Sidebar lenght

Hi,
I have a lttle problem, maybe somenone can help me.

I set the theme for side and optimized random things. All works finde, except of one (simple?) thing:

the Sidebar respectively the room unter the sidebar. As soon as the content goes longer as the high of the sidebar(-widgets), there is a white box under the sidebar as you can see on the following link:

http://www.energiewohlbefinden.de/spirituelle-beratung-und-begleitung/

I tried random things in the css, but all that changes is the position of the text in the content-area, not the width of the content-area.

I just want to remove this little white space under the sidebar, which you can see, if you’re following the link…but I can’t find the solution for this problem.

So maybe someone can help me here?