chromium/third_party/blink/web_tests/external/wpt/css/css-position/sticky/position-sticky-change-top.html

<!DOCTYPE html>
<html class='reftest-wait'>
<title>Sticky elements should invalidate when top/left/bottom/right changes</title>
<link rel="match" href="position-sticky-change-top-ref.html" />
<link rel="help" href="https://www.w3.org/TR/css-position-3/#sticky-pos" />
<link rel="help" href="https://crbug.com/939632">
<meta name="assert" content="This test checks that sticky elements are invalidated correctly when top/left/bottom/right change "/>

<script src="/common/reftest-wait.js"></script>
<script src="../resources/ref-rectangle.js"></script>

<!--
  It is important for this test that the sticky element is viewport-bound, and
  that multiple animation frames pass before changing the style.
-->
<style>
.marker {
  background: red;
  position: absolute;
  top: 200px;
  height: 100px;
  width: 100px;
}

.sticky {
  /* Triggers promotion without creating stacking context. */
  backface-visibility: hidden;
  background: green;
  position: sticky;
  top: 0;
  width: 100px;
  height: 100px;
}

.spacer {
  height: 200vh;
}
</style>
<div class="marker"></div>

<div class="sticky"></div>
<div class="spacer"></div>

<script>
requestAnimationFrame(() => {
  requestAnimationFrame(() => {
    document.querySelector('.sticky').style.setProperty('top', '200px');
    createIndicatorForStickyElements(document.querySelectorAll('.sticky'));
    takeScreenshot();
  });
});
</script>
</html>