Carolina's Purple is a Firefox theme that provides balanced purple colours that are light, but work seamlessly with dark mode to reduce eye strain.
A matching version is available for Thunderbird, so your browser and your mail client use the same palette.
Tabs, toolbars, the address bar, the sidebar, and menus all follow the same palette, so the browser stays coherent rather than purple in some places and default grey in others.
Colour palette If you want to match your OS or other apps, here are the exact values used in this theme:
