chromium/third_party/blink/web_tests/external/wpt/css/css-fonts/size-adjust-tentative-ref.html

<!DOCTYPE html>
<title>Tests the size-adjust descriptor of @font-face</title>

<style>
@font-face {
  font-family: custom-font;
  src: local(Ahem), url(/fonts/Ahem.ttf);
  unicode-range: U+20, U+30-39; /* Digits and space */
}

.target {
  font-size: 10px;
  font-family: custom-font, sans-serif;
}

.unaffected {
  font-size: 20px;
}

.square {
  display: inline-block;
  vertical-align: bottom;
  background-color: black;
  width: var(--l);
  height: var(--l);
}
</style>

<p>size-adjust should scale ascent and descent metrics in 'line-height: normal'.</p>
<div class="target">
  123<br>
  123<br>
  123
</div>

<p>In a text node with multiple fonts, size-adjust should only scale characters in the modified font. In the test case below, digits should be scaled, but not letters.</p>
<div class="target" style="height: 30px">
  123<span class="unaffected">xxx</span>
</div>

<p>In nested elements, size-adjust should be applied to each text segment independently. Both elements below should be scaled to 50% of their original sizes, respectively.</p>
<div class="target">
  123
  <div style="font-size: 200%">
    456
  </div>
</div>

<p>The computed 'font-size' value (i.e., 'em') should not be affected. But 'ex' should be scaled since it's measured from the actual glyph.</p>
<div class="target" style="font-size: 20px; line-height: 1">
  <span class="square" style="--l: 1em"></span><span class="square" style="--l: 0.5ex"></span>
</div>