Well you can do this but you will need to use a custom class as well as the css...
it will also have to address a few things...
like your sections that have really long titles...you would need a way for a user per page load to be able to dismiss that image laid out on top as there is no way to always put it between due to size constraints.
I did this live on your page with firebug real quick ...I didn't add an image because that is just secondary to the issue and I could just as easily removed the background color and used an image. We are looking for position first then beauty.
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The real issue is a consistent placement regardless of the title length. If you do manage to accomplish this with css only you will run into problems in the long run.
I see you said you have things sorted out almost so if you can manage by yourself good for you but if you want some help let me know.