chromium/third_party/blink/web_tests/external/wpt/css/css-scoping/shadow-link-rel-stylesheet.html

<!doctype html>
<title>CSS Test: &lt;link rel="stylesheet"&gt; in Shadow DOM</title>
<link rel="help" href="https://html.spec.whatwg.org/#link-type-stylesheet">
<link rel="match" href="reference/green-box.html">
<p>Test passes if you see a single 100px by 100px green box below.</p>
<div id="host">FAIL</div>
<script>
  host.attachShadow({ mode: "open" }).innerHTML = `
    <link rel="stylesheet" href="resources/host-green-box.css">
  `;
</script>