CSS is easy, some might argue, but that "easiness" can cause messy code. This is especially true through power of preprocessors like Sass or Less where, if you aren’t careful, your CSS can become harder to deal with instead of easier. Sass? Harder? This Gist shows a great example of Sass nesting hell.
If your Sass code looks like that, you can definitely improve your code with SEM & BIO, a CSS technique I’ll introduce you to now!