Una cosi puo andare bene?

Codice PHP:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
    <head>
        <title>Test</title>
        <meta http-equiv="content-type" content="text/html; charset=utf-8" />
        <style type="text/css">
            #contenitore
            {
                font-size:20px;
                font-weight:bold;
                width:400px;
            }
            #box1
            {
                height:50px;
                width:200px;
                background:#ff0000;
                color:#ffffff;
                float:left;    
            }
            #box2
            {
                height:50px;
                width:200px;
                background:#cccccc;
                color:#000000;
                float:left;
            }
        </style>
    </head>
    <body>
        <div align="center">
            <div id="contenitore" align="center">
                <div id="box1">BOX1</div>
                <div id="box2">BOX2</div>
            </div>
        </div>
    </body>
</html>