I feel like an idiot.
Ok your CSS works fine straight off the download. But when I followed the steps and replaced the file the game freezes D: I opened brawlbox, downloaded a fresh common5_en.pac and "exported" the file u said and then opened your file and replaced it. Yet it freezes in-game while loading the CSS.

I think it may be the common5_en.pac when it should be plain common5.pac. But I cant seem to find a normal, fresh common5.pac ='(
You can get one here.
http://www.mediafire.com/?sharekey=bf68243dc4c908b28d78a0e5552916095d6170349cac00195be6ba49b5870170