contain-layout-formatting-context-margin-001.html

<!DOCTYPE HTML>
<html>
<head>
  <meta charset="utf-8">
  <title>CSS Test: 'contain: layout' with a vertical margin child. Margin collapse should not occur, and neither should overflow clipping.</title>
  <link rel="author" title="Kyle Zentner" href="mailto:[email protected]">
  <link rel="author" title="Morgan Rae Reschenberg" href="mailto:[email protected]">
  <link rel="help" href="https://drafts.csswg.org/css-contain/#containment-layout">
  <link rel="match" href="contain-layout-formatting-context-margin-001-ref.html">
  <style>
  #a {
      contain:layout;
      background: blue;
      margin: 10px;
      width: 50px;
      height: 50px;
  }
  #b {
      width: 50px;
      height: 40px;
      background: green;
      margin-top: 10px;
  }
  #c {
      background: lightblue;
      width: 50px;
      height: 10px;
  }
  </style>
</head>
<body>
  <div id="a">
    <div id="b"></div>
    <div id="c"></div>
  </div>
</body>
</html>

chromium/third_party/blink/web_tests/external/wpt/css/css-contain/contain-layout-formatting-context-margin-001.html