css/css-conditional/container-queries/container-units-small-viewport-fallback.html

<!doctype html>
<title>Container Relative Units: fall back to small viewport</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: 40px;
  }
</style>
<iframe id=iframe srcdoc="
  <style>
    #container {
      container-type: inline-size;
      width: 70px;
      height: 30px;
    }
    #target {
      left: 10cqw;
      top: 10cqh;
      right: 10cqi;
      bottom: 10cqb;
      margin-left: 10cqmax;
      margin-right: 10cqmin;
    }
  </style>
  <div id=container>
    <div id=target></div>
  </div>
"></iframe>

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

  function waitForLoad(w) {
    return new Promise(resolve => w.addEventListener('load', resolve));
  }

  promise_test(async () => {
    await waitForLoad(window);
    let inner_target = iframe.contentDocument.querySelector('#target');

    // Since there's an inline-size container, cqw/cqi should evaluate against
    // that.
    assert_equals(getComputedStyle(inner_target).left, '7px'); // 10cqw
    assert_equals(getComputedStyle(inner_target).right, '7px'); // 10cqi

    // However, there is no size container, so cqh/cqb should evaluate against
    // the small viewport size.
    assert_equals(getComputedStyle(inner_target).top, '4px'); // 10cqh
    assert_equals(getComputedStyle(inner_target).bottom, '4px'); // 10cqb

    assert_equals(getComputedStyle(inner_target).marginLeft, '7px'); // 10cqmax
    assert_equals(getComputedStyle(inner_target).marginRight, '4px'); // 10cqmin

    iframe.style = 'width:400px;height:80px';

    // Not affected by resize:
    assert_equals(getComputedStyle(inner_target).left, '7px'); // 10cqw
    assert_equals(getComputedStyle(inner_target).right, '7px'); // 10cqi

    // Affected:
    assert_equals(getComputedStyle(inner_target).top, '8px'); // 10cqh
    assert_equals(getComputedStyle(inner_target).bottom, '8px'); // 10cqb
    assert_equals(getComputedStyle(inner_target).marginLeft, '8px'); // 10cqmax
    assert_equals(getComputedStyle(inner_target).marginRight, '7px'); // 10cqmin
  }, 'Use small viewport size as fallback');
</script>