containing-block-creation.html | Explore in Territory

<!DOCTYPE html>
<html>
<head>
  <style>
    #willChangeTop {
      will-change: top;
      position: absolute;
      left: 200px;
      top: 100px;
      width: 100px;
      height: 100px;
      background-color: blue;
      color: white;
    }

    #willChangeTransform {
      will-change: -webkit-transform;
      position: absolute;
      left: 200px;
      top: 300px;
      width: 100px;
      height: 100px;
      background-color: blue;
      color: white;
    }

    .fixed {
      position: fixed;
      left: 50px;
      top: 50px;
      width: 75px;
      height: 75px;
      background-color: green
    }
  </style>
</head>

<body>
  This test verifies that "will-change: -webkit-transform" creates a containing
  block for fixed position descendants, and that other values of will-change do
  not create such a containing block.
  <div id="willChangeTop">
    will-change: top
    <div class="fixed"></div>
  </div>
  <div id="willChangeTransform">
    will-change: -webkit-transform
    <div class="fixed"></div>
  </div>
</body>

</html>

chromium/third_party/blink/web_tests/compositing/will-change/containing-block-creation.html