
  <style>
    /* Estilos del modal */
    .modal {
      display: none;
      position: fixed;
      z-index: 1;
      left: 0;
      top: 0;
      width: 100%;
      height: 100%;
      overflow: auto;
      background-color: rgba(0,0,0,0.4);
    }

    .modal-content {
      background-color: #fefefe;
      margin: 10% auto;
      padding: 20px;
      border: 1px solid #888;
      width: 80%;
      max-width: 600px;
    }

    /* Estilos del botón de cierre */
    .close {
      color: #aaa;
      float: right;
      font-size: 28px;
      font-weight: bold;
    }

    .close:hover,
    .close:focus {
      color: black;
      text-decoration: none;
      cursor: pointer;
    }

    /* Estilos del spinner de carga */
    .spinner {
      border: 16px solid #f3f3f3;
      border-top: 16px solid #3498db;
      border-radius: 50%;
      width: 80px;
      height: 80px;
      animation: spin 2s linear infinite;
      margin: 20px auto;
    }

    @keyframes spin {
      0% { transform: rotate(0deg); }
      100% { transform: rotate(360deg); }
    }
  </style>