.bg-home {
    height: 100vh;
    background: url('/assets/images/gb/mob.jpg') no-repeat;
    background-size: cover;
}
.conc {
    text-align: center;
}

@media (min-width: 550px) {
    .bg-home {
        background: url('/assets/images/gb/desk.jpg') no-repeat;
        background-size: cover;
    }
}