backdrop-filter-isolation-fixed.html

<!DOCTYPE html>
<meta charset="utf-8">
<title>backdrop-filter: fixed position should not cause a backdrop root.</title>
<link rel="author" href="mailto:[email protected]">
<link rel="help" href="https://drafts.fxtf.org/filter-effects-2/#BackdropFilterProperty">
<link rel="match"  href="backdrop-filter-non-isolation-ref.html">

<div>
  <p>Expected: Two green boxes overlapped by a yellow box. The overlapped region<br>
  of BOTH green boxes should be inverted (pink).</p>
</div>
<div class="box outside">
  <div class="box stacking-context">
    <div class="box filter">
    </div>
  </div>
</div>

<style>
.box {
  position: absolute;
  width: 100px;
  height: 100px;
  background: green;
}
.outside {
  top: 110px;
  left: 10px;
}
.stacking-context {
  position: fixed;
  top: 110px;
  left: 130px;
}
.filter {
  width: 160px;
  height: 160px;
  top: 30px;
  left: -90px;
  backdrop-filter: invert(1);
  background: #ff08;
}
</style>

chromium/third_party/blink/web_tests/external/wpt/css/filter-effects/backdrop-filter-isolation-fixed.html