function menusToogle(){
	$$('.parent-nav-link').each(function(e, index){
		Event.observe(e, 'click', function(){
			subnav = $('sub-navigation-' + index);
			if(subnav.visible()){
				Effect.BlindUp($('sub-navigation-'+index), {duration:0.5});
			}
			else{
				Effect.BlindDown($('sub-navigation-'+index), {duration:0.5});	
			}
		});
	});
}

Event.observe(window, 'load', menusToogle);