damn that how-to WAS trash. remake.
cheers
also, i urge anyone wanting to do this do read the comments in the .css files
(css comment example: /* comment, can be span in multiple lines of code */)
btw you need to restart firefox after changing anything in the .css files if that helps
open about:config
paste this in toolkit.legacyUserProfileCustomizations.stylesheets and set it to true
open about:support and open profile directory
inside the directory create a folder named chrome (the 'chrome' isn't owned by google and is actually an browser element)
go inside the chrome folder
in it copy the userChrome.css and userContent.css files, with their respective contents (you can also name the files however you like and use the @import rule from CSS
obtain an image and name it firefox.png
restart firefox
done
in this example I use those by lux
https://twitter.com/LuxxArt/status/1727019006186664230
folder example:
better examples coming in the future
this one on almost every firefox built-in page:
(sidenote: to change the padlock icon to custom thingy you need to uncomment two lines of code in the userChrome.css
why?, because i'm not sure if there are more padlock icons. for now the commented configuration is set to change for when tooltip is either:
"Verified by" or "" [on firefox about:*])
about:preferences:
i've tried a lot
and probably other things i forgot about
you can message me on my dc if you find something new/undone (there is): 42majorspellingmistakes
I'm better known as Lumi Tassu
good luck and have fun with your firefox o7