remove stuff

src/App.js

@@ -1,25 +1,10 @@
 import React, { Component } from 'react';
-import logo from './logo.svg';
-import './App.css';
 
 class App extends Component {
   render() {
     return (
-      <div className="App">
-        <header className="App-header">
-          <img src={logo} className="App-logo" alt="logo" />
-          <p>
-            Edit <code>src/App.js</code> and save to reload.
-          </p>
-          <a
-            className="App-link"
-            href="https://reactjs.org"
-            target="_blank"
-            rel="noopener noreferrer"
-          >
-            Learn React
-          </a>
-        </header>
+      <div>
+        Hello world
       </div>
     );
   }

src/index.css

@@ -8,7 +8,3 @@ body {
   -moz-osx-font-smoothing: grayscale;
 }
 
-code {
-  font-family: source-code-pro, Menlo, Monaco, Consolas, "Courier New",
-    monospace;
-}

src/index.js

@@ -2,11 +2,5 @@ import React from 'react';
 import ReactDOM from 'react-dom';
 import './index.css';
 import App from './App';
-import * as serviceWorker from './serviceWorker';
 
 ReactDOM.render(<App />, document.getElementById('root'));
-
-// If you want your app to work offline and load faster, you can change
-// unregister() to register() below. Note this comes with some pitfalls.
-// Learn more about service workers: http://bit.ly/CRA-PWA
-serviceWorker.unregister();