Board Thread:Support Requests - Designing Your Wikia/@comment-3219540-20150512174826/@comment-452-20150513134652

Seconded regarding the clarity of where each style comes from. If you're using a browser in which it is unclear, then you should reconsider your life choices choice of browser.

One of the reasons why it is discouraged is simply because theme designer is designed to be used to change the background, and Wikia prefers in most cases that you use the built-in features.

In fact, in many cases the use of alternate methods to achieve the same goal as a built-in feature is disallowed, such as... using JS or CSS to "protect a page" by hiding the edit button for non-sysops. The outcome is essentially the same as just using normal page protection, but the line has very clearly been drawn so that it doesn't matter that it has the same effect, you should use the built-in feature.

This is probably why 184.69.149.182 thought that it was against the TOU.

Another reason, why was recently relevant, is the "split background" introduced by the Fluid layout. It only worked if you set the background using the theme designer, and if you set the background using CSS, then it probably got covered at larger resolutions. Unless you use a tiled background, which is what I now use after I got tired of trying to get my previous background working with the fluid layout