Hi guys, Joshcat here.
Now, this probably won't concern you if you aren't either a bureaucrat or admin, but alas, I spend tons of work into this. After ~8 hours of trying to make it work, I've finally done it. I have finally added some MediaWiki:Common.css! Well, the common.css didn't work because this Wiki is old and I had to transfer it to MediaWiki:Wikia.css , but that's besides the point. It still awesome nonetheless (well, in my opinion)!
But what does this CSS code do, you might ask? Well, Bureaucrats and Admins now have their own respective colour when their name appears in the "Recent Wiki Activity" tab, Message Walls, and more, along with a special icon! For Bureaucrats it's a Rainbow Crystal Block (along with their names being in a magenta colour), and for Admins it's an Emerald Block (along with their names being in a light green colour).
I might add more colours for other Ranks along with a different icon, maybe a Crystal Block or Ruby, if I know how to.
Anyways, that's all for now. Happy editing!
PS: HUGEEEEE thanks to Andrey Andrey, he helped me work out some problems I was having.
UPDATE: Content Moderators now have a Topaz Block beside their name along with a dark orange colour.