window.addEvent('domready', function(){

$$('#nav_main a').addEvents({
	mouseenter: function(){
		this.set('tween', {
			duration: 1000,
			transition: Fx.Transitions.Bounce.easeOut // This could have been also 'bounce:out'
		}).tween('width', '100px');
	},
	
	mouseleave: function(){
		this.set('tween', {}).tween('width', '175px');
	}
});

});