mozilla-release/layout/reftests/font-inflation/intrinsic-fit-1b.html

<!DOCTYPE HTML>
<style>
@font-face { font-family: Ahem; src: url(../fonts/Ahem.ttf); }
html, body { margin: 0; padding: 0; }
body { width: 450px }
p {
  margin: 0;
  background: yellow;
  color: blue;
  width: -moz-fit-content; /* computes to 300px */
  font: 12px Ahem;
}
</style>
<!--
In a 300px container, the minimum font size at 15em per line is 20px.
This means we map 0px-30px into 20px-30px, so 12px gets mapped to 24px.
-->
<p>This is tiny bit of text.</p>