chromium/third_party/blink/web_tests/external/wpt/css/css-anchor-position/anchor-position-dynamic-002.html

<!DOCTYPE html>
<link rel="help" href="https://drafts.csswg.org/css-anchor-1/#propdef-anchor-name">
<link rel="author" href="mailto:[email protected]">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="/resources/check-layout-th.js"></script>
<script src="support/test-common.js"></script>
<style>
#container {
  position: relative;
}
#anchor1 {
  anchor-name: --a1;
}
#anchor2 {
  anchor-name: --a2;
}
#anchor1, #anchor2 {
  width: 5px;
  height: 7px;
  background: orange;
}
.after #anchor1, .after #anchor2 {
  width: 10px;
}
.target {
  position: absolute;
}
</style>
<body>
  <div id="container">
    <!-- When the anchor is in the same containing block. -->
    <div id="anchor1"></div>
    <div class="target" style="left: anchor(--a1 right)" data-offset-x=5></div>
    <div class="target" style="width: anchor-size(--a1 width)" data-expected-width=5></div>

    <!-- When the anchor is in a different containing block. -->
    <div>
      <div id="anchor2"></div>
    </div>
    <div class="target" style="left: anchor(--a2 right)" data-offset-x=5></div>
    <div class="target" style="width: anchor-size(--a2 width)" data-expected-width=5></div>
  </div>
<script type="module">
await checkLayoutForAnchorPos('.target', false);
container.classList.add('after');
for (const element of document.getElementsByClassName('target')) {
  if (element.dataset.offsetX === '5')
    element.dataset.offsetX = '10';
  if (element.dataset.expectedWidth === '5')
    element.dataset.expectedWidth = '10';
}
await checkLayoutForAnchorPos('.after .target', true);
</script>
</body>