body {
    margin: 0;
}

.card {
    width: min(720px, 90vw);
    margin: 40px auto 0;
    padding: 30px;
    border: 1px solid;
    box-sizing: border-box;
}

@media (max-width: 640px) {
    body {
        min-height: 100dvh;
        padding: 28px 16px;
    }
    
    .card {
        width: 100%;
        min-height: calc(100dvh - 76px);
        margin: 76px auto;
        padding: 24px 20px;
    }
}