<div class="dropdown-click">
  <button onclick="myFunction()" class="button black">Click Me!</button>
  <div id="Demo" class="dropdown-content bar-block border">
    <a href="#" class="bar-item button">Link 1</a>
    <a href="#" class="bar-item button">Link 2</a>
    <a href="#" class="bar-item button">Link 3</a>
  </div>
</div>
 
<script>
function myFunction() {
  var x = document.getElementById("Demo");
  if (x.className.indexOf("show") == -1) { 
    x.className += " show";
  } else {
    x.className = x.className.replace("show", "");
  }
}
</script>