Glad everyone is having fun playing with themes and styles in 1.8! Creating this category so there’s a place for discussion about this going forward.
We love when people with the inclination to tweak have some fun customizing the interface to suit your own preferences. We don’t have any imminent plans to offer color/theme customization as a feature inside Roon, but that doesn’t seem to be slowing anyone down here!
One thing for anyone who is customizing the Roon UI to note is that these changes are currently stored in a directory that’s part of our update package. That means the next time we do a release of Roon all your hard work is going to be reverted 
Make sure you back up your files in another location so they don’t get clobbered after our next update
Also, as we update Roon, the files you’re modifying may change in the future without warning. So if you are having instability or crashes, or modifications that worked in the past are no longer working, make sure to try running with stock settings.
Thanks all!