body { font-family: sans-serif; margin: 0; display: flex; height: 100vh; }
        nav { width: 250px; background: #2c3e50; color: white; padding: 20px; }
        nav a { display: block; color: #ecf0f1; padding: 10px; text-decoration: none; border-bottom: 1px solid #34495e; }
        nav a:hover { background: #34495e; }
        .main-content { flex: 1; padding: 20px; overflow-y: auto; background: #f4f7f6; }
        iframe { border: none; width: 100%; height: 90vh; background: white; }