backdrop-filter-backdrop-root-opacity.html

<!DOCTYPE html>
<meta charset="utf-8">
<title>backdrop-filter: The backdrop root concept</title>
<link rel="author" href="mailto:[email protected]">
<link rel="help" href="https://drafts.fxtf.org/filter-effects-2/#BackdropRoot">
<link rel=stylesheet  href="resources/backdrop-filter-backdrop-root.css">
<link rel="match"  href="backdrop-filter-backdrop-root-opacity-ref.html">
<meta name="fuzzy" content="maxDifference=0-5;totalPixels=0-500">

<!-- A Backdrop Root is formed, anywhere in the document, by:
     - An element with an opacity value less than 1.
     - An element with a will-change value specifying any property that would create a Backdrop Root on non-initial value. -->
<div class=container>
  <div class=testcase>
    <div style="opacity: 0.9;"><div></div></div>
  </div>
  <div class=testcase>
    <div style="will-change:opacity;"><div></div></div>
  </div>
</div>

chromium/third_party/blink/web_tests/external/wpt/css/filter-effects/backdrop-filter-backdrop-root-opacity.html