.semaforo {
	width:16px;
	height:16px;
	background-image: url("semaforos.png");
	background-repeat: no-repeat;
}

.gris 		{ background-position: 0px 0px; 		}
.rojo 		{ background-position: 0px  -17px; 	}
.amarillo 	{ background-position: 0px  -34px; 	}
.verde 		{ background-position: 0px  -51px; 	}