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diff --git a/testing/web-platform/tests/css/css-contain/container-queries/pseudo-elements-004.html b/testing/web-platform/tests/css/css-contain/container-queries/pseudo-elements-004.html
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+++ b/testing/web-platform/tests/css/css-contain/container-queries/pseudo-elements-004.html
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+<!doctype html>
+<title>@container: originating element container for pseudo elements</title>
+<link rel="help" href="https://drafts.csswg.org/css-contain-3/#container-queries">
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="support/cq-testcommon.js"></script>
+<style>
+  #target { container-type: inline-size; }
+  #target::before,
+  #target::after,
+  #target::marker,
+  #target::first-line,
+  #target::first-letter,
+  #target::backdrop {
+    color: red;
+  }
+  @container (width >= 300px) {
+    #target::before,
+    #target::after,
+    #target::marker,
+    #target::first-line,
+    #target::first-letter,
+    #target::backdrop {
+      color: green;
+    }
+  }
+</style>
+<div id="outer" style="width: 200px">
+  <div id="target"></div>
+</div>
+<script>
+  setup(() => assert_implements_container_queries());
+
+  const green = "rgb(0, 128, 0)";
+  const red = "rgb(255, 0, 0)";
+
+  const pseudo_elements = ["::before", "::after", "::marker", "::first-line", "::first-letter", "::backdrop"];
+
+  pseudo_elements.forEach((pseudo_element) => {
+    test(() => {
+      assert_equals(getComputedStyle(target, pseudo_element).color, red);
+    }, `Initial color for ${pseudo_element}`);
+  });
+
+  outer.style.width = "300px";
+
+  pseudo_elements.forEach((pseudo_element) => {
+    test(() => {
+      assert_equals(getComputedStyle(target, pseudo_element).color, green);
+    }, `Color for ${pseudo_element} depending on container`);
+  });
+</script>