Kind of random PHP question

I'm thinking about ways to modify Atahualpa to use with clients who want to be able to customize their site but in the lowest-effort way possible. I've already played with removing a bunch of the setting tabs/ options so as to only allow them to modify the things I know they'll want to mess with. Now I'm wondering what it would take to have a couple single entries for the site color scheme that would auto-populate the individual color settings.

So for example, if they are using three colors (let's say red, blue, green), they would need to select a primary color, a secondary color and an accent color. The primary color would be all headers, the secondary would be all links plus the sidebar border and the accent would be the link hover color and the sidebar backgrounds. (These are random, made up examples - that would probably be ugly). What would it take, generally speaking (but more specifically than "PHP") to make that happen on the admin side?

This is still pretty theoretical, I'm just curious. My PHP isn't amazing, but I can usually pick out solutions to specific problems in it.

Related: Might someone be willing to give me a hint as to how I could move many of the color settings to one tab and have them all use the color picker/ show the color like the link color fields do? I'm not asking you to do it for me, just give me a nudge in the right direction

Thanks & looking forward to learning/ theorizing/ discussing