Forum Logo border removal

[محروم.كوم]

Hey,

I wanted to center my forum logo (banner) rather than it be to the left side.
I've looked around and found a small bit of code I can insert into the additional.css which has done the trick. However, I have a small thin white line that goes around the banner that I want to remove.

Code:
.doc_header {text-align: center; }
.logo-image {clear:both; float:none;}

Can anyone please advise where I can find this border to remove it. __DEFINE_LIKE_SHARE__