body background moves left on single post pages

I need some CSS/design help here. I’m completely done editing my template, except now my single post pages have a background image between the header and footer that is shifted to the left about 20px. You can see the effect here if you click on a post title. I have centered my page with auto margins rather than using set left margins.

https://www.jonvandalen.com/newblog

The single.php file I have edited to use narrowcolumn, the same as my index page, so it can not be an issue with narrowcolumn vs widecolumn. I also tried replacing single.php with another php file like page.php and that did not fix the problem either.