SurajBhari/Login-System-with-Python-Flask-and-Sqlite ? reverse-engineered prompt

Build me a simple login and registration web app with Flask and SQLite for beginners.

I want users to be able to create an account, log in, and log out, with the form data checked properly for things like username, email, and password. Please make the pages look clean with basic HTML and CSS, and use Flask templates for the UI. It should store user data in SQLite, use sessions to keep users signed in, and have the main routes wired up so the flow feels complete and easy to use.

Please also include a small test script or basic checks so I can verify the app works before running it. If anything is missing or unclear, look up current Flask and SQLite docs online and fill in the gaps in a practical way.