<div class="modal fade" id="addLinkModal" tabindex="-1" role="dialog" aria-labelledby="exampleModalLabel" aria-hidden="true">
  <div class="modal-dialog modal-dialog-centered" role="document">
    <div class="modal-content">
      <div class="modal-header">
        <h5 class="modal-title" id="exampleModalLabel">Add Link</h5>
        <button type="button" class="close" data-dismiss="modal" aria-label="Close">
          <span aria-hidden="true">&times;</span>
        </button>
      </div>
      <div class="modal-body">
        <input id="link-form" type="text" class="form-control" placeholder="https://example.com" style="width: 80%; float: left;">
        <button id="link-btn" type="button" class="btn btn-primary" onclick="addUrl();" style="float: right;">Add</button>
      </div>
    </div>
  </div>
</div>