I can only see issues with the background on your site. This is already resolved in the next release. VaultWiki wasn't applying the correct background swatch and it wasn't being used on all the appropriate elements. The next release also has fixed many issues with conflicting CSS rules (like the headings being huge).
I cannot find an example of a button that's styled wrong on your site, but can see how this might happen. VaultWiki had its own Style Property for buttons. Originally when we made the Style Properties, it was not possible to modify XenForo's button properties on a per-state basis, so we continued to have a separate wiki button property. These should be simple enough to modify after installing a custom style anyway, but we can remove most of them now that there are stock properties to handle it. This is potentially a big change, so I'm not sure if it will make it in the next release, which is already packaged.