backlesshub-max/maa-ai ? reverse-engineered prompt

Build me a simple web app with a clean landing page and a working backend so I can use it from the browser.

I already have a basic setup with an HTML page, styles, a main app file, a backend folder, and a data folder, so please wire everything together into something usable and polished. I want the page to look modern, respond well on mobile, and feel straightforward for a normal person to use. The backend should handle the main app logic and make the frontend actually do something useful, with data saved and loaded from the local data folder if needed.

If anything is unclear, check the current docs online and make the simplest sensible choice. Please also make sure the app runs cleanly from start to finish, with any missing glue code filled in and the whole thing set up so I can launch it and try it right away.