function velicinaProzora() {
  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;
  }
  ret = new Array();
  ret[0]=myWidth;
  ret[1]=myHeight;
  return ret;
}
function setContainerPos(){
	ws = velicinaProzora();
	if(document.getElementById('mainContainer')){
		mc = document.getElementById('mainContainer');
		v = mc.offsetHeight;
		if(ws[1]>v){
			margin = Math.round(v/2);
		}else{
			margin = Math.round(ws[1]/2);
		}
		mc.style.marginTop="-"+margin+"px";
	}
}