My streaming markdown renderer does something like that https://github.com/day50-dev/Streamdown

You define a baseline color in HSV and then everything else is a multiplier of that

For example

[style]

HSV = [0.7, 0.5, 0.5]

Dark = { H = 1.0, S = 1.2, V = 0.25 } # Make dark elements less saturated and darker

Symbol = { H = 1.0, S = 1.8, V = 1.8 } # Make symbols more vibrant

As a result you can simply move around the HSV to your preference in the config and things don't look like garbage where you have to hand tweak every color to get something legible.

For example, this simple loop https://github.com/day50-dev/Streamdown?tab=readme-ov-file#c...

It's effectively a swatch