function tamanyoLetras(){

	var selector='#contenido *';
	var nombre="letra";
	var tamanyo=0;
	
	function cambio(coef){
		$$(selector).each(function(el){
    		try{
    		    el.setStyle('fontSize',el.tamanyo_original+tamanyo);
    			el.setStyle('lineHeight',el.altura_original+tamanyo);
    		}catch(ex){}
		});	
	}
	
	function aumentar(){
		if(tamanyo<30){
			tamanyo+=1;
			cambio();
		}
	}
	
	function reducir(){
		if(tamanyo>-3){
			tamanyo-=1;
			cambio();
		}
	}
	
	function normal(){
		$$(selector).each(function(el){
    		try{
    			el.setStyle('fontSize','');
    			el.setStyle('lineHeight','');
    		}catch(ex){}
		});	
	}
	
	function cargar() {
		$$(selector).each(function(el){
	  	el.tamanyo_original=el.getStyle('fontSize').toInt();
	  	el.altura_original=el.getStyle('lineHeight').toInt();
	  });
		$$('.aumentar_letra').each(function(el){
			el.addEvent('click',aumentar);
		});
		$$('.disminuir_letra').each(function(el){
			el.addEvent('click',reducir);
		});
		$$('.normal_letra').each(function(el){
			el.addEvent('click',normal);
		});
	}
	
window.addEvent('domready',cargar);	
}

tamanyoLetras();