Board Thread:Support Requests - Designing Your Wiki/@comment-40133711-20200724164535/@comment-39490270-20200725175953

Alternative to the option above, the FANDOM has a class on the body tag that already lets you do what you're intend. If you use inspect mode, there will probably be something like class = "[...] page-[PageName] [...]" on, and you can use it in CSS with something like this:

.page-HappyBoy .[AnyClass] { [Antyhing] }