Let's face it. CSS is dumb. There is no such thing as a DRY CSS file and stylesheets are often the biggest blemish in an otherwise beautifully coded app. Sass is the future of stylesheets. Rails 3.1 includes it by default and the W3C is adding concepts from Sass to CSS itself.
Many CSS Frameworks have been introduced in recent years, some are now quite popular. The advantages (fast development, cross-browser compatibility, table-less design, etc.) are exciting, but the disadvantages (bloat, lack of flexibility, lack of what is already available in css) are equally…