@media all {
    div.bann-colores {
		background-repeat: no-repeat;
		background-image: url("../img-tb/PORTADA-COLORES-2.jpg");
		background-size: cover;
		background-position: center; 
		margin: auto;		
	}
}

@media all and (orientation:portrait) /*para pantallas verticales-moviles*/ {
	
	div.bann-colores {
		background-repeat: no-repeat;
		background-image: url("../img-tb/PORTADA-COLORES-MOV-2.jpg");
		background-size: cover;
		background-position: center; 
		margin: auto;		
	}
}