devdocs/assets/stylesheets/pages/_rfc.scss

._rfc-pre {
  font-size: .8125rem;
  min-width: 38rem;
  @extend %code;

  > h2 { @extend %block-heading; }
  > h3 { @extend %block-label, %label-blue; }
  > h4 { @extend %block-label; }
  > h3, > h4 { font-size: .875rem; }

  > h1, > h2, > h3, > h4, > h5 {
    margin: 0;
    font-family: $baseFont;
  }
}