css/css-values/ex-unit-001.html

<!DOCTYPE html>
<meta charset="utf-8">
<title>CSS Values and Units Test: ex unit computation and dependencies</title>
<link rel="author" title="Emilio Cobos Álvarez" href="mailto:emilio@crisal.io">
<link rel="author" title="Mozilla" href="https://mozilla.org">
<link rel="help" href="https://drafts.csswg.org/css-values/#font-relative-lengths">
<link rel="help" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1529537">
<link rel="match" href="reference/ex-unit-001-ref.html">
<meta name="flags" content="ahem">
<style>
  @font-face {
    font-family: foo;
    src: url('/fonts/Ahem.ttf');
  }

  @font-face {
    font-family: foo;
    font-weight: 900;
    /* A font with significantly different ex-height metric than Aham. */
    src: url('/fonts/noto/noto-sans-v8-latin-regular.woff');
  }

  div {
    font-family: foo, sans-serif;
    width: 10ex;
    height: 20px;
    background: blue;
    margin: 20px;
    font-size: 20px;
  }
</style>
<p>All lines except the first should be the same length</p>
<div></div>
<div style="font-weight: 900"></div>
<div style="font-weight: 900; width: 10ex;"></div>
<section style="font-weight: 900"><div></div></section>