title: Custom class on SweetAlert2
body: <p>I am using <strong>SweetAlert2 version 10.13.0</strong> to display an alert box. My problem is that the custom class I placed is not working except for the margin. I referred to the documentation of SweetAlert2 still it is not working.</p>
  <p>Here is my code:</p>
  <pre><code>const swalWithBootstrapButtons = Swal.mixin({
      confirmButtonClass: 'btn btn-danger',
      cancelButtonClass: 'btn btn-dark mr-2',
      buttonsStyling: false,
  });
      
  swalWithBootstrapButtons.fire({
          title: 'Data Delete',
          text: 'Are you sure that you want to delete this data?',
          icon: 'info',
          showCancelButton: true,
          confirmButtonText: 'Delete Data',
          reverseButtons: true
      }).then((result) =&gt; {
          if (result.value) {
             // AJAX HERE    
          }
  });
  </code></pre>
  <p>I placed btn-danger the confirm button should be color red and the cancel button should be black but here is the output. The only thing that is working is the <strong>mr-2</strong> but the button color is not <em>(please refer to the output)</em>.</p>
  <p><a href="https://i.stack.imgur.com/ASyu0.png" rel="nofollow noreferrer">Output Here</a></p>
  <p>Am I missing something or is there anything that I haven't done yet?</p>