Oh, I didn't notice they were round.

Judging by the top left corner of the first post in your screenshot, the round image isn't aligning with the header.

There are a few possible solutions to that

1. The image isn't the same height as the header image. You need to add transp. pixels above so it is the same height.
   
2. use padding-top on the image to make it fit

Also, I noticed that in your (original) version the lines underneath the title and above the comments don't go all the way across like they do in my version. So if you want that back with my code, then...

1. change in .post h2
   padding to margin of the same value
2. .comments {
   In here this is inherited from the P tag, so you will have to set padding to 0 and margin to the same as in the previous example.