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CSS Validator throws a parse error for selectors referring to a "not" class, e.g. .not { color: red }
Same for .only, see http://www.w3.org/mid/0AADE392-77D9-11D8-840F- 000393AF2932@idyllmtn.com
Fixed by defining class as < CLASS : "." <IDENT> > instead of asking for "." <IDENT> (and matching <MEDIARESTRICTOR> for failure)