chromium/third_party/blink/web_tests/wpt_internal/css/css-anchor-position-inset-area-old/position-visibility-anchors-visible-non-intervening-container.html

<!DOCTYPE html>
<meta charset="utf-8">
<meta name="assert" content="position-visibility: anchors-visible should consider the visibility of the anchor relative the containing scroller, ignoring visibility in other scrollers." />
<title>CSS Anchor Positioning Test: position-visibility: anchors-visible</title>
<link rel="help" href="https://drafts.csswg.org/css-anchor-position-1/#position-visibility">
<link rel="match" href="position-visibility-anchors-visible-non-intervening-container-ref.html">
<style>
  #non-intervening-scroll-container {
    overflow: hidden;
    width: 200px;
    height: 200px;
    position: relative;
  }

  #position-container {
    position: relative;
  }

  #scroll-container {
    overflow: hidden scroll;
    width: 400px;
    height: 100px;
  }

  #anchor {
    anchor-name: --a1;
    width: 100px;
    height: 100px;
    background: orange;
  }

  #spacer {
    height: 100px;
  }

  #target {
    position-anchor: --a1;
    position-visibility: anchors-visible;
    inset-area: right;
    width: 100px;
    height: 100px;
    background: green;
    position: absolute;
    top: 0;
    left: 0;
  }
</style>

<div id="non-intervening-scroll-container">
  <div id="position-container">
    <div id="scroll-container">
      <!-- The anchor is not visible to the screen, but it is visible in the -->
      <!-- containing block of anchor1 and target1, so the target should not -->
      <!-- be hidden due to position-visibility: anchors-visible. -->
      <div id="anchor">anchor</div>
      <div id="spacer"></div>
      <div id="target">target</div>
    </div>
  </div>
</div>

<script>
  const non_intervening_scroller = document.getElementById('non-intervening-scroll-container');
  non_intervening_scroller.scrollLeft = 100;
</script>