OK, this is not by me, and all credit goes to this creator: https://www.deviantart.com/rhubarb-leaf/gallery/ I am personally running the Snow Leopard theme on 10.9.5, and it looks so good. And there are many others, like Tiger, and Pinstriped (Jaguar/Puma) style. And there are themes for those who are using Mountain Lion, too. If we had this level of customization on most recent versions...it would be beyond amazing. So, enjoy. Here is the Snow Leopard theme I am running. Look at buttons, sliders... those are all from SL, running on Mavericks like a charm. The only downside is that Aqua sliders do not have inactive state, they do not turn gray when window is inactive. Thank you, rhubarb_leaf, if you are watching this thread.