.qrcode {
}
.qrcode img {
    /* Override "block" display which qrcode.js sets by default, to allow
       proper centering */
    display: inline !important;
    height: 70% !important;
    width: auto !important; 
    margin-left: auto;
    margin-right: auto;
    background-color: white !important;
    padding: 1em;
}