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chromium/third_party/blink/web_tests/external/wpt/css/css-anchor-position/position-visibility-anchors-visible-after-scroll-in-ref.html 

<!DOCTYPE html>
<meta charset="utf-8">
<style>
  #scroll-container {
    overflow: hidden scroll;
    width: 300px;
    height: 100px;
  }

  #anchor {
    width: 100px;
    height: 100px;
    background: orange;
    margin-bottom: 100px;
  }

  #target {
    width: 100px;
    height: 100px;
    background: green;
  }
</style>

<div id="scroll-container">
  <div id="anchor">anchor</div>
</div>
<div id="target">target</div>

<script>
  const scroller = document.getElementById('scroll-container');
  scroller.scrollTop = 0;
</script>