$(document).ready(function(){
	$("#hd_menu_btn span").click(function () {
			$("#hd_nav").slideToggle('fast');
	});
	$("#hd_menu_btn span").toggle(
			function(){
					$(this).css("background-image", "url(/smt/zen004/company/zen004/common/img/bt_hd_bar_menu_on.png)");
			},
			function(){
					$(this).css("background-image", "url(/smt/zen004/company/zen004/common/img/bt_hd_bar_menu.png)");
			}
	);
});