chromium/third_party/blink/web_tests/external/wpt/css/css-contain/content-visibility/container-focus-ref.html

<!doctype HTML>
<html>
<meta charset="utf8">
<title>CSS Content Visibility: container (reference)</title>
<link rel="author" title="Vladimir Levin" href="mailto:[email protected]">
<link rel="help" href="https://drafts.csswg.org/css-contain/#content-visibility">

<style>
#container {
  width: 150px;
  height: 150px;
  background: lightblue;
}
</style>

<p>Test passes if the light blue box below has focus.
<div id=container tabindex=0></div>

<script>
onload = () => container.focus();
</script>