jQuery(document).ready(function($) { 
	
    // alternate colors of tr
    alternateRows();
    
    function alternateRows() {
    	$('#tb-1 tr:even').addClass('even');
        $('#tb-1 tr:odd').addClass('odd');
    }
    
    // function align center for menu want to align
    function alignSubMenu(menu) {
        var main_length = $(menu).find('li > a:first-child').width();
        var nav_offsetleft = $('#nav').offset().left;
        var padleft = $(menu).find('li > a:first-child').offset().left - nav_offsetleft;
        
        var sub = $(menu).find('.sub:first').width();
        var left = padleft + main_length/2;
        var right = $('#nav').width() - left;         
                       
        if (left>sub/2 && right>sub/2) {
            $(menu).find('.sub:first').css({'margin-left': left-sub/2 - 5 + 'px' });                
        }
        else if (right<sub/2){            
            $(menu).find('.sub:first').css({'margin-left': left-sub + right - 10 + 'px' });

        }
        else if (left<sub/2) {            
            $(menu).find('.sub:first').css({'margin-left': 0 + 'px' });
        }
        else {            
            $(menu).find('.sub:first').css({'margin-left': 0 + 'px' });
        }
    };        
    
    // get current menu and align this
    var currentMenu = $('ul.select.active');
    alignSubMenu(currentMenu);
    
    
    // align center for menu:hover
    $('#nav .select').hover(
        function(){                               
            if ( !$(this).hasClass('active') ){                      
                $('.sub_active').css({'display':'none'});
            } 
            $('ul.select.active').removeClass('active');     
            alignSubMenu(this);
        }, 
        function(){
            currentMenu.addClass('active');
            $('.sub_active').css({'display':'block'});                    
        }
    );
});