How to make theme as I want to be it is

Hello everyone, first of I want to thanks EndeavourOS team, I’m having so much fun with this distro and learning quick ! It’s a real pleasure and I won’t change for a while.

As I love how configurable it is, I want to make it perfect :

as you see, I’m custumizing things (atm terminals and rofi in transparant, blue/purple), I love it. Now I want to do the same for Mozilla (no need for thunar as I think I’ll leave it for nnn sooner or later).

My question now : how to do it ? there is no config files for that and I want to make it by myself (so, no theme plusin from Firefox)

thx for the answers and sorry if it is dumb !

With difficulties.
I think it somewhat follows gtk (or was it qt?) themes but I do not know to what extent.
To fully customise it you would probably have to create your own css config (~/.mozilla/firefox/<profile>.default/chrome/userChrome.css) file but that would require hundreds of config commands with close to zero documentation.

welcome onto your purple ride :enos:

Thanks, gonna check that

@joekamprad thx doc