chromium/third_party/blink/web_tests/external/wpt/css/css-transforms/individual-transform/stacking-context-001.html

<!DOCTYPE html>
<html class="reftest-wait">
  <head>
    <title>
      Individual transform properties' animations create stacking context in delay phase
    </title>
    <link rel="help" href="https://drafts.csswg.org/css-transforms-2/#individual-transforms">
    <link rel="match" href="stacking-context-ref.html">
    <meta name="assert" content="Individual transform properties' animations
                                 should create stacking context even in delay
                                 phase."/>
    <style>
      #back {
        height: 100px;
        width: 100px;
        position: fixed;
        background: green;
        margin-top: 50px;
      }
      @keyframes scale {
        from, to { scale: 1; }
      }
      #test {
        width: 100px;
        height: 100px;
        background: blue;
        animation: scale 100s 100s;
      }
    </style>
  </head>
  <body>
    <div id="back"></div>
    <div id="test"></div>
  </body>
  <script>
    requestAnimationFrame(() => {
      document.documentElement.classList.remove('reftest-wait');
    });
  </script>
</html>