$(document).ready(function() { 
    var imgWidth = 528;
    var imgHeight = 216;
    var menuImage = "background: transparent url('/images/mainpage/main_menu_bar.gif') 0 0 no-repeat;";
    // Find the height of a single menu bar from the map
    var menuBarHeight = Math.round( imgHeight / ($('.sf-menu li').size() + 1) ); 
    
    $('ul.sf-menu').parent().attr({ style: 'width: ' + imgWidth + 'px; height: ' + menuBarHeight + 'px;' + menuImage});
    $('ul.sf-menu a').css( "height",  (menuBarHeight + "px") );
    $('ul.sf-menu a').html(" ");
    
    $('ul.sf-menu').superfish();  
    
    $('ul.sf-menu a').each(function(index) {         
        $(this).hover( 
            function() { 
                var menuBkgHeight = (index + 1) * ( -1 * menuBarHeight); 
                $('ul.sf-menu').parent().css( "background-position", "0 " + (menuBkgHeight + "px")  ); 
            }, 
            function() { $('ul.sf-menu').parent().css( "background-position", "0 0"  ); } 
        );     
    }); 
});