Background Issues

You have your background css code set to repeat-x left bottom, so it lines up with the bottom of the browser. It is only having a problem on your post page because your post page is longer than your current index page. The longer a page gets, the more space you will see up top. For resolutions that are larger, there is going to be even more space at the top. The only way to fix it and keep the image you have is to make the background bigger (which I would NOT recommend because it already takes far too much time to load on high speed internet). You could set the background color to white, but your image will still cut off up top.