
        /* Responsive Design */
        @media (max-width: 768px) {
            .notebook-container {
                padding: 12px;
            }
            
            .cell-prompt {
                width: 60px;
                font-size: 11px;
            }
            
            .toolbar-group {
                flex-wrap: wrap;
            }
        }
        
        /* Accessibility */
        .sr-only, .visually-hidden {
            position: absolute;
            width: 1px;
            height: