<div class="modal is-open">
    <div class="modal-window">
      <h2>Alert</h2>
      <p>Are you sure? Aenean eu leo quam. Pellentesque ornare sem lacinia quam venenatis vestibulum.</p>
      <a href="#" class="btn btn--primary">Yes</a>
      <a href="#" class="btn btn--secondary">No</a>
    </div>
    <div class="modal-overlay"></div>
  </div>