/* Overlay ครอบเต็มหน้าจอ */
    #overlay {
      position: fixed;
      inset: 0;
      width: 100%; height: 60vh;
      background: rgba(0,0,0,0.9);
      display: none; /* ซ่อนเริ่มต้น */
      justify-content: center;
      align-items: center;
      z-index: 999;
    }
    #scannerdiv {
      position: fixed;
      top: 3px; left: 0%;
      width: 15%; height: 5%;
      display: flex;
      justify-content: center;
      align-items: center;
      z-index: 1000;
    }
    /* Camera box responsive */
    #reader {
      width: 100%;
      max-width: 100%;
      height: 100%;
      max-height: 100%;
    }
    #closeBtn {
      position: absolute;
      top: 100%; right: 5%;
      padding: 10px 15px;
      background: red;
      color: white;
      border: none;
      border-radius: 5px;
      cursor: pointer;
      z-index: 100;
    }
    #scanBtn {
      position: absolute;
      top: 0%; right: 0%;
      padding: 10px 15px;
      background: red;
      color: white;
      border: none;
      border-radius: 5px;
      cursor: pointer;
      z-index: 102;
    }