Blurry result depending on server the app is served with

When I server the app from this repo with live Server I get a neat

But If I serve it with node const server = http.createServer((req, res) => {...} code in the index.js file, I get this blurred result.

I tried also with an static server with the same result (commented in the index.js codein the repo)

var file = new(static.Server)(__dirname);

http.createServer(function (req, res) {
  file.serve(req, res);
}).listen(8000);

In the screenshots might not be that clear, but when the app runs in the browser the difference is huge. I think there should be some step in the serving process that I am missing.

Thanks in advanced for any idea.