<!DOCTYPE HTML>
<html>
<head>
  <meta charset="utf-8">
  <title>CSS Reftest Reference</title>
  <link rel="author" title="Kyle Zentner" href="mailto:zentner.kyle@gmail.com">
  <link rel="author" title="Morgan Rae Reschenberg" href="mailto:mreschenberg@berkeley.edu">
  <style>
  #a {
    display: contents;
    width: 100px;
    height: 100px;
    background: red;
    margin: 50px;
  }
  #b {
    position: fixed;
    top: 0;
    left: 0;
    width: 100px;
    height: 100px;
    background: green;
  }
  </style>
</head>
<body>
  <div id="a">
    <div>
      <div id="b"></div>
    </div>
  </div>
</body>
</html>