chromium/third_party/blink/web_tests/external/wpt/css/css-position/invalidate-opacity-negative-z-index.html

<!DOCTYPE html>
<html class="reftest-wait">
  <link rel="help" href="https://www.w3.org/TR/CSS2/visuren.html#propdef-z-index">
  <link rel="help" href="https://www.w3.org/TR/compositing-1/">
  <link rel="author" title="Chris Harrelson" href="mailto:[email protected]">
  <link rel="match" href="invalidate-opacity-negative-z-index-ref.html">

  <div style="position: relative; will-change: transform; z-index: -1"></div>
  <div id="target"
       style="width: 50px; height: 50px; background: blue; opacity: 0.2"></div>
  <script>
    onload = () => {
      requestAnimationFrame(() => requestAnimationFrame(() => {
          target.style.opacity = 0.99;
          document.documentElement.className = "";
      }));
    };
  </script>
</html>