qr-code {
    display: block;
    width: 720px;
    margin-left: auto;
    margin-right: auto;
}

qr-code canvas {
    max-width: calc(100vw - 32px);
    max-height: calc(50vw - 32px);
    width: 300px;
    display: block;
    margin: 32px auto;
    cursor: pointer;
}