body {
    font-family: Arial, Helvetica, sans-serif;
    margin: 0;
    padding: 0;
    color: #222;
    background: #f9f9f9;
}
header, footer {
    background: #111;
    color: #fff;
    padding: 20px;
    text-align: center;
}
nav a {
    color: #fff;
    margin: 0 10px;
    text-decoration: none;
}
.container {
    max-width: 900px;
    margin: auto;
    padding: 20px;
    background: #fff;
}
button {
    background: #007bff;
    color: #fff;
    border: none;
    padding: 12px 20px;
    cursor: pointer;
}