I am using following HTML code to load ad from My server, I want to display it at center, I'm using some styles I got from Internet but nothing is working.
It is displayed at right corner , It must be responsive and at center
    <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
    <html>
    <head>
    <style type="text/css">
    html, body {
    width:100%;
    height: 100%;
    margin: 0px;
    padding: 0px;
// some code I got to center that content
    max-width: 100%;
    max-height: 100%;
    margin: auto;
    overflow: auto;
    position: fixed;
    margin-left: auto; margin-right: auto;
    }
    </style>
    </head>
    <body>
<!-- this script loads the ad -->
    <script type='text/javascript'>
    var age = "23";
    var gender="male";
    //var location1="testifying";
       var m3_u = (location.protocol=='https:'?'https://openxtest.wfihotspotnet.in/delivery/ajs.php':'http://openxtest.wfihotspotnet.in/delivery/ajs.php');
       var m3_r = Math.floor(Math.random()*99999999999);
       if (!document.MAX_used) document.MAX_used = ',';
       document.write ("<scr"+"ipt type='text/javascript' src='"+m3_u);
       document.write ("?zoneid=6");
       document.write ("&TarGender=");
       document.write ('&cb=' + m3_r);
       if (document.MAX_used != ',') document.write ("&exclude=" + document.MAX_used);
       document.write (document.charset ? '&charset='+document.charset : (document.characterSet ? '&charset='+document.characterSet : ''));
       document.write ("&loc=" + escape(window.location));
       if (document.referrer) document.write ("&referer=" + escape(document.referrer));
       if (document.context) document.write ("&context=" + escape(document.context));
       if (document.mmm_fo) document.write ("&mmm_fo=1");
       document.write ("'><\/scr"+"ipt>");
    </script>
    </body>
    </html>
Whats is wrong in this code, Thanks in advance
 
    