chromium/third_party/blink/web_tests/external/wpt/css/css-ruby/rt-display-blockified.html

<!DOCTYPE html>
<meta charset="UTF-8">
<title>Blockifying 'display: ruby-text' loses ruby-text functionality</title>
<link rel="help" href="https://drafts.csswg.org/css-ruby-1/#block-ruby">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>

<style>
ruby {
  font-size: 60px;
  line-height: 1;
}

rt.abspos {
  position: absolute;
  font-size: inherit;
  line-height: 1;
}

rt.float {
  float: left;
  font-size: inherit;
  line-height: 1;
}
</style>

<p><ruby><span id="base">base1</span> <rt class="abspos">abspos</rt>base2 <rt class="float">float</rt></ruby></p>

<script>
test(() => {
  const base = document.querySelector('#base').getBoundingClientRect();
  const rt = document.querySelector('.abspos').getBoundingClientRect();
  assert_greater_than_equal(rt.y, base.y);
}, 'position:absolute should not work as ruby-text');

test(() => {
  const base = document.querySelector('#base').getBoundingClientRect();
  const rt = document.querySelector('.float').getBoundingClientRect();
  assert_greater_than_equal(rt.y, base.y);
}, 'float:left should not work as ruby-text');
</script>