[Timmy_C]

This is a killer HTML/CSS boilerplate. It's clean and simple and does just enough to get a responsive layout up-and-running.

[Kallikrates]

I heavily prefer it for simple sites. Once you start needing all the bells and whistles, you can look elsewhere. Right tool etc... Don't need twitter bootstrap for every blog or repo site out there.

[shredfvz]

You might also consider Stylus Skeleton: https://github.com/archware/stylus-skeleton

I ported Skeleton CSS to Stylus one day using ideas from Stylus Boilerplate.