<!DOCTYPE html>

<html lang="en">
<head>
  <style>
    .box {
      position: absolute;
      height: 50px;
      width: 100px;
      left: 20px;
      background-color: black;
      outline: 4px solid gray;
      -webkit-filter: invert();
    }
    
  </style>
  <script>
    if (window.testRunner)
      window.testRunner.dumpAsText(true);
  </script>
</head>
<body>

  <!-- You should see an outlined white rectangle with a black one beneath it. -->
  <div class="box">
    <div class="box" style="top: 60px; left: 0"></div>
  </div>

</body>
</html>