Do you mean the WDS-buttons, like this one?
If that's what you meant, the best thing you can do is add this script in your wiki's CSS.
All that really did was flatten them and make all the letters capital. Better than before, but I wanted something like the button on the right:
Example of button with current CSS: http://pufflescp.wikia.com/wiki/User:Batreeq
Source:
I don't really know how to complete replace the old buttons with the newer ones. If anything, you can try increase the padding, but not that when clicking on the padding area, the button won't work.