Hey, not trying to be a jerk here, but I am an experienced web developer who loves Compass and CoffeeScript and spends hours in dev tools daily, so I feel like I should understand your comment, but I simply cannot understand what you are asking. At all. Consider re-phrasing?

Maybe he means writing css in PHP and serving it as text/css.

That does give you pretty good flexibility.. you have to pay a little more attention to caching compared to static (/compiled) .css files though.

Oh sorry, I mean why not do the server side work with PHP or whatever on the back end, or javascript on the front end?

By breaking existing tools I mean Firebug or whatever else is viewing the compiled styles.