CSS Variables - My Positive Feedback
I really like the idea, especially for “skinnable” apps and sites. We have a few ongoing concerns here that would immediately benefit from an @variables declaration after the reset section. Coding certain large changes, of course, would also be greatly simplified. Count me as a +1.
Initially, I do wonder about rendering performance since there are issues with IE’s CSS Expressions and this seems like it could run into similar issues- then again I’m not a browser developer, so what the hell do I know? 
Since the release of CSS Level 2 Recommendation ten years ago in may 1998, the Web authors’ community has been requesting a way of defining variables in CSS. Variables allow to define stylesheet-wide values identified by a token and usable in all CSS declarations. If a value is often used in a stylesheet - a common example is the value of the color or background-color properties - it’s then easy to update the whole stylesheet statically or dynamically modifying just one variable instead of modifying all style rules applying the property/value pair. We expect CSS Variables to receive a very positive feedback from both the Web authors’ community and browser vendors.