body {
    margin: 40px auto;
    max-width: 700px;
    line-height: 1.6;
    font-size: 18px;
    color: #444;
    padding: 0 16px;
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto,
    Helvetica, Arial, sans-serif;
}
h1,h2,h3 { line-height: 1.2 }
* { background-color: #eeeeee; }