netbox/netbox/project-static/styles/custom/_code.scss

// Serialized data from change records
pre.change-data {
  border-radius: 0;
  padding: 0;

  // Display each line individually for highlighting
  > span {
    display: block;
    padding-right: $spacer;
    padding-left: $spacer;

    &.added {
      background-color: $green;
    }

    &.removed {
      background-color: $red;
    }
  }
}

// Change data diff w/added & removed data
pre.change-diff {
  border-color: transparent;

  &.change-added {
    background-color: $green;
  }

  &.change-removed {
    background-color: $red;
  }
}

// <pre> elements displayed with a border
pre.block {
  padding: $spacer;
  border: 1px solid $border-color;
  border-radius: $border-radius;
}