.card {
  margin-bottom: 15px;             /* space below every card */
  border-radius: 6px;              /* rounded corners */
  box-shadow: 0 2px 6px rgba(0,0,0,0.05); /* subtle shadow */
}

@media (max-width: 767.98px) {
  .col {
    flex: 0 0 100% !important;
    max-width: 100% !important;
  }
}