html, body {
    height: 100%;
}

.box {
    filter: progid:DXImageTransform.Microsoft.gradient(startColorstr='#6699FF', endColorstr='#6699FF'); /*  IE */
    background-image: linear-gradient(bottom, #6699FF 0%, #6699FF 100%);
    background-image: -o-linear-gradient(bottom, #6699FF 0%, #6699FF 100%);
    background-image: -moz-linear-gradient(bottom, #6699FF 0%, #6699FF 100%);
    background-image: -webkit-linear-gradient(bottom, #6699FF 0%, #6699FF 100%);
    background-image: -ms-linear-gradient(bottom, #6699FF 0%, #6699FF 100%);
    margin: 0 auto;
    position: relative;
    width: 100%;
    height: 100%;
}
#qrCode {
    
    height: 20px;
}
.login-box {
    width: 100%;
    max-width: 500px;
    height: 400px;
    position: absolute;
    top: 50%;
    margin-top: -200px;
    /*设置负值，为要定位子盒子的一半高度*/
}

@media screen and (min-width:500px) {
    .login-box {
        left: 50%;
        /*设置负值，为要定位子盒子的一半宽度*/
        margin-left: -250px;
    }
}

.form {
    width: 100%;
    max-width: 500px;
    height: 275px;
    margin: 25px auto 0px auto;
    padding-top: 25px;
}

.login-content {
    height: 300px;
    width: 100%;
    max-width: 500px;
    background-color: rgba(255, 250, 2550, .6);
    float: left;
}


.input-group {
    margin: 0px 0px 30px 0px !important;
}

.form-control,
.input-group {
    height: 40px;
}

.form-group {
    margin-bottom: 0px !important;
}

.login-title {
    padding: 20px 10px;
    background-color: rgba(0, 0, 0, .6);
}

    .login-title h1 {
        margin-top: 10px !important;
    }

    .login-title small {
        color: #fff;
    }

.link p {
    line-height: 20px;
    margin-top: 30px;
}

.btn-sm {
    padding: 8px 24px !important;
    font-size: 16px !important;
}