Board Thread:Support Requests - Designing Your Wikia/@comment-25360980-20150315204446/@comment-24757753-20150320112552

You've quite a lot of selectors in your CSS, which will become confusing. Something like button, .button, .wikia-button, .wikia-menu-button, .wikia-menu-button > a:hover, .drop:hover, input[type="submit"]:not(.search-button) { border-radius: 0 !important; background-image:none !important; } seems to work to flatten and square all the buttons without changing any colours.

It also works on the dropdown menu, and continues to work after opening and closing the visual editor too. Hope this helps!