This is a very basic guide on how to change the fundamental colour scheme in HAP+ using CSS. This is far from comprehensive and only changes a few of the colours, but if you were wondering how it might get you started It will perhaps be useful to no-one else but me..
What you will need:
A logo for the Left-hand block. (i made mine 350 pixels wide - but i havent tested the impact of this in mobile view etc. Any bigger and it was only showing partially)