[Question] How can I disable nocsd for one application if I have it enabled globally?

[ghost]

I have enabled it globally,but I don't want to use it for firefox,so how can I disable it for that?
I tried starting firefox with "GTK_CSD=1 LD_PRELOAD=0 firefox",but that still doesn't work,it looks like this:

[SkyyySi]

If this issue is speciffic to firefox: Right click an empty spot in the tabbar, click customize and at the bottom left check the titlebar option.