window.addEvent('domready', function() {
	var naviBT = $('middleNav');
	
	function up() {
		naviBT.tween('height', '290px');
	}
	
	function down() {
		naviBT.tween('height', '0px');
	};
	
	naviBT.addEvent('click', function(e){
		up();
	});
	naviBT.addEvent('mouseleave', function(e){
		down();
	});

});