Wikihack:If you prefer the old theme

The new Monaco Sapphire theme seems to have drawn no complaints so far. Some, however, might prefer the old Wikipedia-style MonoBook theme. Here is how to change back to the old theme; you will of course have to be logged in to do this. Anonymous users will get Monaco Sapphire.

After you log in, at the top right of the screen, next to your login name, you will see a button labeled MORE. Click on this tab and select "My Preferences". On that screen, select the "Skins" tab. You will find the "MonoBook" skin near the bottom; it is also identified as the "Wikipedia skin".

Bear in mind that this choice will apply to all Wikia sites that have not explicitly specified a skin, and indeed to all Wikia sites if you uncheck the box marked "Let the admins override my skin choice."