testing/web-platform/tests/css/css-contain/content-visibility/spacer-with-top-layer-ref.html

<!doctype html>
<meta charset="utf8">
<title>CSS Content Visibility: dialog shows under c-v auto (ref)</title>
<style>
.box { width: 100px; height: 100px; border: 1px solid black; }
.spacer { width: 10px; height: 3000px; background: lightblue; }

</style>

<div class=spacer></div>
<div id=container class=box>
content
<dialog id=dialog>PASS<div id=inner></div></dialog>
</div>

<script>
dialog.showModal();
</script>