@media (max-width: 768px) { 
  .modal-dialog {
      max-width: 328px; 
      margin: auto !important; 
  }
  
  .modal-content {
      width: 100%; 
      max-width: 328px;
  }

  .modal-body {
      width: 100%;
      max-height: 280px;
  }
}