body {
    font-family: sans-serif;
    margin: 0;
    padding: 0;
    background-color: #f9f9f9;
    color: #333;
}
header, footer {
    background-color: #222;
    color: #fff;
    padding: 1em;
    text-align: center;
}
nav a {
    margin: 0 10px;
    color: #fff;
    text-decoration: none;
}
main {
    padding: 2em;
}
section {
    margin-bottom: 2em;
}