@media (max-width: 768px) { 
    .card-columns {
        column-count: 2; 
    }
}
@media (min-width: 768px) and (max-width: 992px) { 
    .card-columns {
            column-count: 3; 
    } 
}
@media (min-width: 992px) { 
    .card-columns {
        column-count: 4; 
    } 
}
.post-free {
    position: absolute;
    top: 1px;
    right: 1px;
    background: red;
    color: #FFF;
    padding: 1px 3px;
}