VitaliyV

UserChromeFiles

For use in Firefox ^Desktop
and Thunderbird ^Desktop

UserChromeFiles - Scripts/styles loader extends Firefox and Thunderbird capabilities with the autoconfig function.

CustomScripts

FullTheme

Webextensions

For use in Firefox ^Desktop

Experiments and Themes

For use in Developer Edition ^Desktop (recommended)
or Extended Support Release ^Desktop (recommended)
or Nightly ^Desktop