Board Thread:Support Requests - Designing Your Wikia/@comment-24082086-20140228052838/@comment-168424-20140228061409

This can be done, but it means overriding alot of CSS classes. You may want to get the Firebug addon for Firefox (if you used Firefox) or the equivalent for your browser and search for all the classes that have button in the name and add rounded corners or a gradient. The problem is these buttons use different classes in different places, so it will take alot of work. Maybe someone reading this thread has done something similar on their wiki so you can just grab their CSS and modify it.

You should also consider contacting the Community Development Team for help. They may have already done something like this for some other wiki and can give you a chunk of CSS to work with.