.card-thumbnail {
    width: 100%;
    height: 40vw;
    object-fit: cover;
}

.card-thumbnail:hover {
    bkit-box-shadow: 0px 0px 15px 0px rgba(0,0,0,0.4);
    -moz-box-shadow: 0px 0px 15px 0px rgba(0,0,0,0.4);
    box-shadow: 0px 0px 15px 0px rgba(0,0,0,0.4);
}

@media (min-width: 576px) {
    .card-thumbnail {
        height: 40vw;
    }
}

@media (min-width: 768px) {
    .card-thumbnail {
        height: 30vw;
    }
}

@media (min-width: 992px) {
    .card-thumbnail {
        height: 20vw;
    }
}

@media (min-width: 1200px) {
    .card-thumbnail {
        height: 15vw;
    }
}