Sandkasten

<button class="btn btn-link btn-block text-left" type="button" data-toggle="collapse" data-target="#collapseOne" aria-expanded="true" aria-controls="collapseOne"> Collapsible Group Item #1 </button>

       Some placeholder content for the first accordion panel. This panel is shown by default, thanks to the .show class.

<button class="btn btn-link btn-block text-left collapsed" type="button" data-toggle="collapse" data-target="#collapseTwo" aria-expanded="false" aria-controls="collapseTwo"> Collapsible Group Item #2 </button>

       Some placeholder content for the second accordion panel. This panel is hidden by default.

<button class="btn btn-link btn-block text-left collapsed" type="button" data-toggle="collapse" data-target="#collapseThree" aria-expanded="false" aria-controls="collapseThree"> Collapsible Group Item #3 </button>

       And lastly, the placeholder content for the third and final accordion panel. This panel is hidden by default.