just-the-docs/_sass/typography.scss

h1,
.text-alpha {
  @include fs-8;
  font-weight: 300;
}

h2,
.text-beta {
  @include fs-6;
}

h3,
.text-gamma {
  @include fs-5;
}

h4,
.text-delta {
  @include fs-2;
  font-weight: 300;
  text-transform: uppercase;
  letter-spacing: 0.1em;
}

h5,
.text-epsilon {
  @include fs-3;
  color: $grey-dk-200;
}

h6,
.text-epsilon {
  @include fs-2;
  color: $grey-dk-200;
}

li {
  .highlight {
    margin-top: $sp-2;
  }
}

hr {
  height: 1px;
  padding: 0;
  margin: $sp-6 0;
  background-color: $grey-lt-100;
  border: 0;
}

.text-small {
  @include fs-2;
}