28 Jul
2006
28 Jul
'06
3:02 p.m.
Why not? Just enter the rules that need to be changed into your new grammar and import the CSS grammar last, this way (if I understand correctly) the rules you changed are overwriting the standard CSS rules, but everything else stays the same. And, for a pretty advanced language grammar as the CSS one - do you expect any major changes coming so you really need to worry about keeping up to date?
Dan