MyBB Community Forums

Hey guys i have come up with one new problem...today i tried to modify and make a custom theme for my forum and now it looks much better but i have come across one problem please help me with this please tell me which css code i need to edit to fix this im kinda lost and beat...
herez the error

See here
http://community.mybb.com/thread-75337.html

thanx a lot i got it fixed now...