Layout RATIO: sidebar behind menu

It’s hard to explain but this is what happens in the RATIO (@henkvrieselaar) if I put the Facebooklink in the sidebar.
The strange thing is that it shows correctly on my iMac and iPad in Firefox but on my husbands Imac in Firefox (and Chrome) it looks like this:

What can I do to fix this?

Hi Totia,

The sidebar is at the left side with this theme, so below the banner image. Not below the menu. The ExtraContent1 area is below the menu, you can put the facebook icon or whatever here, see my example page:
I hope this helps,