chromium/third_party/blink/web_tests/fast/css/font-size-adjust-system-fallback.html

<!DOCTYPE html>
<style>
@font-face {
  font-family: 'primary-font-ahem-ex-500';
  src: url('../../resources/ahem-ex-500.otf');
}
.adjusted {
  /* Scale up 200% since the Ahem ex 500 font has an aspect ratio of 0.5
     of x-height to size. */
  font-size-adjust: 1.0;
}
.test {
  font-family: 'primary-font-ahem-ex-500';
  font-size: 100px;
  color: green;
  height: 200px;
  margin-bottom: 24px;
}
.tall-inline-block {
  display: inline-block;
  height: 50px;
}
</style>
<body>
  <!--
    The glyph 'A' cannot be rendered by the primary font, so it individually
    falls back to the system fallback font. There are two glyphs of 'A' below.
    The left glyph is not adjusted, and the right one is adjusted. The right
    glyph should be bigger than the left one.
  -->
  <div class="test">
    <!--
      We are inserting a tall inline-block here to make the position of
      the baseline independent of the adjusted glyph since on the expected result
      we don't use font-size-adjust but font-size.
    -->
    A<span class="adjusted">A<span class="tall-inline-block"></span></span>
  </div>
</body>