Can't open common5 on Brawl Box

[marroking]

Hey everyone I'm new at this and I cant seem to edit my CSS. In Brawlbox i tried looking at the guides but i couldn't seem to find any answers.  :'(
If there is another way to edit CSS let me know but so far I get hit with this..

[windhunter7]

If you can't open it, it's bugged and you should just get a fresh one from the resources. If you can't modify it, I dunno.