One of the reasons I've switched to a microframework (Milligram) is that the source is extremely easy to read and understand.
Compare mini.css (https://github.com/Chalarangelo/mini.css/blob/master/src/min...) to Milligram (https://github.com/milligram/milligram/blob/master/src/_Form...).
Unless you're planning on inlining your CSS in the head tag, IMO the network difference between 7kb and 20kb of CSS is just splitting hairs. I've gotten far more out of optimizing my CSS for programmer understanding than network size (though the two tend to be correlated!).