As of yesterday, Wikia made the syntax highlighting feature go SITE WIDE. This feature causes source mode to become colored, where each bit of code is a different color. This apparently "helps you see the code", although it doesn't help me at all; but to each their own. Now, you might like it, or you might not, but it can be easily turned off by going to Special:Preferences and ticking the "Do not show syntax highlighting in Source mode" box under the Editing tab.
Here's the blog for those wondering: [1]