Someone already posted styletron which to me is a lot better, but anywho the point of it is to minify your CSS a lot more. If you have something like `margin: 10px` in several different places, it will refactor it out into a new class and apply it to all of those elements. In a big project, it saves a lot of space and you end up with a pretty small CSS file.

Admittedly, I have no idea how well this performs with code splitting though. I like the fact that with code splitting, each page will just load the assets that it needs for that page to render and function.