Changing width of left colum in forums

[Profesie]

I've looked around about changing the avatar size and I finally got it where I want it but adding in some code to a css. However it's a bit to big for the left grey column when reading the forums.

http://puu.sh/h0Bhz/be8eb0d1e7.png

The picture... how to I make the left column wider to support the size avatar that I want? Thank you!