css/css-break/change-block-background.html

<!DOCTYPE html>
<html class="reftest-wait">
  <link rel="author" title="Morten Stenshorne" href="mailto:mstensho@chromium.org">
  <link rel="help" href="https://bugs.chromium.org/p/chromium/issues/detail?id=1278652">
  <link rel="match" href="../reference/ref-filled-green-100px-square.xht">
  <p>Test passes if there is a filled green square and <strong>no red</strong>.</p>
  <div style="columns:5; column-gap:0; column-fill:auto; width:100px; height:100px;">
    <div style="height:200px; background:green;"></div>
    <div id="elm" style="height:300px; background:red;"></div>
  </div>
  <script>
    requestAnimationFrame(()=> {
      requestAnimationFrame(()=> {
        elm.style.background = "green";
        document.documentElement.classList.remove("reftest-wait");
      });
    });
  </script>
</html>