css/css-contain/content-visibility/dynamic-change-paint-fully-obscuring-child-001.html

<!DOCTYPE HTML>
<html class="reftest-wait">
<title>content-visibility:hidden elements painting with a fully-obscuring child</title>
<link rel="author" title="L. David Baron" href="https://dbaron.org/">
<link rel="author" title="Google" href="http://www.google.com/">
<link rel="help" href="https://drafts.csswg.org/css-contain/#content-visibility">
<link rel="help" href="https://bugs.chromium.org/p/chromium/issues/detail?id=1370776">
<link rel="match" href="../../reference/ref-filled-green-100px-square.xht">
<style>

div { width: 100px; height: 100px; }

.small { height: 50px; }

.hidden { content-visibility: hidden }

.green { background: green; }
.red { background: red; }

</style>

<p>Test passes if there is a filled green square and <strong>no red</strong>.</p>

<!--
  This example shows the bug because the child would fully obscure the
  parent if the parent were not content-visibility: hidden.

  If the child has class="small", then the bug is not present.

-->
<div class="green">
  <div class="red"></div>
</div>

<script>

document.documentElement.addEventListener("TestRendered", function(event) {
  for (let elt of document.querySelectorAll("body > div")) {
    elt.classList.add("hidden");
  }
  document.documentElement.classList.remove("reftest-wait");
});

</script>