I'm no expert on forum designs at all, so I’m only going on personal preferences here, but here is a very quick knock up in Photoshop of an idea I had floating around in my head, so apologies for the rough edges.
I made the text box the same shade of blue as you used to highlight the post and title areas. The font is just Arial and is only there because I didn’t know which font you used.
Looking to avoid what this causes and that you can just get rid of the whole speech bubble. Egg - its a change to get used to and not actually a white background
I am sitting in front of an imac with one of the brightest and colourful screens you get, its in your face and I got the file open here and looks great.
It can always change but as mentioned if you have blue for your content background you run into issues.
The actual rest of the forums is a good example. You got the same yellow on two blue's and it looks a completely different colour.
It wont be to hard for me to make an alternative theme that is just as the original for people to switch too as an alternative though.
Trying to break away from the standard forum setup. People do not because people have got too stuck into a format even though it is probably bad. I decided as a personal project to do much more with a grey theme just for the hell of it to say to people - Hey, if you actually do this - this is better, just get used to it and you will see.