listen to what i did...
there is a div in your site that contain the whole site
i took it and added a id, for this example i called it bg_test --->
i went to your css file --> massage.css
<div id="bg_test" style="overflow: hidden;">
took your 'body' selector and change it to the id i've added --> #bd_test
i've deleted the background-color property so it wont color the background since you put it in the html selector.
looks like this:
background-position: center center;