* {
    box-sizing: border-box;
}

header,
main {
    margin-left: 1em;
}

h1 {
    margin: 0;
    padding: 0;
}

#program pre {
    white-space: pre-wrap;
}

@media screen and (min-width: 768px) {
    body {
        display: grid;
        grid-template-columns: 15em auto;
        grid-gap: 0;

    }

    header {
        grid-column: 1 / 3;
        grid-row: 1;
    }

    nav {
        position: -webkit-sticky;
        position: sticky;
        top: 0;
        height: 100vh;
        grid-column: 1;
        grid-row: 2;
    }

    main {
        grid-column: 2;
        grid-row: 2;
    }
}