chore(styles): refactoring the Sass per scss-lint feedback

Yeah, this got bigger than I thought.
Found a nice scss linter, [scss-lint](https://github.com/causes/scss-lint), but it's in Ruby (sadface), so I'll leave it as something we run manually from our dev machines rather than something we install Ruby for on the Travis machines for this one task.
> Or I can delete the // backgound-image: since it is commented out anyways.

Let's do that