body {
    font-family: Arial, sans-serif;
    margin: 0;
    padding: 0;
    display: flex;
    flex-direction: column;
    min-height: 100vh;
}

header {
    background-color: #333;
    color: white;
    padding: 1em 0;
}

header nav ul {
    list-style: none;
    margin: 0;
    padding: 0;
    display: flex;
    justify-content: center;
}

header nav ul li {
    margin: 0 1em;
}

header nav ul li a {
    color: white;
    text-decoration: none;
}

main {
    flex: 1;
    padding: 2em;
}

footer {
    background-color: #333;
    color: white;
    text-align: center;
    padding: 1em 0;
}

/* Responsive design */
@media (max-width: 600px) {
    header nav ul {
        flex-direction: column;
    }

    header nav ul li {
        margin: 0.5em 0;
    }
}