[heycam]

As pornel pointed out, CSS Variables are really custom properties that cascade and inherit just like regular properties. Since "$" is used by CSS preprocessors for variables that work in a different way, I think Tab felt that it would cause too much confusion to use the same symbol. The set of remaining ASCII non-alphabetic characters that CSS doesn't use is pretty small too; perhaps "$" is slated for use by some other feature.

There's also a desire in the WG to have a consistent naming scheme for custom CSS things, including custom media queries, custom pseudo-classes to use in selectors, etc. "--" is something that doesn't scream "variables" and so would be usable for those other things.

[parallelist]

> Since "$" is used by CSS preprocessors for variables that work in a different way

A complete perversion of priorities. CSS generator languages change and go in and out of fashion all the time but CSS itself will be around for a very long time. They should make the best decision for the future of CSS. Generator languages are inevitably going to need to change to take advantage of any new feature anyway.

[kijin]

I agree. The people who develop web standards nowadays seem to have a curious aversion to existing implementations. First they rejected WebSQL because it was based on SQLite. And now they can't use the dollar sign because it's used in Sass? Is this just a bad case of NIH syndrome, or is there something more?