var indexes = { 'home' 		: 7,
				'menus'		: 6,
				'catering'	: 5,
				'upper'		: 4,
				'deals'		: 3,
				'contact'	: 2
			  };

var mouseOver = function(image){
	id = image.id;
	image.src = 'images/buttons/'+id+'_rollover.png';
	image.style.zIndex = 8;
	image.style.top = '5px';
}

var mouseOut = function(image){
	id = image.id;
	image.src = 'images/buttons/'+id+'.png';
	image.style.zIndex = indexes[id];
	image.style.top = '';
	
}

window.onload = (function(){
	var nav = document.getElementById('nav')
	var navImages = nav.getElementsByTagName('img');
	for(var i = 0; i < navImages.length; i++){
		navImages[i].onmouseover = function(){
			mouseOver(this);
		};
		navImages[i].onmouseout = function(){
			mouseOut(this);
		};
	}
});