function setLeftMargin()
{
 var m = document.getElementById("media");
 var width = 990;

 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 xmax = myWidth;


 var lmarg = ( xmax - width ) / 2;
 if (lmarg < 0)
 {
  lmarg = 0;
 }

 m.style.width = width;
 m.style.marginLeft = lmarg;
}