overlay-transition-backdrop-entry.html

<!DOCTYPE html>
<title>CSS Position Test: overlay transition with ::backdrop during entry animation</title>
<link rel="help" href="https://drafts.csswg.org/css-position-4/#overlay">
<link rel="match" href="green-ref.html">
<link rel="author" href="mailto:[email protected]">
<style>
  body {
    background-color: green;
  }
  [popover] {
    display: block;
    visibility: hidden;
    transition-delay: 2s;
    transition-property: overlay;
    transition-duration: 2s;
    transition-behavior: allow-discrete;
  }
  [popover]::backdrop {
    background-color: blue;
  }
</style>
<div popover id="foo"></div>
<script>
  foo.offsetTop;
  foo.showPopover();
</script>

chromium/third_party/blink/web_tests/external/wpt/css/css-position/overlay/overlay-transition-backdrop-entry.html