css/selectors/is-specificity-shadow.html

<!DOCTYPE html>
<title>Specificity of :host() inside :is()</title>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<link rel="help" href="https://drafts.csswg.org/selectors-4/#matches">
<link rel="help" href="https://drafts.csswg.org/css-scoping/#host-selector">
<style>
  main :not(:is(:host(#a))) { color: green; }
  main :not(:is(:host(.a))) { color: red; }
</style>
<main>
  <div id=element>Green</div>
</main>
<script>
  test(function() {
    assert_equals(getComputedStyle(element).color, 'rgb(0, 128, 0)');
  }, 'Specificity of :host() inside :is()');
</script>