<!DOCTYPE html>

<html>
  <style>
    body {
      overflow: hidden;
    }
    .container {
      width: 500px;
      height: 300px;
      -webkit-column-count: 2;
      -webkit-column-fill: auto;
      column-count: 2;
      column-fill: auto;
      border: 1px solid black;
    }
    
    .block {
      display: inline-block;
      width: 200px;
      height: 50px;
      margin: 10px;
      background-color: silver;
      outline: 5px solid transparent; /* increases compositing layer bounds to test bounds math */
    }
    
    .composited {
      -webkit-transform: translateZ(0);
      background-color: blue;
    }
    
    .box {
      height: 50px;
      width: 50px;
      background-color: green;
    }

    #layers {
      opacity: 0; /* hide from pixel result */
    }
  </style>
  <script>
    if (window.testRunner)
      testRunner.dumpAsText(true);
    
    function dumpLayers()
    {
      if (window.testRunner)
        document.getElementById('layers').innerText = window.internals.layerTreeAsText(document);
    }
    
    window.addEventListener('load', dumpLayers, false);
  </script>
<head>
</head>
<body>

  <div class="container">
    <div class="block"></div>
    <div class="block"></div>
    <div class="composited block">
      <div class="composited box"></div>
    </div>
    <div class="block"></div>
    <div class="block"></div>
    <div class="composited block">
      <div class="composited box"></div>
    </div>
    <div class="block"></div>
    <div class="block"></div>
  </div>
  
<pre id="layers">Layer tree goes here in DRT</pre>
</body>
</html>