I don't think “colorways” is a particularly demanding experiment as far as Firefox is concerned. Firefox has a built-in theming system, they just created a few

I don't think “colorways” is a particularly demanding experiment as far as Firefox is concerned. Firefox has a built-in theming system, they just created a few more built-in themes that are only available for a limited time. I could probably have created “colorways” in <1 week despite not knowing anything about browser themes/extensions.