Thread:KylaraE/@comment-4109966-20191125183958/@comment-23771723-20191125195522

Hi! It's done with CSS, which you can view as MediaWiki:Wikia.css. The code is near the bottom, search for "Unique page backgrounds" to jump there. Note that this code is written for backgrounds that are "split" in Theme Designer, so there's separate code for the left and for the right sides; if the default background isn't split, then the code would be different. (I wrote the code, and Cryptid Coordinator did a fantastic job at creating the alternative background images.)