[CraigBuchek]

Variable/constant names aren't just used to keep DRY, and to encapsulate functionality. They're also used to express intent. To me, this is one of the most important reasons for using variables, instead of "magic numbers".

[tptacek]

Stylesheet variables are a very good idea, but just as a reminder, the validity of the idea isn't really the question here, even if Bos makes some good points (particularly regarding the fact that the extension will break a whole constellation of authorship tools).

The question isn't whether to implement higher-level stylesheets. It's where to implement them.