css/css-contain/content-visibility/content-visibility-with-top-layer-001.html

<!doctype html>
<html class="reftest-wait">
<meta charset="utf8">
<title>CSS Content Visibility: dialog doesn't show when hidden after render</title>
<link rel="author" title="Vladimir Levin" href="mailto:vmpstr@chromium.org">
<link rel="help" href="https://drafts.csswg.org/css-contain/#content-visibility">
<link rel="match" href="container-ref.html">
<meta name="assert" content="top layer dialogs don't render when in skipped subtrees">

<script src="/common/reftest-wait.js"></script>

<style>
.box { width: 150px; height: 150px; background: lightblue }
.hidden { content-visibility: hidden }
</style>

<div id=container class=box>
Fail
<dialog id=dialog>Fail<div id=inner></div></dialog>
</div>

<script>
function runTest() {
  container.classList.add("hidden");
  dialog.showModal();
  takeScreenshot();
}

onload = () => requestAnimationFrame(() => requestAnimationFrame(runTest));
</script>