Tips for Writing CSS
Position Is Everything - How To write Efficient CSS
One of the touted benefits of CSS is that it reduces total page weight, and thus download time, both at first page load, and even more on subsequent loads due to style sheet caching. This is true, but often a sizable fraction of the first load savings is lost because of highly redundant CSS code.
(via xBlog)
mezzoblue - Redundancy vs. Dependency
CSS forces you to make a choice in your coding techniques, a choice that becomes more obvious the larger a site grows. As the amount of variance between different templates increases, you can go in one of two directions: you can either code for redundancy, or code for dependency.