chromium/third_party/blink/web_tests/external/wpt/css/css-highlight-api/painting/custom-highlight-painting-004.html

<!DOCTYPE html>
<meta charset="UTF-8">
<title>CSS Highlight API Test: </title>
<link rel="help" href="https://drafts.csswg.org/css-highlight-api-1/">
<link rel="match" href="custom-highlight-painting-004-ref.html">
<meta name="assert" value="When painting overlapping highlights with the same .priority, the one added last should be painted on top; and style properties not defined by the one on top (color in this case) should follow the rules of the next Highlight from top to bottom until there's one that overwrites default (or use default value otherwise).">
<meta name="fuzzy" content="0-255;0-110">
<style>
  ::highlight(foo) {
    color:blue;
    background-color:yellow;
  }
  ::highlight(bar) {
    background-color:orange;
  }
</style>
<body>Some text
<script>
  let textNode = document.body.firstChild;

  let r1 = new Range();
  r1.setStart(textNode, 0);
  r1.setEnd(textNode, 6);

  let r2 = new Range();
  r2.setStart(textNode, 3);
  r2.setEnd(textNode, 9);

  let h1 = new Highlight(r1);
  let h2 = new Highlight(r2);

  CSS.highlights.set("foo", h1);
  CSS.highlights.set("bar", h2);
</script>