Should work just fine. Copy down to your workstation, use any editor you want, then copy back to the server and overwrite.
that works ONE time. but if you then edit that particular style, it will grab the DB stuff and all your nice text edits are gonzo. that's why you'll see what looks like multiple copies of xxxx.css in your styles folder..
the key is to use import or copy from existing to get a new db entry for the style then use the style editor in the control panel. when you 'save', the db entry is updated and a new xxxx.css file is created to be included by your forum.
ftp'ing doesn't cut it.
