.sombra_arriba {
	background-image: url(imagenes/sombra_arriba.gif);
	background-repeat: no-repeat;
	background-position: center bottom;
}
.sombra_abajo {

	background-image: url(imagenes/sombra_abajo.gif);
	background-repeat: no-repeat;
	background-position: center top;
}
.sombra_dcha {
	background-image: url(imagenes/sombra_dcha.gif);
	background-repeat: repeat-y;
	background-position: left;
}
.sombra_izq {
	background-image: url(imagenes/sombra_izq.gif);
	background-repeat: repeat-y;
	background-position: right;
}