chromium/third_party/blink/web_tests/external/wpt/css/css-anchor-position/anchor-scroll-chained-fallback.html

<!DOCTYPE html>
<title>Tests scroll adjustments of element anchored to another anchored element with fallback</title>
<link rel="author" href="mailto:[email protected]">
<link rel="help" href="https://drafts.csswg.org/css-anchor-1/">
<link rel="match" href="reference/anchor-scroll-chained-fallback-ref.html">
<style>
body {
  margin: 0;
}

div {
  width: 100px;
  height: 100px;
}

#scroller {
  overflow: scroll;
  width: 300px;
  height: 300px;
}

#anchor {
  anchor-name: --a1;
  background: orange;
  margin: 250px 0;
}

#anchored1 {
  position: absolute;
  position-anchor: --a1;
  background: green;
  position-try-fallbacks: --fallback;
  anchor-name: --a2;
  left: anchor(left);
  bottom: anchor(top);
}

#anchored2 {
  position: absolute;
  position-anchor: --a2;
  left: anchor(left);
  top: anchor(bottom);
  background: lime;
}

@position-try --fallback {
  left: anchor(right);
  top: anchor(top);
  bottom: auto;
}

</style>

<div id="scroller">
  <div id="anchor"></div>
</div>
<div id="anchored1"></div>
<div id="anchored2"></div>

<script>
scroller.scrollTop = 200;
</script>