FerreiraArth/taskSystem-js ? reverse-engineered prompt

Build me a simple task manager web app in JavaScript.

I want to be able to add tasks, mark them as done, edit them, and delete them. It should feel clean and easy to use, with a basic layout that works well in the browser. Please keep it all in one small project and make sure the main page actually works when I open it in the browser.

If you need to, look up current docs online, but keep the solution simple and focused on practicing JavaScript features.