OSMC Skin 4:3 aspect ratio support

Hello there!
Recently started using OSMC on my older 4:3 CRT, and would like to use the OSMC skin with it, as it looks so beautiful. I read on the wiki that it should be possible to get 4:3 by editing some skin files, but I have no idea where to find these files. Can somebody help me with this?

Thanks for the great software!