.card-img {
   width: 100%;
   padding-bottom: 100%;
   height: 0;
   position: relative;
}
.card-img .img {
    width: 100%;
    height: 100%;
    position: absolute;
    text-align: center;
}
.card-img .img img {
    max-width: 100%;
    max-height: 100%;
    object-fit: cover;
}
.card-body a {
    color: #555;
}