style.css

body {
    font-family: ui-sans-serif, sans-serif;
    max-width: 40em;
    margin: auto;
    padding: 1em;
    position: relative;
    line-height: 1.5;
}

h1 {
    text-align: center;
}

#logo {
    width: 100%;
}

@media (min-width: 25em) {
    #logo {
        float: left;
        margin: 0 1em 0.5em 0;
        max-width: 100%;
        width: 10em;
    }
}

nav {
    margin: 1.35em 0;
}

nav h2 {
    margin-bottom: 0.5em;
}

nav ul {
    margin: 0;
}

@media (min-width: 67em) {
    body {
        max-width: 65em;
    }

    nav {
        float: right;
        margin-top: 0;
        position: sticky;
        top: 1em;
        width: 22.5em;
    }

    nav h2 {
        margin-top: 0;
        margin-left: 0.5em;
    }

    main {
        margin-right: 22.5em;
    }
}

#snapshot {
    margin: 0;
}

#snapshot img {
    width: 100%;
}

#snapshot figcaption {
    font-style: italic;
    margin-top: 0.25em;
    text-align: center;
}