There's something not right about the way the walls meet the room that I can't put my finger on either (love the fossils, btw!).

I'd have to play around with it to find out. Maybe if you put a a very slight dark internal glow on the walls where they meet the room the transition between wall and room won't seem so severe...maybe that's it.

As I said, not sure (or perhaps I'm just imagining it).

Ravs