#img-holder-1 {
	background-image: url("../img/lf-cover.jpg");
}
#img-holder-2 {
	background-image: url("../img/uf-cover.jpg");
}
#img-holder-3 {
	background-image: url("../img/mf-cover.jpg");
}
#img-holder-4 {
	background-image: url("../img/pf-cover.jpg");
}
#img-holder-5 {
	background-image: url("../img/pf-cover.jpg");
}

@media only screen and (max-width: 1024px) {
    /* For mobile phones: */
	#img-holder-1 {
		background-image: url("../img/lf-tab-cover.jpg");
	}
	#img-holder-2 {
		background-image: url("../img/uf-tab-cover.jpg");
	}
	#img-holder-3 {
		background-image: url("../img/mf-tab-cover.jpg");
	}
	#img-holder-4 {
		background-image: url("../img/pf-tab-cover.jpg");
	}
	#img-holder-5 {
		background-image: url("../img/pf-tab-cover.jpg");
	}
}

@media only screen and (max-width: 600px) {
    /* For mobile phones: */
	#img-holder-1 {
		background-image: url("../img/lf-mob-cover.jpg");
	}
	#img-holder-2 {
		background-image: url("../img/uf-mob-cover.jpg");
	}
	#img-holder-3 {
		background-image: url("../img/mf-mob-cover.jpg");
	}
	#img-holder-4 {
		background-image: url("../img/pf-mob-cover.jpg");
	}
	#img-holder-5 {
		background-image: url("../img/pf-mob-cover.jpg");
	}
}