Board Thread:Support Requests - Designing Your Wiki/@comment-26868869-20170621033253/@comment-31420862-20170621050145

CSS (and JS) customization of both new local navigation and article header is a violation of customization policy. Hence, while it is indeed possible to change the header font style, it disallowed to be implemented site-wide - the user who put it on Mugen Wiki perhaps just is not aware of it. You could, however, change the header font style for yourself through personal CSS, if you want. Mugen Wiki is using the following CSS for it: