You need to recompile stylesheet using Sass. See this post: http://www.artodia.com/threads/change-b ... #post-8463
Unfortunately that's the only way to do that for now. There are no decent parsers for Sass written in PHP, so to compile stylesheet you must install Sass on your computer and run it from command line. Good news is it takes like 1 minute to install everything if you have Mac. On Windows it might take a lot longer.