UPDATE - 2021-08-19 - Version 1.5: changed the tab_background_text color slightly so that it once again triggers the dark context and system menus in the new UI.
UPDATE - 2021-07-13 - Version 1.4: Added popup_border color to remove the light-gray border on some popups and menus that were added in Firefox 90.0
UPDATE - 2021-07-05 - Version 1.3.1: Tweaked tab_line color. This time it actually does highlight the current tab better than before.
UPDATE 2021-06-19: Tweaked the purple again... hopefully this one is slightly better..
UPDATE 2021-06-16: I am aware that the purple in this theme is very difficult to see on most displays against the dark background. I am in the process of trying to tweak it without losing the purple color.
If you would prefer the previous version(s), please see
https://addons.mozilla.org/en-US/firefox/addon/zorz-dark-violet/versions/ 
