Reference UI Playground

This page opens the bundled formulon-cell playground in an overlay child window. It is deliberately framed as a reference integration surface: Formulon remains the headless calculation engine, while this UI exists to make the browser build inspectable through spreadsheet workflows.

The playground mounts formulon-cell with its default full chrome and a seeded workbook. Try selection, formula editing, keyboard navigation, context menus, dialogs, and theme switching. Feature coverage is partial, UI/UX does not aim for exact Excel parity, and UI bugs may remain. For headless usage, continue with the Formulon runtime and API pages rather than treating this UI as the required integration path.