<div class="accordion" id="accordionExample">
  <div class="card">
    <div class="card-header" id="headingOne">
      <button class="btn btn-link" type="button" data-toggle="collapse" data-target="#collapseOne"
              aria-expanded="true" aria-controls="collapseOne">
        Collapsible Group Item #1
      </button>
    </div>
    <div id="collapseOne" class="collapse show" aria-labelledby="headingOne"
         data-parent="#accordionExample">
      <div class="card-body">...</div>
    </div>
  </div>
  <div class="card">
    <div class="card-header" id="headingTwo">
      <button class="btn btn-link collapsed" type="button" data-toggle="collapse"
              data-target="#collapseTwo" aria-expanded="false" aria-controls="collapseTwo">
        Collapsible Group Item #2
      </button>
    </div>
    <div id="collapseTwo" class="collapse" aria-labelledby="headingTwo"
         data-parent="#accordionExample">
      <div class="card-body">...</div>
    </div>
  </div>
  <div class="card">
    <div class="card-header" id="headingThree">
      <button class="btn btn-link collapsed" type="button" data-toggle="collapse"
              data-target="#collapseThree" aria-expanded="false" aria-controls="collapseThree">
        Collapsible Group Item #3
      </button>
    </div>
    <div id="collapseThree" class="collapse" aria-labelledby="headingThree"
         data-parent="#accordionExample">
      <div class="card-body">...</div>
    </div>
  </div>
</div>