no problem. What you have now looks good, so you may not need it unless/until you do a redesign.

They basically have a set of predefined CSS classes for layouts to give you a starting point. Blueprint and some of the others also have a default set of styles predefined, and you can find several examples of people who have added to them. It basically gave me a good starting point instead of having to hack up my own CSS from the start.

They also claim to help resolve several of the CSS differences between browsers, but I haven't tested that first hand yet.