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diff --git a/testing/web-platform/tests/scroll-animations/css/progress-based-animation-timeline.html b/testing/web-platform/tests/scroll-animations/css/progress-based-animation-timeline.html
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+++ b/testing/web-platform/tests/scroll-animations/css/progress-based-animation-timeline.html
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+<!DOCTYPE html>
+<title>CSS Animation using progress based timeline</title>
+<link rel="help" src="https://drafts.csswg.org/css-animations-2/#animation-timeline">
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script src="/web-animations/testcommon.js"></script>
+<style>
+  main > div {
+    overflow: hidden;
+    width: 100px;
+    height: 100px;
+  }
+  main > div > div {
+    height: 200px;
+  }
+
+  @keyframes top {
+    from { top: 100px; }
+    to { top: 200px; }
+  }
+
+  #scroller1 {
+    scroll-timeline: top_timeline;
+  }
+
+  #element {
+    animation-name: top;
+    animation-duration: 10s;
+    animation-timing-function: linear;
+    animation-timeline: top_timeline;
+  }
+  /* Ensure stable expectations if feature is not supported */
+  @supports not (animation-timeline:foo) {
+    #element { animation-play-state: paused; }
+  }
+</style>
+<main>
+  <div id=scroller1><div></div></div>
+  <div id=element></div>
+</main>
+<script>
+  window.onload = async () => {
+    promise_test(async (t) => {
+      await waitForNextFrame();
+      const anim = document.getAnimations()[0];
+      await anim.ready;
+      scroller1.scrollTop = 20;
+      await waitForNextFrame();
+      assert_equals(getComputedStyle(element).top, '120px');
+    }, 'progress based animation timeline works');
+  };
+</script>