css/css-contain/content-visibility/content-visibility-paint-containment-003.html

<!DOCTYPE html>
<html class="reftest-wait">
<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 properly updated after dynamic change to the content-visibility property.">
<link rel="match" href="content-visibility-paint-containment-003-ref.html">

<script src="/common/reftest-wait.js"></script>
<script src="/common/rendering-utils.js"></script>

<style>
  #container {
      width: 100px;
      height: 100px;
      background: green;
      content-visibility: hidden;
      /* Dynamic modification of content-visibility may change whether style
         containment is applied, which in turn may cause drastic invalidations
         (e.g. rebuilding counters). Make the test more robust by forcing
         style containment to always apply. */
      contain: style;
  }
  #overflowing {
      width: 400px;
      height: 100px;
  }
  .square {
      display: inline-block;
      width: 50px;
      height: 50px;
      margin: 5px;
  }
  .green {
      background: green;
  }
</style>

<body>
  <p>PASS if you see <em>two</em> green squares.</p>
  <div id="container">
    <div id="overflowing"><div class="square"></div><div class="square"></div><div class="green square"></div></div>
  </div>
  <script>
    window.addEventListener("TestRendered", async () => {
        container.style.contentVisibility = "visible";
        await waitForAtLeastOneFrame();
        takeScreenshot();
    });
  </script>
</body>
</html>