Board Thread:JS and CSS Support/@comment-29874790-20190212005529

Before I start, note that I do not have much experience with HTML or CSS editing. I have been trying to add a parallax effect to my Fandom using CSS only (because JS is slow with this), but when I add the code to the Common.css page, the webpage looks like the image below. I have reverted the edits and the code is now here.



Digging a little deeper, it seems to be that .background-dynamic.skin-oasis is somehow related to .WikiaSiteWrapper, causing .WikiaSiteWrapper to be enlarged when it should not be. What can I do to avoid this? Are there any example websites that I can model my CSS off of? 