RandomBackground

RandomBackground set a background from a defined list randomly when you re-load (or load) a page on the wiki.

Usage
Add the script to your w:Special:MyPage/global.js (if you want a random background on all Wikia-hosted wikis) or Special:MyPage/wikia.js (for a specific wiki). Also, you can add this to MediaWiki:Wikia.js (for site-wide):

Configuration
This script needs a list of backgrounds (url) to set in your wiki. For this, you just must declare a list before of script import. You can also enable night mode and day mode.

Backgrounds configuration
By default, backgrounds are show with a default code CSS, if you want configure this there are several extra options: Here's a example: