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diff --git a/testing/web-platform/tests/css/css-scroll-anchoring/anchor-updates-after-explicit-scroll.html b/testing/web-platform/tests/css/css-scroll-anchoring/anchor-updates-after-explicit-scroll.html
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+++ b/testing/web-platform/tests/css/css-scroll-anchoring/anchor-updates-after-explicit-scroll.html
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+<!DOCTYPE html>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<style>
+
+#scroller {
+  height: 200px;
+  width: 200px;
+  overflow: scroll;
+}
+#a1, #space1, #a2, #space2 {
+  height: 200px;
+}
+#a1, #a2 {
+  background-color: #8f8;
+}
+
+</style>
+<div id="scroller">
+  <div id="space0"></div>
+  <div id="a1"></div>
+  <div id="space1"></div>
+  <div id="a2"></div>
+  <div id="space2"></div>
+</div>
+<script>
+
+// Tests that the anchor node is recomputed after an explicit change to the
+// scroll position.
+
+test(() => {
+  var scroller = document.querySelector("#scroller");
+  scroller.scrollTop = 500;
+
+  // We should now be anchored to #a2.
+  document.querySelector("#space1").style.height = "300px";
+  assert_equals(scroller.scrollTop, 600);
+
+  scroller.scrollTop = 100;
+
+  // We should now be anchored to #a1. Make sure there is no adjustment from
+  // moving #a2.
+  document.querySelector("#space1").style.height = "400px";
+  assert_equals(scroller.scrollTop, 100);
+
+  // Moving #a1 should produce an adjustment.
+  document.querySelector("#space0").style.height = "100px";
+  assert_equals(scroller.scrollTop, 200);
+}, "Anchor node recomputed after an explicit scroll occurs.");
+
+</script>