Make a better way of selecting colors for a given `PuzzleGroup`

[jaohara]

Should I only select one color? Should I hardcode the colors and also have them in Firebase?

I think there's a better way, here - is there a way of searching for a color that is both dark and saturated? One where white text overlaid would have the best contrast, but it would still have enough going on to be visually interesting. This color could be pulled and then just lightened or darkened for the second gradient color stop?