Centerbox and right sidebox has kind of a large gap

I am interested in trying to reduce the gap between the centerbox and the right sidebox or at least center the content so that it doesn't look uneven.

It is probably difficult to understand the question without seeing it so below is the direct link to the page. I have some tabs setup but I have pinpointed the issue to the zencart template and not any of the coding for the tabs. Any suggestions on how to close the gap or center it so it looks a little more even would be greatly appreciated.

https://www.stxm + illing.com/index.php?main_page=page_4 (remove the + from the link)