Applying theme to all page elements

Applying theme to all page elements

Hello,

Using this simple code:

<!DOCTYPE html>
<html>
<head>
    <title>My Page</title>
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <link rel="stylesheet" href="http://code.jquery.com/mobile/1.2.0/jquery.mobile-1.2.0.min.css" />
    <script src="http://code.jquery.com/jquery-1.8.2.min.js"></script>
    <script src="http://code.jquery.com/mobile/1.2.0/jquery.mobile-1.2.0.min.js"></script>
</head>
<body>

<div data-role="page" data-theme="b">

    <div data-role="header">
        <h1>My Title</h1>
    </div><!-- /header -->

    <div data-role="content">
        <p>Hello world</p>
    </div><!-- /content -->

    <div data-role="footer" >
        <h1>My Footer</h1>
    </div><!-- /footer -->

</div><!-- /page -->

</body>
</html>

I am trying to apply theme b to all elements on the page. Specifically the header content background should change as I change the theme, but it does not. I thought when the theme is set on data-role="page"  that all elements inherit from this. I know I can do <div data-role="header" data-theme="d">  but the question is more on inheritance. Also I do not wish to use any jQuery programming solution, just markup here.

Thanks,
Jim