A firefox theme
This theme uses colors from: design-tokens
This theme is basically a fork of this theme, i have permission of the original author to continue this theme.
I recommend to take a look on here on how to use css themes for firefox.
For tabs i'd recommend an addon like Tab Center Reborn
If you have trouble with the colors you can install Firefox Color and manually import the colors in the Custom colors tab, you can find the colors inside the colors folder.