html {
    font-size: 12pt;
}
    @media (min-width: 640px) {
        html {font-size: 16pt; }
    }

    @media (min-width: 640px) {
        .two-columns-example {display: flex; }
        .two-columns-example > * {width: 50%; }
    }

img {
    max-width:100%;
}

body {
    margin-left: auto;
    margin-right: auto;
    width: 90%;
    max-width: 40rem;
}