[cel1ne]

I use http://tachyons.io/ for everything and couldn't be happier. It gives you lots of singe-purpose classes that you mix and match.

And most importantly it gives you a REM-relative scale for your spaces: http://tachyons.io/docs/layout/spacing/ and for typography: http://tachyons.io/docs/typography/scale/.

So everything is responsive and I don't ever have to think about pixel-values again.

I even ported it for React Native: https://github.com/tachyons-css/react-native-style-tachyons