css/css-view-transitions/scroller.html

<!DOCTYPE html>
<html class=reftest-wait>
<title>View transitions: scroller element</title>
<link rel="help" href="https://www.w3.org/TR/css-view-transitions-1/">
<link rel="author" href="mailto:vmpstr@chromium.org">
<link rel="match" href="scroller-ref.html">
<meta name="fuzzy" content="maxDifference=0-5; totalPixels=0-10">
<script src="/common/reftest-wait.js"></script>

<style>
#scroller {
  overflow: scroll;
  width: 100px;
  height: 100px;
  background: blue;
  view-transition-name: target;
}

#child {
  position: relative;
  width: 1000px;
  height: 1000px;
  background: green;
}

html::view-transition-group(root) { animation-duration: 300s; }
html::view-transition-old(target) {
  animation: unset;
  opacity: 1;
}
html::view-transition-new(target) {
  animation: unset;
  opacity: 0;
}
</style>

<div id="scroller">
  <div id="child"></div>
</div>

<script>
failIfNot(document.startViewTransition, "Missing document.startViewTransition");

function runTest() {
  scroller.scrollTop = 300;

  let transition = document.startViewTransition();
  transition.ready.then(() => requestAnimationFrame(takeScreenshot));
}

onload = () => requestAnimationFrame(() => requestAnimationFrame(runTest));
</script>