[GNC] Changing colors and layout on 4.8

[AC]

Ok, finally got upgraded to 4.8, so far so good.

A couple things I want to change if at all possible:

First is the color schemes, I'd like to change the ledger to dark grays 
and also change the overall UI to have a darker color if possible.

The other thing I was hoping to do is reduce the size of the tabs.  They 
seem to be using a touchscreen sizing (large areas of empty space to 
allow for finger tapping) and I'd like to shrink that down, especially 
the register tabs (I have them set to the left and they are quite tall).

Where would I go about making these changes if possible?