window.onload = function() {
 var myWidth = 0, myHeight = 0;
 if( typeof( window.innerWidth ) == 'number' ) {
   //Non-IE
   myWidth = window.innerWidth;
   myHeight = window.innerHeight;
 } else if( document.documentElement && ( document.documentElement.clientWidth || document.documentElement.clientHeight ) ) {
   //IE 6+ in 'standards compliant mode'
   myWidth = document.documentElement.clientWidth;
   myHeight = document.documentElement.clientHeight;
 } else if( document.body && ( document.body.clientWidth || document.body.clientHeight ) ) {
   //IE 4 compatible
   myWidth = document.body.clientWidth;
   myHeight = document.body.clientHeight;
 }

 var fooLayer = document.getElementById('nav');
 fooLayer.style.paddingLeft = ((myWidth - 965) / 2) + "px";
}