I'm far from being even "above average" at CSS, but this approach (as a long time developer, mostly in OO) has made the most sense to me. Little bundles of things in their own contexts that apply to a limited area. I can re-use names as they are appropriate for their contexts and not worry about cross contamination.

But, other people do things differently so maybe it's not the best approach for them; but for my limited needs and experience, it's been fine, if not great.