responsive card deck bootstrap 4 code example

Example 1: edit card-deck breakingpoints bootstrap

.card-deck {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    grid-gap: .5rem;
}

Example 2: responsive card header

<div class="card" style="width: 18rem;">
  <div class="card-header">
    Featured
  </div>
  <ul class="list-group list-group-flush">
    <li class="list-group-item">Cras justo odio</li>
    <li class="list-group-item">Dapibus ac facilisis in</li>
    <li class="list-group-item">Vestibulum at eros</li>
  </ul>
</div>