I already have a collection of self-contained HTML pages, each one presenting a different calculation formula. I now need those pages bundled into a single, polished mobile application that runs natively on both iOS and Android. Core requirements • All existing HTML files should load inside the app (WebView is fine) and be reachable through a clean side-drawer hamburger menu. • The overall look must feel up-to-date—think smooth transitions, modern fonts, dark-mode readiness, and responsive layouts that make every formula page easy to read on any screen size. • Access to the content must sit behind a monthly subscription. Integrate in-app purchase flows for Apple App Store and Google Play, handle payment validation, and block content automatically when a renewal fails. No tier levels are needed right now—just one plan, billed monthly. • I will supply the HTML files; you package, style, and wire them to the navigation and subscription logic. Deliverables 1. iOS and Android builds ready for store submission, plus full source code. 2. A brief setup document explaining how to add or update an HTML file in the future. 3. Test accounts or sandbox instructions showing the monthly payment flow working end-to-end. Once I can install the app, swipe open the menu, tap through every formula page, and confirm that the subscription wall behaves correctly, the job is complete.