It seems to be caused by your google ads. You have an ad on the sidebar which was manually placed using a Widget and that works fine.
You also have another type which is automatically inserted by google where they shouldn’t be so it’s messing with the layout.
I suggest just using manually-placed ads similar to what’s done with the sidebar.
This is probably related: https://productforums.google.com/forum/#!topic/adsense/dQgnENvdyYY