window.addEvent('domready', function(){
        var fxs = [];
        var keys = ['intro', 'explain', 'explore', 'get', 'help'];
        keys.each(function(key, i) {
                fxs[i] = new Fx.Style(key + '-slide', 'opacity', {duration: 1300});
        });
        keys.each(function(key, i) {
                if (key != 'intro') {
                        $('menu-' + key).addEvent('click', function() {
                                fxs.each(function(fx) {
                                        if (fx == fxs[i]) return;
                                        fx.start(0);
                                });
                                fxs[i].start(1);
                        });
                }
        });
});