After reading, I'm still not sure why I should care.<p>I've been using "CSS variables" for years -- in <i>less</i>. If I'm modifying CSS on the fly in JS, then I don't need CSS variables; I have <i>JavaScript</i> variables.<p>Don't get me wrong: I'm not against this change. CSS has been a rather unexpressive language for some time; removing that deficiency can hardly be called a bad thing, as long as the change is consistent across browsers.<p>So, if someone wants to use this idea, well, good for them. But I've gotten along find without this feature for a long time. I don't see any particular reason to start using it now.