css/css-conditional/container-queries/container-units-media-queries.html

<!DOCTYPE html>
<title>Container-relative units in @media</title>
<link rel="help" href="https://drafts.csswg.org/css-conditional-5/#container-lengths">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="support/cq-testcommon.js"></script>

<style>
  iframe {
    width: 200px;
    height: 100px;
  }
</style>

<iframe id=iframe></iframe>

<script>
setup(() => assert_implements_size_container_queries());

const doc = iframe.contentDocument;
const win = iframe.contentWindow;

function test_media_query(feature, result, description) {
  test((t) => {
    t.add_cleanup(() => { doc.body.innerHTML = ''; })
    doc.body.innerHTML = `
      <style>
        body {
          color: red;
        }
        @media (${feature}) {
          body {
            color: green;
          }
        }
      </style>
      `;
    assert_equals(win.getComputedStyle(doc.body).color, result);
  }, description);
}

function test_media_query_applies(feature) {
  test_media_query(feature, 'rgb(0, 128, 0)', `@media(${feature}) applies`);
}

function test_media_query_does_not_apply(feature) {
  test_media_query(feature, 'rgb(255, 0, 0)', `@media(${feature}) does not apply`);
}

// Container-relative units resolve against the "small viewport size" for
// media queries.
test_media_query_applies('width:100cqw');
test_media_query_applies('width:100cqi');
test_media_query_applies('width:100cqmax');
test_media_query_applies('height:100cqh');
test_media_query_applies('height:100cqb');
test_media_query_applies('height:100cqmin');
test_media_query_does_not_apply('width:90cqw');
test_media_query_does_not_apply('height:90cqh');

</script>