How can I make my own Theme?

Hi, I don't really post too much, but I had the idea of making my own OBS Theme.
I know most of the parts are .svg files, so there's most of it.
The thing is, what about the .obt/.ovt files? How can I make one? What are they?

It is text files, .qss (Qt Style Sheets). Extended version of the web CSS (Cascading Style Sheets). OBT/OVT is very similar files, even more extended (OBT is renamed qss, OVT is extended OBT, both extended with inheritance and variables). Use "notepad++" text editor and look how themes are made. Good examples were here: https://obsproject.com/forum/resources/categories/themes.10/ (old themes, qss files).