Petit Mondrian

If you put a lot of information into your sidebar using the Petit Mondrian theme, it will become very tall.  

Under normal circumstances, the theme will scale to meet these demands, but sometimes you’ll end up with a single post and a bunch of sidebar-colored space underneath it.

To avoid this problem, increase the Minimum Index Page Height beyond 1200px. This will shove your footer a bit further down the page, but at least the colors will be in the right place.