feat(auth0) add Loading component

auth0-blog/app/app.jsx

@@ -1,10 +1,16 @@
 import React from 'react';
+import { useAuth0 } from '@auth0/auth0-react';
 
 import NavBar from "./components/nav-bar";
+import Loading from "./components/loading";
 import Home from './pages/home';
 export default function App() {
+    const { isLoading } = useAuth0();
+    if (isLoading) {
+	return <Loading />;
+    }
     return (
-	<div id="app" className="d-flex flex-column h-100">
+	<div>
 	    <NavBar />
 	    <div>
 		<h1>Auth0 with React.js</h1>

auth0-blog/app/components/loading.jsx

@@ -0,0 +1,11 @@
+import React from "react";
+const loadingImg =
+  "https://cdn.auth0.com/blog/auth0-react-sample/assets/loading.svg";
+
+const Loading = () => (
+  <div className="spinner">
+    <img src={loadingImg} alt="Loading..." />
+  </div>
+);
+
+export default Loading;

auth0-blog/app/components/login-button.jsx

@@ -5,7 +5,6 @@ const LoginButton = () => {
   const { loginWithRedirect } = useAuth0();
   return (
     <button
-      className="btn btn-primary btn-block"
       onClick={() => loginWithRedirect()}
     >
       Log In

auth0-blog/app/components/logout-button.jsx

@@ -5,7 +5,6 @@ const LogoutButton = () => {
   const { logout } = useAuth0();
   return (
     <button
-      className="btn btn-danger btn-block"
       onClick={() =>
         logout({
           returnTo: window.location.origin,