add some build optimizations

package.json

@@ -36,6 +36,7 @@
   "scripts": {
     "start": "react-scripts start",
     "build": "react-scripts build",
+    "build-opt": "react-scripts --max_old_space_size=4096 build",
     "test": "react-scripts test",
     "eject": "react-scripts eject"
   },

src/App.js

@@ -1,7 +1,6 @@
 import React, { Component } from 'react';
 import Home from './components/Home'
 import logo from './logo.svg';
-import './App.css';
 
 class App extends Component {
   render() {

src/components/ChatRoom.js

@@ -16,8 +16,6 @@ import ChatHeader from './ChatHeader';
 import Userlist from './Userlist';
 import { uploadFileAndSend } from '../utils/ipfs';
 
-import 'emoji-mart/css/emoji-mart.css';
-
 class WhoIsTyping extends PureComponent {
 
   whoIsTyping() {

src/index.js

@@ -1,6 +1,5 @@
 import React from 'react';
 import ReactDOM from 'react-dom';
-import './index.css';
 import App from './App';
 import * as serviceWorker from './serviceWorker';