chromium/third_party/blink/web_tests/compositing/sub-layer-focus-ring.html

<!DOCTYPE html>
<html>
<head>
<style>
.composited {
  will-change: transform;
}

.outer {
  position: absolute;
  width: 500px;
  height: 300px;
  top: 60px;
  left: 100px;
  background-color: yellow;
}

.outlined {
  outline: red auto thin;
  width: 150px;
  height: 50px;
  background-color: lightgrey;
}

.inner {
  width: 80px;
  height: 100px;
}
</style>
</head>
<body>
  <!-- The focus ring parts for the sub-layers should be at correct position,
       regardless whether the inner layer is composited. -->
  <div class="composited outer">
    <div class="outlined">
      <div class="composited inner"></div>
    </div>
  </div>
</body>
</html>