discourse/app/assets/stylesheets/ember_cli.scss

body.requires-ember-cli {
  margin: 2rem;
  font-family: Arial, Helvetica;
  background-color: white;
}

pre {
  background-color: lightgrey;
}

pre,
code {
  padding: 0;
  margin: 0;
  padding: 0.5rem;
}