html {
    font-size: 18px;
}

body {
    margin: 2em;
    line-height: 1.25;
}

body > div {
    margin: 0 auto;
    max-width: 50em;
}

.masthead {
    margin-bottom: 20px;
}

.masthead > .heading {
     font-size: 1.5rem;
}

.masthead > .subtext {
    font-size: smaller;
}

.example {
    font-style: italic;
}