html, body {
    height: 100%;
    min-height: 100%;
}

html {
    font-size: 16px;
    font-family: monospace;
}

body {
    align-items: center;
    color: midnightblue;
    display: flex;
    justify-content: center;
    line-height: 1.5;
    margin: 0;
}

body > div {
    max-width: 40rem;
    width: 100%;
}

h1, h2, h3, h4 {
    line-height: 1.15;
}      

main {
    padding: 2rem;
}