(function ($) {
$.fn.magicLine = function(container){
    var $el, leftPos, newWidth,
        $mainNav = $("#"+container);
    $mainNav.append('<li id="magic-line'+container+'" class="magic_line"></li>');
    
    var $magicLine = $("#magic-line"+container);
    
    $magicLine
        .width($("#"+container+" li a.act").parent().width())
        .css("left", $("#"+container+" li a.act").position().left)
        .data("origLeft", $magicLine.position().left)
        .data("origWidth", $magicLine.width());
        
    $("#"+container+" li a").hover(function() {
        $el = $(this);
        leftPos = $el.position().left;
        newWidth = $el.parent().width();
        
        $magicLine.stop().animate({
            left: leftPos,
            width: newWidth
        });
    }, function() {
        $magicLine.stop().animate({
            left: $magicLine.data("origLeft"),
            width: $magicLine.data("origWidth")
        });    
    });
};
})(jQuery);