Universal CSS for jquery and modifications?

[toplisek]

I have put additional CSS to standard jquery style.
Will this mix with existing classes? Should I delete those classes in universal CSS for jquery.

How is correct way to do this?

[coopster]

I'll assume you are referring to the jQuery UI. Open up the css and you'll find a link inside the comments that you can cut/paste into your browser where you can customize the style using their themeroller.