//create onDomReady Event
      window.onDomReady = initReady;
 
      // Initialize event depending on browser
      function initReady(fn)
      {
      	//W3C-compliant browser
      	if(document.addEventListener) {
          document.addEventListener("DOMContentLoaded", fn, false);
        }
      	//IE
      	else {
          document.onreadystatechange = function(){readyState(fn)}
        }
      }
 
      //IE execute function
      function readyState(func)
      {
      	// DOM is ready
      	if(document.readyState == "interactive" || document.readyState == "complete")
      	{
      		func();
      	}
      }
	  
 	window.onDomReady(onReady);
	function onReady() {
	  vertical();
	} 

function is_numeric(input){
    return typeof(input)=='number';
  }
  
function vertical() {
  var window_height = window.innerHeight;
  if (is_numeric(window_height)==false) {
    window_height = document.documentElement.clientHeight;
  }
  var height = 660;
    var margin = (window_height - height)/2 - 20;
	if (margin<0) {
      margin = 0;
	}	
  document.getElementById('main').style.marginTop = margin + "px";
}