To use my custom TST addons you will need to copy the userChrome.css to your firefox profile, and either add the treestyletabs.css to your TST addon preferences or import the treestyletabs-\*.json preferences to your TST addon (_prefered_)
If you dislike some of my my other changes to FF (added vivaldi's folder icon, removed the superbox, cleaned up the borders, removed the titlebar) then remove everything below CUSTOM MODIFICATIONS in userChrome.css