css/css-contain/content-visibility/content-visibility-paint-containment-001.html

<!DOCTYPE html>
<html>
<meta charset="utf-8">
<title>content-visibility and paint containment</title>
<link rel="help" href="https://drafts.csswg.org/css-contain/#contain-property">
<link rel="help" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1765615">
<meta name="assert" content="Verify paint containment is implied by content-visibility.">
<link rel="match" href="content-visibility-paint-containment-001-ref.html">

<style>
  .container {
      width: 100px;
      height: 100px;
      background: green;
  }
  .hidden {
      content-visibility: hidden;
  }
  .visible {
      content-visibility: visible;
  }
  #overflowing {
      width: 400px;
      height: 100px;
  }
  .square {
      display: inline-block;
      width: 50px;
      height: 50px;
      margin: 5px;
  }
  .red {
      background: red;
  }
  .green {
      background: green;
  }
</style>

<body>
  <p>PASS if you see a green square and no red.</p>
  <div class="hidden container">
    <div id="overflowing"><div class="square"></div><div class="square"></div><div class="red square"></div></div>
  </div>
  <p>PASS if you see <em>two</em> green squares.</p>
  <div class="visible container">
    <div id="overflowing"><div class="square"></div><div class="square"></div><div class="green square"></div></div>
  </div>
</body>
</html>