    body {
      min-height: 100vh;
      display: flex;
      flex-direction: column;
    }
    
    .main-content {
      flex: 1;
      padding: 2rem 0;
    }
    
    #qr {
      margin: 1.5rem 0;
      text-align: center;
    }
    
    #qr canvas {
      background-color: white;
      border-radius: 10px;
      box-shadow: 0 4px 15px rgba(0,0,0,0.1);
      padding: 20px;
    }
    
    .url-error {
      display: none;
    }
    
    #downloadBtn {
      display: none;
    }
    
    footer {
      background-color: #f8f9fa;
      border-top: 1px solid #dee2e6;
      margin-top: auto;
      padding: 1.5rem 0;
    }
    
    /* Mobile Responsive */
    @media (max-width: 576px) {
      .main-content {
        padding: 1rem 0;
      }
      
      #qr canvas {
        padding: 15px;
        max-width: 100%;
        height: auto;
      }
      
      .form-control {
        font-size: 16px; /* ป้องกัน zoom ใน iOS */
      }
    }
        .manual-panel {
      position: fixed;
      top: 20px;
      right: 20px;
      z-index: 1000;
      max-width: 280px;
    }
    
    @media (max-width: 768px) {
      .manual-panel {
        position: relative;
        top: auto;
        right: auto;
        margin: 1rem 0;
        max-width: 100%;
      }
    }