That's a +1 from me, I'd love an open-source version for self-hosting. I'd additionally be happy to pay for the "licence to self host" or something silly like that as long as I can see the code somehow (which is a big deal for me).
This or git clone + open source is pretty critical. I want to recommend this to my company, but I can't rely on the longevity of a fresh-out-the-gate startup for storing crucial enterprise knowledge.
We'll make the background better, and will support custom theme(or custom CSS) in the future.