function showPopup(popup){
	
	var popupEl = $(popup);
	var popupFX = new Fx.Styles(popupEl, {duration:500, wait:false});
	var popupInitFX = new Fx.Styles(popupEl, {duration:0, wait:false});
	
	go();
	
	function go(){

		popupInitFX.start({
			'opacity': 0
		}).chain(function(){
			popupEl.style.display = 'block';
			popupFX.start({		
				'opacity': 1
			});
		});
	}
	
}

function hidePopup(popup){
	
	var popupEl = $(popup);
	var popupFX = new Fx.Styles(popupEl, {duration:500, wait:false});
	
	go();
	
	function go(){

		popupFX.start({		
			'opacity': 0
		}).chain(function(){
			popupEl.style.display = 'none';
		});
	}
	
}