css/css-conditional/container-queries/conditional-container-status.html

<!doctype html>
<title>Conditionally removing container status</title>
<link rel="help" href="https://drafts.csswg.org/css-conditional-5/#container-type">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="support/cq-testcommon.js"></script>
<style>
  .parent { width: 300px; }
  .child { width: 100px; }
  .parent, .child { container-type: inline-size; }
  @container (min-width: 200px) {
    .child { container-type: initial; }
    .grandchild { border: 3px solid green }
  }
</style>
<div class="parent">
  <div class="child">
    <div class="grandchild">You should see a green border around this text</div>
  </div>
</div>
<script>
  setup(() => assert_implements_size_container_queries());

  test(function() {
    let s = getComputedStyle(document.querySelector('.grandchild'));
    assert_equals(s.getPropertyValue('border-color'), 'rgb(0, 128, 0)');
  }, 'Conditionally applying container-type:initial');
</script>