how to close the gap between the forums

[gbox master]

i have a small gap between the forums and i am searching for the setting
there must be a template where i can edit this i hope
maybe some one can direct me in a direction for this ?

see the screenshot and you will see the gap between the forums
there is a red line at the top midle and on the right and left
i would really like then to be in one line
and also close all the gaps between the rest of the forums