Add SASS org

Split this off into a separate PR so you can play with it before deciding to merge or not. I'm trying to keep my fork as close to yours as possible, and I think organizing the SASS this way makes the CSS more modular and easier to figure out what you want to edit at a given time. Since this is your fork, it's up to you if this is what you want to do, but I do think you should reconsider.