Changing Genesis Main Content Padding

Hello Friends,
i know this have been asked, or it seems easy, but i am new to genesis and using Genesis Mag Pro and thus have this problem.
I want to increase my main content area by decreasing the padding in between the two sidebars, i have in my site. I have tried to it with making changes to style.css, but have not been able to achieve what i wanted.
website is https://www.pccracker.com/WordPress/ which is a new blank page on which i am trying to make changes.
I know basic css, so i will not have any problem in understanding your proposed solution.