css/css-highlight-api/highlight-pseudo-from-font-computed.html

<!doctype html>
<meta charset="utf-8">
<title>CSS ::highlight Pseudo-Element Test: ::highlight selector getComputedStyle</title>
<link rel="help" href="https://drafts.csswg.org/css-highlight-api-1/">
<meta name="assert" value="Font relative units are correctly reported in getComputedStyle">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<style>
  :root {
    font-size: 16px;
  }
  div {
    margin: 40px;
    font-size: 20px;
  }
  ::highlight(highlight1) {
    text-underline-offset: 0.5em;
    text-decoration-line: underline;
    text-decoration-color: green;
    text-decoration-thickness: 0.25rem;
  }
  #h2::highlight(highlight1) {
    text-underline-offset: 1.0em;
    text-decoration-line: underline;
    text-decoration-color: blue;
    text-decoration-thickness: 0.125rem;
  }
</style>
<div id="h1">A green 10px offset underline 4px thick</div>
<div id="h2">A blue 20px offset underline 2px thick</div>
<script>
  let r1 = new Range();
  r1.setStart(h1, 0);
  r1.setEnd(h1, 1);
  let r2 = new Range();
  r2.setStart(h2, 0);
  r2.setEnd(h2, 1);
  CSS.highlights.set("highlight1", new Highlight(r1, r2));

  let highlightPseudo = "::highlight(highlight1)";
  test(() => {
    let style = getComputedStyle(document.documentElement, highlightPseudo);
    assert_equals(style.textUnderlineOffset, "8px", "Text underline offset is 8px.");
    assert_equals(style.textDecorationThickness, "4px", "Text decoration thickness is 4px.");
  }, `getComputedStyle() for root element`);

  test(() => {
    let style = getComputedStyle(h1, highlightPseudo);
    assert_equals(style.textUnderlineOffset, "10px", "Text underline offset is 10px.");
    assert_equals(style.textDecorationThickness, "4px", "Text decoration thickness is 4px.");
  }, `getComputedStyle() for root highlight applied to div`);

  test(() => {
    let style = getComputedStyle(h2, highlightPseudo);
    assert_equals(style.textUnderlineOffset, "20px", "Text underline offset is 20px.");
    assert_equals(style.textDecorationThickness, "2px", "Text decoration thickness is 2px.");
  }, `getComputedStyle() for div specific highlight`);

</script>