css/css-text/white-space/trailing-space-position-001.html

<!DOCTYPE html>
<title>CSS Test: Positions of trailing collapsible spaces</title>
<link rel="help" href="https://drafts.csswg.org/css-text-3/#white-space-phase-2">
<link rel="author" title="Koji Ishii" href="mailto:kojii@chromium.org">
<link rel="stylesheet" type="text/css" href="/fonts/ahem.css" />
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<style>
.container > div {
  font-family: Ahem;
  font-size: 10px;
  line-height: 1;
  color: gray;
  width: 5ch;
  outline: 2px solid orange;
  margin-bottom: 6px;
  position: relative;
}
.pre-wrap {
  white-space: pre-wrap;
}
.bg { background: purple; }
.h { outline: 4px red solid; }
</style>
<body>
  <section class="container">
    <div>1234<span data-line="0" class="h"> </span>567</div>
    <div>1234 <span data-line="0" class="h"> </span>567</div>
    <div>1234567<span data-line="0" class="h"> </span>567</div>
    <div>1234567 <span data-line="0" class="h"> </span>567</div>
    <div class="pre-wrap">1234<span data-line="0" class="bg"> </span>567</div>
  </section>
<script>
for (let e of document.querySelectorAll('[data-line]')) {
  test(() => {
    let y = e.offsetTop;
    assert_equals(Math.round(y / 10), parseInt(e.dataset.line));
  });
}
</script>
</body>