Feature Request: Add ability to define custom layer colors

[maxrzaw]

It would be nice to be able to define custom colors for each layer instead of the currently hard coded cycle.

I think this could be achieved with 64 constants for full customization of all 32 layers, but all I really care about are the first 6 or so layers.

I am pretty sure that this will require modifying this function in the underlying zmk fork.

Thanks for making great keyboards!

[ReFil]

This can probably be made available to users when we refactor into a module (see #759 )