How does it know a file has changed? It constantly reloads it? For a less magical tool, there's https://www.npmjs.com/package/instant-server https://www.npmjs.

How does it know a file has changed? It constantly reloads it? For a less magical tool, there's https://www.npmjs.com/package/instant-server https://www.npmjs.com/package/instant-server, which acts a simple HTTP server, but reloads your CSS whenever it changes without refreshing (it also refreshes on JS or HTML changes, but nevermind).