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

<!DOCTYPE html>
<meta charset="utf-8">
<title>backdrop-filter: Correctly apply reference filter</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-clip-rect-ref.html">

<div>
  <p>Expected: A green box, color-inverted inside the short, wide box with a<br>
  blue border and rounded corners, and not color-inverted anywhere else. In<br>
  particular, there should be no color inversion inside the tall, narrow box,<br>
  or anywhere outside that.</p>
</div>
<div class="box"></div>
<div class="navbar">
  <div class="menu"></div>
  <div class="menu2"></div>
</div>

<svg xmlns="http://www.w3.org/2000/svg" version="1.1" style="display:none">
  <defs>
    <filter id="svgInvert">
      <feColorMatrix in="SourceGraphic" type="matrix" values="-1  0  0 0 1
                                                               0 -1  0 0 1
                                                               0  0 -1 0 1
                                                               0  0  0 1 0"/>
    </filter>
  </defs>
</svg>

<style>
div {
  position: absolute;
}
.box {
  width: 200px;
  height: 200px;
  top: 100px;
  left: 100px;
  background: green;
}
.navbar {
  width: 300px;
  height: 50px;
  top: 150px;
  left: 50px;
  border: 2px solid blue;
  backdrop-filter: url(#svgInvert);
  border-radius: 10px 20px 30px 40px;
}
.menu {
  width: 100px;
  height: 150px;
  top: 50px;
  left: 95px;
  border: 2px solid red;
}
.menu2 {
  width: 100px;
  height: 30px;
  top: -34px;
  left: 95px;
  border: 2px solid red;
}
</style>