Выпадающие списки (select)

<!-- Latest compiled and minified CSS -->
<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/bootstrap-select/1.11.2/css/bootstrap-select.min.css">

<!-- Latest compiled and minified JavaScript -->
<script src="https://cdnjs.cloudflare.com/ajax/libs/bootstrap-select/1.11.2/js/bootstrap-select.min.js"></script>

<!-- (Optional) Latest compiled and minified JavaScript translation files -->
<script src="https://cdnjs.cloudflare.com/ajax/libs/bootstrap-select/1.11.2/js/i18n/defaults-*.min.js"></script>


<select class="selectpicker">
  <option>Mustard</option>
  <option>Ketchup</option>
  <option>Relish</option>
</select>

<script>
$('.selectpicker').selectpicker({
  style: 'btn-info',
  size: 4
});
</script>