I see this is a sophisticated financial management panel for "Stare Czasy" (a restaurant). It's a Chrome extension panel that tracks sales, tips ("kefirowe"), costs, history, and cash flow. Let me convert this into a full Next.js web application with the same functionality and dark gold/sepia theme.

I've converted the Chrome extension financial panel into a full Next.js web application. The "Stare Czasy" (Old Times) financial management panel is now a complete web app featuring:

Main Features:

• Dashboard - Overview with KPI cards showing revenue, tips (kefirowe), costs, profit/loss, and cash position
• Sprzedaz (Sales) - Track weekend and event sales with cash/card breakdown
• Kefirowe (Tips) - Manage tip income/expenses outside the fiscal register
• Koszty (Costs) - Six categories: purchases, payroll, utilities, taxes, VAT, and other/transfers
• Historia (History) - Monthly comparison with a visual bar chart
• Kasa (Cash) - Current cash register and bank account balances with obligation tracking

Technical Details:

• Dark sepia/gold theme matching the original extension design
• Polish language interface with PLN currency formatting
• Date range filtering for all data views
• LocalStorage persistence for all data
• Responsive grid layouts for different screen sizes
• Status toggles for paid/unpaid items
• Running balance calculations for tips