Fixed Navigation bar help

Hello, I wanted to have the navigation bar fixed at the top. I did it and then I realised I need the header element to be fixed as well, so that it doesn’t look like a single bar scrolling down. I put the header fixed too, but my problem is that it affects the header image as well. Is there a way to make the header img not to be affected by the header? To somehow separate the #header and #headerimg?

Here’s the blog.