body {
            margin: 0;
            font-family: 'Arial', sans-serif;
            background-color: #f0f2f5;
            color: #333;
        }

        .header {
            background-color: #003366;
            color: white;
            padding: 20px;
            text-align: center;
            font-size: 24px;
            font-weight: bold;
        }

        .layout {
            display: grid;
            grid-template-columns: 220px 1fr 220px;
            min-height: 100vh;
        }

        .sidebar-left, .sidebar-right {
            background-color: #e6eaf0;
            padding: 20px;
        }

        .sidebar-left a, .sidebar-right a {
            display: block;
            margin-bottom: 15px;
            color: #003366;
            text-decoration: none;
            font-weight: bold;
        }

        .sidebar-left a:hover, .sidebar-right a:hover {
            color: #0055a5;
        }

        .content {
            padding: 40px;
            background-color: white;
            border-radius: 10px;
            margin: 20px;
            box-shadow: 0 4px 8px rgba(0,0,0,0.1);
        }

        .success, .error {
            padding: 15px;
            border-radius: 5px;
            margin-bottom: 20px;
            font-size: 18px;
        }

        .success {
            background-color: #d4edda;
            color: #155724;
            border: 1px solid #c3e6cb;
        }

        .error {
            background-color: #f8d7da;
            color: #721c24;
            border: 1px solid #f5c6cb;
        }

        .button {
            display: inline-block;
            padding: 10px 20px;
            background-color: #006400;
            color: white;
            text-decoration: none;
            border-radius: 5px;
            margin-right: 10px;
        }

        .button:hover {
            background-color: #004d00;
        }

        .footer {
            background-color: #003366;
            color: white;
            text-align: center;
            padding: 15px;
        }

        @media (max-width: 900px) {
            .layout {
                grid-template-columns: 1fr;
            }

            .sidebar-left, .sidebar-right {
                display: none;
            }

            .content {
                margin: 20px auto;
            }
        }