I recall someone earlier describing it as the preferred choice for those who want to go a few extra steps to retrofitting the framework to their own liking.
Looking back, I actually can't think of another reason why I chose Bootstrap over Foundation.
Would appreciate suggestions, alternatives.
If not, it's HTML/CSS that you have to learn and then you'll find Bootstrap an good resource.
Download it here:
It's not nearly as complex as Bootstrap which is great when you want create some pages quickly and use your own styles.
Skeleton, unlike all the other things I've seen mentioned, has almost no overhead, and pretty much stays out of your way. It's got sensible defaults, isn't as recognizable as bootstrap, and doesn't have any cruft.
The biggest knock on it is that it doesn't have enough widgets, but I for one don't want them. I just want a responsive grid framework that looks decent out of the box. If you're like-minded, Skeleton is a treasure.