Add theme and router config to app

src/App.tsx

@@ -1,26 +1,13 @@
-import React from 'react';
-import logo from './logo.svg';
-import './App.css';
+import { Route, Switch } from 'react-router';
 
-function App() {
+const App = () => {
   return (
-    <div className="App">
-      <header className="App-header">
-        <img src={logo} className="App-logo" alt="logo" />
-        <p>
-          Edit <code>src/App.tsx</code> and save to reload.
-        </p>
-        <a
-          className="App-link"
-          href="https://reactjs.org"
-          target="_blank"
-          rel="noopener noreferrer"
-        >
-          Learn React
-        </a>
-      </header>
-    </div>
+    <Switch>
+      <Route path='/' exact>
+        <div></div>
+      </Route>
+    </Switch>
   );
-}
+};
 
 export default App;