Sidebar width issue

Cannot seem to change the width of the sidebar. See here and you will see the MPU’s in the right hand column overlap.

I have done the obvious and changed the widths in the stylesheet but it has not changed anything.

Could this be that the white background is purely an image and that is what needs amending?

There is always an answer where wordpress is concerned, just can’t crack this one at the moment, thanks in advance to any help.