gecko-dev/layout/reftests/text/letter-spacing-nolig-2.html

<style>
@font-face {
  font-family: libertine;
  src: url(../fonts/LinLibertine_Re-4.7.5.woff);
}
.a {
  font: 32px/2 libertine;
}
.b {
  font: 32px/2 libertine;
  letter-spacing: 1em;
}
</style>

<div class="a">office

<div class="b">office