body {
    margin: 0;
    padding: 20px;
    font-family: Arial, sans-serif;
}

.container {
    max-width: 800px;
    margin: 0 auto;
}

nav {
    margin: 20px 0;
    padding: 10px;
    background: #f0f0f0;
    border-radius: 5px;
}

nav a {
    margin-right: 15px;
    text-decoration: none;
    color: #333;
    padding: 5px 10px;
}

nav a.active {
    background: #2196F3;
    color: white;
    border-radius: 3px;
}

.content {
    padding: 20px;
    background: #fff;
    border-radius: 5px;
    box-shadow: 0 2px 5px rgba(0,0,0,0.1);
}