1 files changed, 43 insertions, 0 deletions
diff --git a/testing/web-platform/tests/css/css-contain/contain-layout-020.html b/testing/web-platform/tests/css/css-contain/contain-layout-020.html
new file mode 100644
index 0000000000..655d4431d8
--- /dev/null
+++ b/testing/web-platform/tests/css/css-contain/contain-layout-020.html
@@ -0,0 +1,43 @@
+<!DOCTYPE html>
+<html class="reftest-wait">
+<meta charset=utf-8>
+<title>CSS Containment Test: Removing layout containment and contained positioned elements</title>
+<link rel="help" href="https://drafts.csswg.org/css-contain-1/#containment-layout">
+<link rel="match" href="reference/contain-layout-020-ref.html">
+<meta name=assert content="Removing layout containment relayouts contained positioned elements correctly.">
+
+<style>
+#container {
+    width: 300px;
+    height: 300px;
+    contain: layout;
+}
+.box {
+    width: 100px;
+    height: 100px;
+    background-color: green;
+}
+.fixed {
+    position: fixed;
+    top: 0;
+    left: 0;
+}
+.abspos {
+    position: absolute;
+    top: 0;
+    right: 0;
+}
+</style>
+
+<div id="container">
+  <div class="fixed box"></div>
+  <div class="abspos box"></div>
+</div>
+
+<script>
+  requestAnimationFrame(() => {
+    container.style.contain = "none";
+    document.documentElement.removeAttribute("class");
+  });
+</script>
+