Dark theme and personalized fonts

[cicciobello]

I'm not a programmer. I have only a little personalize "style_sheet.qss" with Copy/Paste and modify numbers. My "style_sheet_win.qss" is empty.

Now, I want to try Dark theme, but my file "style_sheet.qss" don't work anymore.
How can I modify some MP fonts? Which QSS file do I use?
How can I read more about these "QSS" files?

My goal is to change only some colors (a little brighter) and some fonts (a little big and monospaced).

[xnview]

Dark theme doesn't use .qss, you can't customize it