You didn't read all my replie ;)
You're right for the body css in your stylesheet, but if you displays source of your page (use Firefox with webdevelopper plug for good check about css and more) or if ou use bad browser like IE choose in menu:
Affichage >> Source (sorry I'm french maybe for you is Displays >> Source) and you can see all the html code of your page. See the body balise: you've got an inline style like I wrote above.
And if you're not sure try this in your browser:
It's the background image you have for your body style.
But you're in hosted wordpress I don't know how this work to manage your php files and css. It's not a problem with your external stylesheet but with our php file. See your header.php if you can and the body balise in it.