Header position

Hi,

I’m having trouble with my header. It’s fine on my front page, but when I click on an individual post it’s not aligned to the left anymore, instead it jumps a bit to the right.

I think this misalignment happened when I had individual posts display the sidebar, which wasn’t the default in the theme I’m using. When doing that I had to change the div ID class to ‘narrowcolumn’, for single post pages.

Does anyone know how I can fix the header? My own technical knowhow is limited, and I couldn’t find any info when searching for an answer. Thanks.

Pelle