html {
    background-color: #eee;
    padding: 0 calc(50% - 25rem);
}

@media (min-width: 640px) {
    body {
        padding: 1rem 4rem;
    }
}

body {
    background-color: #fff;
    min-height: 100%;
}

pre {
    background-color: #f8f8f8;
    color: #333;
    padding: 0.75em .625em;
}

.coupons {
    display: flex;
    flex-wrap: wrap;
    justify-content: space-between;
}

footer {
    font-size: .8em;
    border-top: #f8f8f8 1px solid;
    padding-top: 1rem;
    margin-top: 2rem;
}

footer > p {
    text-align: justify;
}

footer > div {
    display: flex;
    justify-content: space-between;
}