body {
    font-family: Arial, sans-serif;
    margin: 0;
    padding: 0;
}

header {
    background-color: #333;
}

nav ul {
    list-style: none;
    display: flex;
    padding: 0;
    margin: 0;
}

nav ul li {
    margin: 0;
}

nav ul li a {
    color: white;
    text-decoration: none;
    padding: 15px 20px;
    display: block;
}

nav ul li a:hover {
    background-color: #555;
}

nav ul li a.active {
    background-color: #007BFF;
}

main {
    padding: 20px;
}