Admin Forum:Changing an entire Wiki's font colour

OK, so I'm currently working on this wiki: http://hellboy.wikia.com/wiki/Hellboy_Wiki

Am I right in thinking that if I want to make changes to the font colour for the entire Wiki I should edit this page? http://hellboy.wikia.com/wiki/MediaWiki:Common.css

Basically I need a line of code that will change the font colour of the entire wiki's headings and body text. So far nothing I've tried has worked. Sir Edward Grey 08:08, July 11, 2012 (UTC)