$(function() {
    $("#head-nav li a").hover(function() {
        
        $el = $(this);
        $el.stop().animate({ backgroundPosition: "(0px 0px)", color: "#fff" }, 500);
    
    }, function() {
    
        $el = $(this);
        $el.stop().animate({ backgroundPosition: "(0px 100px)", color: "#000" }, 500);
    
    });

});