/* Overlay làm mờ nền */
    #popup-overlay {
      display: none;
      position: fixed;
      top: 0; left: 0;
      width: 100%; height: 100%;
      background-color: rgba(0, 0, 0, 0.6);
      z-index: 999;
      justify-content: center;
      align-items: center;
    }

    /* Nội dung popup */
    #popup {
      background: white;
      padding: 5px;
      border-radius: 8px;
      max-width: 90%;
      max-height: 90%;
      position: relative;
      box-shadow: 0 5px 5px rgba(0, 0, 0, 0.3);
    }

    /* Nút đóng */
    #popup .close-btn {
        position: absolute;
        bottom: 10px;
        right: 15px;
        font-size: 21px;
        cursor: pointer;
        color: #333;
        background-color: #fff;
        border-radius: 100%;
        padding: 0px 9px;
    }

    #popup img {
        width: 100%;
      max-height: 500px;
      height: auto;
      display: block;
}