Its actually in your forumbits.css
The problem you have is the parts you want to change colour dont actually exist as a block for you to change.
They are all layered ontop of forumrow_background
Let me show you in a 3D & 2D perspective.
This is the outcome I came out with. Notice how I managed to cover the middle and the top but the bottom bit isnt there to change, even the very top is missing at least a pixel length in colour
Put a ticket in and ask over at members on vb.com!