Sidebar moves CSS help?

Hi
I wonder if somebody would be kind enough to advice me on a solution. I am assuming it’s a CSS issue, but not 100% sure.

I installed another theme to view it and when I swapped back to the original one the right hand side bar has shifted out of place, moving far right.

I imagine (hope!) there is a simple solution.

http://www.sbtdesign.co.uk

Thank you in advance if anybody can help. 🙂

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style.css below.

[CSS code moderated – a link to your site is enough to access the styles]