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diff --git a/testing/web-platform/tests/css/css-contain/contain-subgrid-001.html b/testing/web-platform/tests/css/css-contain/contain-subgrid-001.html
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index 0000000000..59a104bfba
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+++ b/testing/web-platform/tests/css/css-contain/contain-subgrid-001.html
@@ -0,0 +1,45 @@
+<!doctype html>
+<html lang=en>
+  <meta charset=utf-8>
+  <title>CSS-contain test: layout/paint containment on subgrid</title>
+  <link rel="author" title="Mats Palmgren" href="mailto:mats@mozilla.com">
+  <meta name=assert content="layout/paint containment inhibits subgrid">
+  <link rel="match" href="reference/contain-subgrid-001.html">
+  <link rel=help href="https://drafts.csswg.org/css-contain/#containment-layout">
+  <link rel=help href="https://drafts.csswg.org/css-contain/#containment-paint">
+  <link rel=help href="https://drafts.csswg.org/css-grid-2/">
+
+<style>
+.grid {
+  display: grid;
+  width: 40px;
+  height: 40px;
+  grid: [a] repeat(2,15px) [b] / [a] repeat(2,15px) [b];
+  gap: 10px;
+}
+
+.subgrid {
+  display: grid;
+  grid: subgrid;
+  background: lightgrey;
+  grid-area:1/1/3/3;
+}
+
+.layout { contain: layout; }
+.paint { contain: paint; }
+
+.inner {
+  background: blue;
+  grid-area:a/a/b/b;
+}
+.p {
+  place-self: start;
+  width:100%;
+  height:100%;
+}
+</style>
+
+<div class="grid"><div class="subgrid layout"><div class="inner"></div></div></div>
+<div class="grid"><div class="subgrid paint"><div class="inner"></div></div></div>
+<div class="grid"><div class="subgrid layout"><div class="inner p"></div></div></div>
+<div class="grid"><div class="subgrid paint"><div class="inner p"></div></div></div>