feat: update UI to glassmorphic design and copper theme

frontend/src/index.tsx

@@ -0,0 +1,9 @@
+import "./index.css";
+import React from "react";
+import ReactDOM from "react-dom/client";
+import { App } from "./App";
+
+const rootEl = document.getElementById("root");
+if (rootEl) {
+  ReactDOM.createRoot(rootEl).render(<App />);
+}