.cabecera_izq {
  background-color: #dcdcdc; 
	background-image: url(../imagenes/metal.jpg);
	width: 						100%;
	height: 					60px;
	position: 				absolute;
	top: 							0px;
	left: 						0px;
	border-bottom: 		5px solid #708090;
	z-index:-2;
}
.cabecera_der {
  background-color: #dcdcdc;
	background-image: url('../imagenes/metal.jpg');
  width:            10%;
  height: 					60px; 
  position: 				absolute; 
  top: 							0px;
  right: 						0px;
	border-bottom: 		5px solid #708090;
	text-align:				right;
	z-index:-1;
}
.tabla_titulo {
	width: 						600px;
	height: 					60px; 
	position: 				absolute; 
	top: 							0px;
	left: 						30px;
	vertical-align:		bottom;
	z-index: 3;
}