$(document).ready(function () { 
     
    $('#nav li').hover(
        function () {
            //show its submenu
            $('ul', this).slideDown(10); 
        }, 
        function () {
            //hide its submenu
            $('ul', this).slideUp(10);
        }
    );


	$('.hover_first').hover(
        function () {
            //show its submenu
			$(this).addClass('round_menu');
 
        }, 
        function () {
            //hide its submenu
			$(this).removeClass('round_menu');
        }
    );

	
	$('#nav ul.hover_sub').hover(
        function () {
            //show its submenu
			$(this).addClass('round_submenu');
 
        }, 
        function () {
            //hide its submenu
			$(this).removeClass('round_submenu');
        }
    );
     
});