[Vuejs]-How do I apply custom styles to a SweetAlert2 popup?

const showAlert = () => {
  Swal.fire("Update Successful", "Changes updated successfully!", "success");
}

.swal2-popup {
  background: #222 !important;
  border: 1px solid white !important;
  color: whitesmoke !important;
}

<script src="https://cdn.jsdelivr.net/npm/sweetalert2@11.6.0/dist/sweetalert2.all.js"></script>

<button onclick="showAlert()">Show Alert</button>