Google Search page broken

[fpout]

Google Search results page is completely broken since yesterday 04-25-2013 (see attached image)

Header is broken and the top horizontal navigation menu displays fully open and vertical. It seems to be called <div id="top_nav">.
The top of the page is affected, too. Search box is fullscreen wide.

It happens on both https & http search, and disabling this filter ("Google Search: Alternate Display 12.08.19 (multi) [sd ku] (d.s)") renders the page normally.

https://encrypted.google.com/search?q=pr...8&oe=utf-8
http://www.google.com/search?q=proxomitr...8&oe=utf-8

Using Firefox 12, Sidki's set 2011-12-22rc1.