<p>
  <a href="#" class="button bg-dark">dark</a>
  <a href="#" class="button bg-primary">primary</a>
  <a href="#" class="button bg-secondary">secondary</a>
  <a href="#" class="button bg-info">info</a>
  <a href="#" class="button bg-success">success</a>
  <a href="#" class="button bg-warning">warning</a>
  <a href="#" class="button bg-danger">danger</a>
</p>