I just committed the editCSS feature.
To activate it, set the perm in features admin panel; also set the group perms in tiki section.
Further css analysis tools will be easy to produce, and will probably come soon. By the way, the system for creating new css is rather special, and it's not an innocent choice.
You can only modify css files that end with your name, but can edit all others. That means a css can end with a name like boreal-mose-john-phil.
It can be very funny or very annoying, depending on how you feel. Personnally I want to see that.