<div class="alert alert-dismissible" role="alert">
  This is an alert
  <button type="button" class="close" data-dismiss="alert" aria-label="Close">
    <span aria-hidden="true">×</span>
  </button>
</div>

<div class="alert alert-success alert-dismissible" role="alert">
  This is an alert
  <button type="button" class="close" data-dismiss="alert" aria-label="Close">
    <span aria-hidden="true">×</span>
  </button>
</div>

<div class="alert alert-danger alert-dismissible" role="alert">
  This is an alert
  <button type="button" class="close" data-dismiss="alert" aria-label="Close">
    <span aria-hidden="true">×</span>
  </button>
</div>

<div class="alert alert-warning alert-dismissible" role="alert">
  This is an alert
  <button type="button" class="close" data-dismiss="alert" aria-label="Close">
    <span aria-hidden="true">×</span>
  </button>
</div>

<div class="alert alert-info alert-dismissible" role="alert">
  This is an alert
  <button type="button" class="close" data-dismiss="alert" aria-label="Close">
    <span aria-hidden="true">×</span>
  </button>
</div>