Unremify all the things

It's been a week since we use px_to_rem to remify our code instead of Sass, and it seems to work very well!

This means we can get rid of ~2800 lines of code :) And say goodbye to:

> remify

In pull requests!

![ ](http://media.giphy.com/media/UFcBDeIC1lPva/giphy.gif)