diff --git a/index.html b/index.html
index 28cedfe..bdb7567 100644
--- a/index.html
+++ b/index.html
@@ -1,4 +1,4 @@
-<!DOCTYPE html>
+<!doctype html>
 <html lang="en">
   <head>
     <meta charset="UTF-8" />
diff --git a/src/App.tsx b/src/App.tsx
index 24c8eeb..635e51c 100644
--- a/src/App.tsx
+++ b/src/App.tsx
@@ -1,11 +1,24 @@
-import React from 'react'
+import { useState } from 'react'
 
 function App() {
+  const [count, setCount] = useState(0)
+
   return (
-    <div className="min-h-screen bg-gray-100">
-      <h1 className="text-3xl font-bold text-center pt-10">
-        Hello Vite + React + Tailwind!
-      </h1>
+    <div className="min-h-screen bg-gray-50 flex items-center justify-center">
+      <div className="text-center">
+        <h1 className="text-4xl font-bold text-gray-900 mb-8">Vite + React + Tailwind</h1>
+        <div className="bg-white p-8 rounded-lg shadow-lg">
+          <button
+            className="bg-blue-500 hover:bg-blue-700 text-white font-bold py-2 px-4 rounded"
+            onClick={() => setCount((count) => count + 1)}
+          >
+            count is {count}
+          </button>
+          <p className="mt-4 text-gray-600">
+            Edit <code className="bg-gray-100 px-2 py-1 rounded">src/App.tsx</code> and save to test HMR
+          </p>
+        </div>
+      </div>
     </div>
   )
 }
diff --git a/src/index.css b/src/index.css
index bd6213e..4bf1c5d 100644
--- a/src/index.css
+++ b/src/index.css
@@ -1,3 +1,17 @@
 @tailwind base;
 @tailwind components;
-@tailwind utilities;
\ No newline at end of file
+@tailwind utilities;
+
+body {
+  margin: 0;
+  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Oxygen',
+    'Ubuntu', 'Cantarell', 'Fira Sans', 'Droid Sans', 'Helvetica Neue',
+    sans-serif;
+  -webkit-font-smoothing: antialiased;
+  -moz-osx-font-smoothing: grayscale;
+}
+
+code {
+  font-family: source-code-pro, Menlo, Monaco, Consolas, 'Courier New',
+    monospace;
+}
\ No newline at end of file
diff --git a/tsconfig.json b/tsconfig.json
index 4db7363..9e275b2 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -3,11 +3,15 @@
     "target": "ES2020",    "useDefineForClassFields": true,
     "lib": ["ES2020", "DOM", "DOM.Iterable"],
     "module": "ESNext",    "skipLibCheck": true,
+
+    /* Bundler mode */
     "moduleResolution": "bundler",    "allowImportingTsExtensions": true,
     "resolveJsonModule": true,
     "isolatedModules": true,
     "noEmit": true,
-    "jsx": "react-jsx",    "strict": true,
+    "jsx": "react-jsx",
+    /* Linting */
+    "strict": true,
     "noUnusedLocals": true,
     "noUnusedParameters": true,
     "noFallthroughCasesInSwitch": true
diff --git a/vite.config.ts b/vite.config.ts
index 3e34260..2dea53a 100644
--- a/vite.config.ts
+++ b/vite.config.ts
@@ -1,6 +1,7 @@
 import { defineConfig } from 'vite'
 import react from '@vitejs/plugin-react'
 
+// https://vitejs.dev/config/
 export default defineConfig({
   plugins: [react()],
 })
\ No newline at end of file
