* {
    box-sizing: border-box;
}

body {
    margin: 0;
    display: flex;
    flex-direction: column;
    min-height: 100vh;
}

header, main, footer {
    max-width: 800px;
    width: 100%;
    margin: 0 auto;
    padding: 1rem;
}

pre {
    overflow-x: auto;
}

main {
    flex: 1;
}