function show_popup(){
	document.getElementById('popup_layer').style.display='block';
	my_viewport=viewport;
 	my_viewport.getAll();
	popup_left=(my_viewport.width-800)/2
	document.getElementById('popup_layer').style.left=popup_left+"px";
	window.setTimeout("hide_popup()",12000);
}

function hide_popup(){
	document.getElementById('popup_layer').style.display='none';
}

viewport = {
  getWinWidth: function () {
    this.width = 0;
    if (window.innerWidth) this.width = window.innerWidth - 18;
    else if (document.documentElement && document.documentElement.clientWidth) 
  		this.width = document.documentElement.clientWidth;
    else if (document.body && document.body.clientWidth) 
  		this.width = document.body.clientWidth;
  },
 
  getWinHeight: function () {
    this.height = 0;
    if (window.innerHeight) this.height = window.innerHeight - 18;
  	else if (document.documentElement && document.documentElement.clientHeight) 
  		this.height = document.documentElement.clientHeight;
  	else if (document.body && document.body.clientHeight) 
  		this.height = document.body.clientHeight;
  },
 
  getScrollX: function () {
    this.scrollX = 0;
  	if (typeof window.pageXOffset == "number") this.scrollX = window.pageXOffset;
  	else if (document.documentElement && document.documentElement.scrollLeft)
  		this.scrollX = document.documentElement.scrollLeft;
  	else if (document.body && document.body.scrollLeft) 
  		this.scrollX = document.body.scrollLeft; 
  	else if (window.scrollX) this.scrollX = window.scrollX;
  },
 
  getScrollY: function () {
    this.scrollY = 0;    
    if (typeof window.pageYOffset == "number") this.scrollY = window.pageYOffset;
    else if (document.documentElement && document.documentElement.scrollTop)
  		this.scrollY = document.documentElement.scrollTop;
  	else if (document.body && document.body.scrollTop) 
  		this.scrollY = document.body.scrollTop; 
  	else if (window.scrollY) this.scrollY = window.scrollY;
  },
 
  getAll: function () {
    this.getWinWidth(); this.getWinHeight();
    this.getScrollX();  this.getScrollY();
  }
 
}