no-layout-containment-fixedpos-dynamic.html

<!DOCTYPE html>
<title>Position fixed elements should propagate from a container-type subtree.</title>
<link rel="help" href="https://github.com/w3c/csswg-drafts/issues/10544#issuecomment-2248438355">
<link rel="match" href="/css/reference/ref-filled-green-100px-square-only.html">
<style>
@container (width = 100px) {
  #test {
    position: fixed;
    inset: 0;
    background: green;
  }
}
</style>
<p>Test passes if there is a filled green square.</p>
<div id="target" style="contain: layout; width: 200px; height: 100px; background: red;">
  <div style="container-type: inline-size; height: 0;">
    <div id="test"></div>
  </div>
</div>
<script>
document.body.offsetTop;
document.getElementById('target').style.width = '100px';
</script>

chromium/third_party/blink/web_tests/external/wpt/css/css-conditional/container-queries/no-layout-containment-fixedpos-dynamic.html