* {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
        }
        body {
            min-height: 100vh;
            display: flex;
            justify-content: center;
            align-items: center;
            background-color: #f5f5f5;
            /*background-image: url('../background.jpg');*/
            /*background-size: cover; */
            /*background-position: center; */
            /*background-repeat: no-repeat;*/
        }
        .main-container {
            width: 100%;
            max-width: 500px;
            padding: 20px;
            text-align: center;
            
        }
        #qrcode-img {
          transform: rotate(-90deg);
        }
        #qrcode-img {
            max-width: 100%;
            height: auto;
            display: block;
            margin: 0 auto;
            border-radius: 8px;
            box-shadow: 0 2px 12px rgba(0,0,0,0.1);
        }
        /* 手机端 */
        @media (max-width: 480px) {
            .main-container {
                max-width: 100%;
                padding: 15px;
            }
        }
        /* 平板端 */
        @media (min-width: 481px) and (max-width: 768px) {
            .main-container {
                max-width: 400px;
            }
        }
        /* 电脑端 */
        @media (min-width: 769px) {
            .main-container {
                max-width: 450px;
            }
        }