jQuery: addClass to HTML5 DOM
===

I am having an issue today when adding a class to an HTML5 DOM object.  Sorry if this is a newbie question. :P
Ex:
    <!DOCTYPE html>
    <html>
        <head>
            <title>stackoverflow example</title>
            <style>
            .centercontent {
                width:100%;
                max-width:1080px;
                margin:0 auto;
            }
            </style>
        </head>
        <body>
            <header>
                <!-- All direct children of BODY should be centered on the page; however, children should not be added to .centercontent -->
                <h1>Site Name</h1>
            </header>
            <section>
                <p>Hello World</p>
            </section>
            <footer>
                &copy; no one 2012
            </footer>
        </body>
        <script src="http://ajax.googleapis.com/ajax/libs/jquery/1.7.2/jquery.min.j"></script>
        <script>
            $("body > *").addClass("centercontent");
        </script>
    </html>
I believe that it is my JS; however, I have never used addClass before. Thank you all very much for your time. :)
Have a good day!