css/css-contain/contain-layout-containing-block-fixed-001.html

<!DOCTYPE HTML>
<html>
<head>
  <meta charset="utf-8">
  <title>CSS Test: 'contain: layout' element should contain fixed position elements.</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">
  <link rel="help" href="https://drafts.csswg.org/css-contain-1/#containment-layout">
  <link rel="match" href="contain-paint-containing-block-fixed-001-ref.html">
  <style>
  #a {
      contain: layout;
      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>