/* overlay (αυτό που έδωσες) */
        .simple-message-modal {
          position: fixed;
          inset: 0;
          background: rgba(0,0,0,0.7);
          opacity: 0;
          visibility: hidden;
          transition: opacity 0.3s ease;
          z-index: 99999;

          display: flex;
          justify-content: center;
          align-items: center;
        }

        /* όταν είναι ενεργό */
        .simple-message-modal.active {
          opacity: 1;
          visibility: visible;
        }

        /* κουτί */
        .simple-message-content {
          background: #fff;
          padding: 5% 2%;
          border-radius: 12px;
          text-align: center;
          width: 80%;
          box-shadow: 0 4px 15px rgba(0,0,0,0.3);
        }

        .simple-message-content p {
          margin: 0 0 15px;
          font-size: 18px;
          line-height: 1.5;
        }        
        
        .simple-message-modal .close-btn {
          margin-top: 15px;
          background: #dc3545;
          font-size: 1.5rem;
        }