init commit,

03_source/mobile_baseline.bak/src/main.tsx

@@ -0,0 +1,14 @@
+import React from 'react';
+import ReactDOM from 'react-dom/client';
+import App from './App';
+import * as serviceWorker from './serviceWorker';
+
+ReactDOM.createRoot(document.getElementById('root') as HTMLElement).render(
+  <React.StrictMode>
+    <App />
+  </React.StrictMode>
+);
+// 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: https://bit.ly/CRA-PWA
+serviceWorker.register();