[Css Variables] Variable Declaration Blocks

Hello all,

I Just subscribed to the mailing list. I am interested in the recent  
proposals for variable declaration and variable blocks as I have been  
working on a css preprocessor which adds (ao) these features to css.

Could someone summarize the current state of the proposal, or direct  
me to a post with an overview?
What syntax does webkit currently implement, and what are the  
different syntaxes still under discussion?

Thanks in advance,
-Alwin