Hi, I showed the app to my gf for some stretching exercises suggestions. During my showcase of the app, she thought the exercises color on the calendar looked weird with the app theme that I chose. And indeed I agreed it looks somewhat weird.
Why ? The app theme choice is restricted while workout colors are from a color picker which gives in my opinion too much liberty. At lest the end result is cheap if you don't take time custom picking the neat perfect color that matches your current UI color choice.
I'd like to suggest creating custom palettes that encapsulate both. For example, a pastelle color palette. And the UI and workout parts would be selected from a pre-defined list.
Another one would be retro, vaporware, forest, modern...
The idea would be to somewhat restrict the user choice and yet make him feel like the app is more polished with a simple color set that matches.
The user could still define or change each one independently like this is the case today of course.
I provided a screenshot of what made my gf suggest it, and how it is implemented in an app called Daylio which I think looks great with a simple customization scheme.

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