">
+  <div class="item unsafe" style="writing-mode: vertical-lr; direction: ltr;" data-offset-y="-5"></div>
+</div>
+
+<div class="container">
+  <div class="item unsafe" style="writing-mode: vertical-lr; direction: rtl;" data-offset-y="-5"></div>
+</div>
+
+<!-- RTL -->
+<br>
+
+<div class="container rtl">
+  <div class="item safe" style="writing-mode: horizontal-tb; direction: ltr;" data-offset-y="-5"></div>
+</div>
+
+<div class="container rtl">
+  <div class="item safe" style="writing-mode: horizontal-tb; direction: rtl;" data-offset-y="-5"></div>
+</div>
+
+<div class="container rtl">
+  <div class="item safe" style="writing-mode: veritcal-rl; direction: ltr;" data-offset-y="-5"></div>
+</div>
+
+<div class="container rtl">
+  <div class="item safe" style="writing-mode: vertical-rl; direction: rtl;" data-offset-y="-5"></div>
+</div>
+
+<div class="container rtl">
+  <div class="item safe" style="writing-mode: vertical-lr; direction: ltr;" data-offset-y="-5"></div>
+</div>
+
+<div class="container rtl">
+  <div class="item safe" style="writing-mode: vertical-lr; direction: rtl;" data-offset-y="-5"></div>
+</div>
+
+<!-- UNSAFE RTL -->
+<br>
+
+<div class="container rtl">
+  <div class="item unsafe" style="writing-mode: horizontal-tb; direction: ltr;" data-offset-y="15"></div>
+</div>
+
+<div class="container rtl">
+  <div class="item unsafe" style="writing-mode: horizontal-tb; direction: rtl;" data-offset-y="15"></div>
+</div>
+
+<div class="container rtl">
+  <div class="item unsafe" style="writing-mode: veritcal-rl; direction: ltr;" data-offset-y="15"></div>
+</div>
+
+<div class="container rtl">
+  <div class="item unsafe" style="writing-mode: vertical-rl; direction: rtl;" data-offset-y="15"></div>
+</div>
+
+<div class="container rtl">
+  <div class="item unsafe" style="writing-mode: vertical-lr; direction: ltr;" data-offset-y="15"></div>
+</div>
+
+<div class="container rtl">
+  <div class="item unsafe" style="writing-mode: vertical-lr; direction: rtl;" data-offset-y="15"></div>
+</div>
+
diff --git a/testing/web-platform/tests/css/css-align/abspos/stretch-intrinsic-size-htb-htb.html b/testing/web-platform/tests/css/css-align/abspos/stretch-intrinsic-size-htb-htb.html
new file mode 100644
index 0000000000..dc7df332e4
--- /dev/null
+++ b/testing/web-platform/tests/css/css-align/abspos/stretch-intrinsic-size-htb-htb.html
@@ -0,0 +1,100 @@
+<!DOCTYPE html>
+<link rel="help" href="https://drafts.csswg.org/css-align-3/#align-abspos">
+<link rel="help" href="https://drafts.csswg.org/css-align-3/#justify-abspos">
+<style>
+body {
+  margin: 0;
+}
+
+.container {
+  writing-mode: horizontal-tb;
+  display: inline-block;
+  position: relative;
+  margin: 20px;
+  border: solid 4px;
+  width: 60px;
+  height: 60px;
+}
+
+.item {
+  writing-mode: horizontal-tb;
+  position: absolute;
+  background: green;
+  inset: 5px 10px 5px 10px;
+}
+
+.child::before {
+  aspect-ratio: 1/1;
+  min-width: 20px;
+  min-height: 20px;
+  width: 100%;
+  height: 100%;
+  content: '';
+  display: block;
+}
+
+.ar {
+  aspect-ratio: 1/1;
+  min-width: 20px;
+  min-height: 20px;
+}
+</style>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/check-layout-th.js"></script>
+
+<body onload="checkLayout('.item')">
+
+<body>
+
+<div class="container">
+  <div class="item child" style="justify-self: start; align-self: start;" data-expected-width="20" data-expected-height="20"></div>
+</div>
+
+<div class="container">
+  <div class="item child" style="justify-self: stretch; align-self: start;" data-expected-width="40" data-expected-height="40"></div>
+</div>
+
+<div class="container">
+  <div class="item child" style="justify-self: start; align-self: stretch;" data-expected-width="50" data-expected-height="50"></div>
+</div>
+
+<div class="container">
+  <div class="item child" style="justify-self: stretch; align-self: stretch;" data-expected-width="40" data-expected-height="50"></div>
+</div>
+
+<br>
+
+<div class="container">
+  <div class="item ar" style="justify-self: start; align-self: start;" data-expected-width="20" data-expected-height="20"></div>
+</div>
+
+<div class="container">
+  <div class="item ar" style="justify-self: stretch; align-self: start;" data-expected-width="40" data-expected-height="40"></div>
+</div>
+
+<div class="container">
+  <div class="item ar" style="justify-self: start; align-self: stretch;" data-expected-width="50" data-expected-height="50"></div>
+</div>
+
+<div class="container">
+  <div class="item ar" style="justify-self: stretch; align-self: stretch;" data-expected-width="40" data-expected-height="50"></div>
+</div>
+
+<br>
+
+<div class="container">
+  <canvas width="10" height="10" class="item" style="justify-self: start; align-self: start;" data-expected-width="10" data-expected-height="10"></canvas>
+</div>
+
+<div class="container">
+  <canvas width="10" height="10" class="item" style="justify-self: stretch; align-self: start;" data-expected-width="40" data-expected-height="40"></canvas>
+</div>
+
+<div class="container">
+  <canvas width="10" height="10" class="item" style="justify-self: start; align-self: stretch;" data-expected-width="50" data-expected-height="50"></canvas>
+</div>
+
+<div class="container">
+  <canvas width="10" height="10" class="item" style="justify-self: stretch; align-self: stretch;" data-expected-width="40" data-expected-height="50"></canvas>
+</div>
diff --git a/testing/web-platform/tests/css/css-align/abspos/stretch-intrinsic-size-htb-vrl.html b/testing/web-platform/tests/css/css-align/abspos/stretch-intrinsic-size-htb-vrl.html
new file mode 100644
index 0000000000..cd2c9b9abc
--- /dev/null
+++ b/testing/web-platform/tests/css/css-align/abspos/stretch-intrinsic-size-htb-vrl.html
@@ -0,0 +1,100 @@
+<!DOCTYPE html>
+<link rel="help" href="https://drafts.csswg.org/css-align-3/#align-abspos">
+<link rel="help" href="https://drafts.csswg.org/css-align-3/#justify-abspos">
+<style>
+body {
+  margin: 0;
+}
+
+.container {
+  writing-mode: horizontal-tb;
+  display: inline-block;
+  position: relative;
+  margin: 20px;
+  border: solid 4px;
+  width: 60px;
+  height: 60px;
+}
+
+.item {
+  writing-mode: vertical-rl;
+  position: absolute;
+  background: green;
+  inset: 5px 10px 5px 10px;
+}
+
+.item::before {
+  aspect-ratio: 1/1;
+  min-width: 20px;
+  min-height: 20px;
+  width: 100%;
+  height: 100%;
+  content: '';
+  display: block;
+}
+
+.ar {
+  aspect-ratio: 1/1;
+  min-width: 20px;
+  min-height: 20px;
+}
+</style>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/check-layout-th.js"></script>
+
+<body onload="checkLayout('.item')">
+
+<body>
+
+<div class="container">
+  <div class="item" style="justify-self: start; align-self: start;" data-expected-width="20" data-expected-height="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: stretch; align-self: start;" data-expected-width="40" data-expected-height="40"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: start; align-self: stretch;" data-expected-width="50" data-expected-height="50"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: stretch; align-self: stretch;" data-expected-width="40" data-expected-height="50"></div>
+</div>
+
+<br>
+
+<div class="container">
+  <div class="item ar" style="justify-self: start; align-self: start;" data-expected-width="20" data-expected-height="20"></div>
+</div>
+
+<div class="container">
+  <div class="item ar" style="justify-self: stretch; align-self: start;" data-expected-width="40" data-expected-height="40"></div>
+</div>
+
+<div class="container">
+  <div class="item ar" style="justify-self: start; align-self: stretch;" data-expected-width="50" data-expected-height="50"></div>
+</div>
+
+<div class="container">
+  <div class="item ar" style="justify-self: stretch; align-self: stretch;" data-expected-width="40" data-expected-height="50"></div>
+</div>
+
+<br>
+
+<div class="container">
+  <canvas width="10" height="10" class="item" style="justify-self: start; align-self: start;" data-expected-width="10" data-expected-height="10"></canvas>
+</div>
+
+<div class="container">
+  <canvas width="10" height="10" class="item" style="justify-self: stretch; align-self: start;" data-expected-width="40" data-expected-height="40"></canvas>
+</div>
+
+<div class="container">
+  <canvas width="10" height="10" class="item" style="justify-self: start; align-self: stretch;" data-expected-width="50" data-expected-height="50"></canvas>
+</div>
+
+<div class="container">
+  <canvas width="10" height="10" class="item" style="justify-self: stretch; align-self: stretch;" data-expected-width="40" data-expected-height="50"></canvas>
+</div>
diff --git a/testing/web-platform/tests/css/css-align/abspos/stretch-intrinsic-size-vrl-htb.html b/testing/web-platform/tests/css/css-align/abspos/stretch-intrinsic-size-vrl-htb.html
new file mode 100644
index 0000000000..7b1002191f
--- /dev/null
+++ b/testing/web-platform/tests/css/css-align/abspos/stretch-intrinsic-size-vrl-htb.html
@@ -0,0 +1,100 @@
+<!DOCTYPE html>
+<link rel="help" href="https://drafts.csswg.org/css-align-3/#align-abspos">
+<link rel="help" href="https://drafts.csswg.org/css-align-3/#justify-abspos">
+<style>
+body {
+  margin: 0;
+}
+
+.container {
+  writing-mode: vertical-rl;
+  display: inline-block;
+  position: relative;
+  margin: 20px;
+  border: solid 4px;
+  width: 60px;
+  height: 60px;
+}
+
+.item {
+  writing-mode: horizontal-tb;
+  position: absolute;
+  background: green;
+  inset: 5px 10px 5px 10px;
+}
+
+.item::before {
+  aspect-ratio: 1/1;
+  min-width: 20px;
+  min-height: 20px;
+  width: 100%;
+  height: 100%;
+  content: '';
+  display: block;
+}
+
+.ar {
+  aspect-ratio: 1/1;
+  min-width: 20px;
+  min-height: 20px;
+}
+</style>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/check-layout-th.js"></script>
+
+<body onload="checkLayout('.item')">
+
+<body>
+
+<div class="container">
+  <div class="item" style="justify-self: start; align-self: start;" data-expected-width="20" data-expected-height="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: stretch; align-self: start;" data-expected-width="50" data-expected-height="50"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: start; align-self: stretch;" data-expected-width="40" data-expected-height="40"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: stretch; align-self: stretch;" data-expected-width="40" data-expected-height="50"></div>
+</div>
+
+<br>
+
+<div class="container">
+  <div class="item ar" style="justify-self: start; align-self: start;" data-expected-width="20" data-expected-height="20"></div>
+</div>
+
+<div class="container">
+  <div class="item ar" style="justify-self: stretch; align-self: start;" data-expected-width="50" data-expected-height="50"></div>
+</div>
+
+<div class="container">
+  <div class="item ar" style="justify-self: start; align-self: stretch;" data-expected-width="40" data-expected-height="40"></div>
+</div>
+
+<div class="container">
+  <div class="item ar" style="justify-self: stretch; align-self: stretch;" data-expected-width="40" data-expected-height="50"></div>
+</div>
+
+<br>
+
+<div class="container">
+  <canvas width="10" height="10" class="item" style="justify-self: start; align-self: start;" data-expected-width="10" data-expected-height="10"></canvas>
+</div>
+
+<div class="container">
+  <canvas width="10" height="10" class="item" style="justify-self: stretch; align-self: start;" data-expected-width="50" data-expected-height="50"></canvas>
+</div>
+
+<div class="container">
+  <canvas width="10" height="10" class="item" style="justify-self: start; align-self: stretch;" data-expected-width="40" data-expected-height="40"></canvas>
+</div>
+
+<div class="container">
+  <canvas width="10" height="10" class="item" style="justify-self: stretch; align-self: stretch;" data-expected-width="40" data-expected-height="50"></canvas>
+</div>
diff --git a/testing/web-platform/tests/css/css-align/abspos/stretch-intrinsic-size-vrl-vrl.html b/testing/web-platform/tests/css/css-align/abspos/stretch-intrinsic-size-vrl-vrl.html
new file mode 100644
index 0000000000..10f11a9f12
--- /dev/null
+++ b/testing/web-platform/tests/css/css-align/abspos/stretch-intrinsic-size-vrl-vrl.html
@@ -0,0 +1,100 @@
+<!DOCTYPE html>
+<link rel="help" href="https://drafts.csswg.org/css-align-3/#align-abspos">
+<link rel="help" href="https://drafts.csswg.org/css-align-3/#justify-abspos">
+<style>
+body {
+  margin: 0;
+}
+
+.container {
+  writing-mode: vertical-rl;
+  display: inline-block;
+  position: relative;
+  margin: 20px;
+  border: solid 4px;
+  width: 60px;
+  height: 60px;
+}
+
+.item {
+  writing-mode: vertical-rl;
+  position: absolute;
+  background: green;
+  inset: 5px 10px 5px 10px;
+}
+
+.item::before {
+  aspect-ratio: 1/1;
+  min-width: 20px;
+  min-height: 20px;
+  width: 100%;
+  height: 100%;
+  content: '';
+  display: block;
+}
+
+.ar {
+  aspect-ratio: 1/1;
+  min-width: 20px;
+  min-height: 20px;
+}
+</style>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/check-layout-th.js"></script>
+
+<body onload="checkLayout('.item')">
+
+<body>
+
+<div class="container">
+  <div class="item" style="justify-self: start; align-self: start;" data-expected-width="20" data-expected-height="20"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: stretch; align-self: start;" data-expected-width="50" data-expected-height="50"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: start; align-self: stretch;" data-expected-width="40" data-expected-height="40"></div>
+</div>
+
+<div class="container">
+  <div class="item" style="justify-self: stretch; align-self: stretch;" data-expected-width="40" data-expected-height="50"></div>
+</div>
+
+<br>
+
+<div class="container">
+  <div class="item ar" style="justify-self: start; align-self: start;" data-expected-width="20" data-expected-height="20"></div>
+</div>
+
+<div class="container">
+  <div class="item ar" style="justify-self: stretch; align-self: start;" data-expected-width="50" data-expected-height="50"></div>
+</div>
+
+<div class="container">
+  <div class="item ar" style="justify-self: start; align-self: stretch;" data-expected-width="40" data-expected-height="40"></div>
+</div>
+
+<div class="container">
+  <div class="item ar" style="justify-self: stretch; align-self: stretch;" data-expected-width="40" data-expected-height="50"></div>
+</div>
+
+<br>
+
+<div class="container">
+  <canvas width="10" height="10" class="item" style="justify-self: start; align-self: start;" data-expected-width="10" data-expected-height="10"></canvas>
+</div>
+
+<div class="container">
+  <canvas width="10" height="10" class="item" style="justify-self: stretch; align-self: start;" data-expected-width="50" data-expected-height="50"></canvas>
+</div>
+
+<div class="container">
+  <canvas width="10" height="10" class="item" style="justify-self: start; align-self: stretch;" data-expected-width="40" data-expected-height="40"></canvas>
+</div>
+
+<div class="container">
+  <canvas width="10" height="10" class="item" style="justify-self: stretch; align-self: stretch;" data-expected-width="40" data-expected-height="50"></canvas>
+</div>
diff --git a/testing/web-platform/tests/css/css-align/abspos/table-align-self-stretch.html b/testing/web-platform/tests/css/css-align/abspos/table-align-self-stretch.html
new file mode 100644
index 0000000000..bedd0a5695
--- /dev/null
+++ b/testing/web-platform/tests/css/css-align/abspos/table-align-self-stretch.html
@@ -0,0 +1,84 @@
+<!DOCTYPE html>
+<link rel="help" href="https://drafts.csswg.org/css-align-3/#align-abspos">
+<style>
+body {
+  margin: 0;
+}
+
+.container {
+  writing-mode: horizontal-tb;
+  display: inline-block;
+  position: relative;
+  margin: 20px;
+  border: solid 4px;
+  width: 40px;
+  height: 40px;
+}
+
+.item {
+  writing-mode: horizontal-tb;
+  position: absolute;
+  background: green;
+  inset: 5px;
+  align-self: stretch;
+  display: table;
+}
+
+.item::before {
+  content: '';
+  display: block;
+  width: 10px;
+  height: 20px;
+}
+
+.big::before {
+  width: 50px;
+  height: 60px;
+}
+
+.vrl {
+  writing-mode: vertical-rl;
+}
+</style>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/check-layout-th.js"></script>
+
+<body onload="checkLayout('.item')">
+
+<body>
+
+<div class="container">
+  <div class="item" data-expected-width="10" data-expected-height="30"></div>
+</div>
+
+<div class="container">
+  <div class="item big" data-expected-width="50" data-expected-height="60"></div>
+</div>
+
+<div class="container">
+  <div class="item vrl" data-expected-width="10" data-expected-height="30"></div>
+</div>
+
+<div class="container">
+  <div class="item big vrl" data-expected-width="50" data-expected-height="60"></div>
+</div>
+
+<br>
+
+<div class="container vrl">
+  <div class="item" data-expected-width="30" data-expected-height="20"></div>
+</div>
+
+<div class="container vrl">
+  <div class="item big" data-expected-width="50" data-expected-height="60"></div>
+</div>
+
+<div class="container vrl">
+  <div class="item vrl" data-expected-width="30" data-expected-height="20"></div>
+</div>
+
+<div class="container vrl">
+  <div class="item big vrl" data-expected-width="50" data-expected-height="60"></div>
+</div>
+
diff --git a/testing/web-platform/tests/css/css-align/abspos/table-justify-self-stretch.html b/testing/web-platform/tests/css/css-align/abspos/table-justify-self-stretch.html
new file mode 100644
index 0000000000..c409b10714
--- /dev/null
+++ b/testing/web-platform/tests/css/css-align/abspos/table-justify-self-stretch.html
@@ -0,0 +1,84 @@
+<!DOCTYPE html>
+<link rel="help" href="https://drafts.csswg.org/css-align-3/#justify-abspos">
+<style>
+body {
+  margin: 0;
+}
+
+.container {
+  writing-mode: horizontal-tb;
+  display: inline-block;
+  position: relative;
+  margin: 20px;
+  border: solid 4px;
+  width: 40px;
+  height: 40px;
+}
+
+.item {
+  writing-mode: horizontal-tb;
+  position: absolute;
+  background: green;
+  inset: 5px;
+  justify-self: stretch;
+  display: table;
+}
+
+.item::before {
+  content: '';
+  display: block;
+  width: 10px;
+  height: 20px;
+}
+
+.big::before {
+  width: 50px;
+  height: 60px;
+}
+
+.vrl {
+  writing-mode: vertical-rl;
+}
+</style>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/resources/check-layout-th.js"></script>
+
+<body onload="checkLayout('.item')">
+
+<body>
+
+<div class="container">
+  <div class="item" data-expected-width="30" data-expected-height="20"></div>
+</div>
+
+<div class="container">
+  <div class="item big" data-expected-width="50" data-expected-height="60"></div>
+</div>
+
+<div class="container">
+  <div class="item vrl" data-expected-width="30" data-expected-height="20"></div>
+</div>
+
+<div class="container">
+  <div class="item big vrl" data-expected-width="50" data-expected-height="60"></div>
+</div>
+
+<br>
+
+<div class="container vrl">
+  <div class="item" data-expected-width="10" data-expected-height="30"></div>
+</div>
+
+<div class="container vrl">
+  <div class="item big" data-expected-width="50" data-expected-height="60"></div>
+</div>
+
+<div class="container vrl">
+  <div class="item vrl" data-expected-width="10" data-expected-height="30"></div>
+</div>
+
+<div class="container vrl">
+  <div class="item big vrl" data-expected-width="50" data-expected-height="60"></div>
+</div>
+
-- 
cgit v1.2.3