@media (min-width:356px) {
    .card-columns {
      column-count: 1;
    }
}

@media (min-width:576px) {
    .card-columns {
      column-count: 2;
    }
}
  @media (min-width:768px) {
    .card-columns {
      column-count: 2;
    }
}
@media (min-width:992px) {
    .card-columns {
      column-count: 2;
    }
}
@media (min-width:1200px) {
    .card-columns {
      column-count: 2;
    }
}