Tempus-dominus and sweetalert2

Question

I've created a modal with sweetalert2 and the input field is a datepicker widget from tempusdominus but the calendar shows behind the buttons of the modal as the following image:

My code is the following:

Swal.fire({
   title: 'Pay',
   html: '<input type="text" name="payment_day" class="datetimepicker-input swal2-input" autocomplete="off" data-toggle="datetimepicker" data-target="#payment_day" id="payment_day">',
   showCancelButton: true,
   confirmButtonColor: '#3085d6',
   cancelButtonColor: '#d33',
   confirmButtonText: 'Confirm',
   cancelButtonText: 'Cancel',
   onOpen: function () {
     $('#payment_day').datetimepicker({
       format: 'L'
     });
   },
}).then((result) => {});

Answer 1

and now :

$(function() {
  Swal.fire({
   title: 'Pay',
   html: '<input type="text" name="payment_day" class="datetimepicker-input swal2-input" autocomplete="off" data-toggle="datetimepicker" data-target="#payment_day" id="payment_day">',
   showCancelButton: true,
   confirmButtonColor: '#3085d6',
   cancelButtonColor: '#d33',
   confirmButtonText: 'Confirm',
   cancelButtonText: 'Cancel',
   onOpen: function () {
     $('#payment_day').datetimepicker({
       format: 'L'
     });
   },
}).then((result) => {});
});

.swal2-content
{
      z-index: 2!important;
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>

<script src="https://cdnjs.cloudflare.com/ajax/libs/limonte-sweetalert2/7.33.1/sweetalert2.all.js"></script>


<script src="https://cdn.jsdelivr.net/npm/moment@2.20.1/moment.min.js"></script>

<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.12.9/umd/popper.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/4.1.1/js/bootstrap.min.js"></script>
<script src="https://rawgit.com/tempusdominus/bootstrap-4/master/build/js/tempusdominus-bootstrap-4.js"></script>


<link href="https://rawgit.com/tempusdominus/bootstrap-4/master/build/css/tempusdominus-bootstrap-4.css" rel="stylesheet"/>
<link href="https://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/4.1.1/css/bootstrap.min.css" rel="stylesheet"/>
<link href="https://cdnjs.cloudflare.com/ajax/libs/limonte-sweetalert2/7.33.1/sweetalert2.min.css" rel="stylesheet"/>
<link href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/4.7.0/css/font-awesome.min.css" rel="stylesheet"/>