Need postbit legacy help

[Emzak]

Hi. I am running my forum on vB 3.5.8 at a fixed width (800 pixels).

I just switched to postbit legacy and am having a problem with my columns when reading PMs--the message box stretches to the right and breaks out past the border (screenshot attached).

I notice that this forum is fixed width but yet your PM templates don't have the same problem as mine. How do you do it???

1) Is there any way to fix this, say, by editing a template? If so, which one and how do I do it?

2) If it can't be fixed by editing a template, is there a way to make the Control Panel (i.e. where it says "Edit Signature", "Edit Avatar", etc.) horizontal instead of vertical so that I can put it right under the navbar?

Please help.