reactjs/react.dev — reverse-engineered prompt

Build me a polished documentation website for React, similar in feel to react.dev. It should be a clean, fast site where visitors can read React docs, move between different documentation sections, and view pages comfortably on desktop and mobile. I want the content to live in simple docs files so it is easy to edit, and changes should show up locally while I’m working.

Please set it up as a modern React website that runs with Yarn and a local dev server at localhost 3000, using Next.js since this is meant to be a real documentation site.

Include the basic project setup, styling, layout, navigation, sample docs pages, and whatever scripts are needed to format, lint, type check, and prepare it for deployment. Keep the writing and structure friendly for contributors, with clear instructions in the README for installing, running locally, testing changes, and contributing. Look up current docs online if you need to.