Removing Header Padding?

Hi there, So I haven't been able to figure out what code controls the header and the padding. I want it to be 0 and have no space above the header image. I tried switching out a bunch of code but nothing seems to affect it. I saw that similar themes are able to control this through the custom CSS box and I was wondering if there was a similar solution. My website is: http://www.x-tactics.com/