css/css-scoping/host-defined.html

<!DOCTYPE html>
<meta charset="utf-8">
<title>Shadow host is considered, but does not match :defined</title>
<link rel="author" title="Steinar H. Gunderson" href="mailto:sesse@chromium.org">
<link rel="help" href="https://crbug.com/332587538">
<link rel="help" href="https://drafts.csswg.org/selectors/#featureless">
<link rel="match" href="/css/reference/ref-filled-green-100px-square-only.html">
<p>Test passes if there is a filled green square.</p>
<div id="host"></div>
<script>
  host.attachShadow({mode: "open"}).innerHTML = `
    <style>
      :host div {
        width: 100px;
        height: 100px;
        background-color: green;
      }
      :not(:defined) div {
        background-color: red;
      }
    </style>
    <div></div>
  `;
</script>