diff --git a/packages/cra-template-typescript/template/src/App.tsx b/packages/cra-template-typescript/template/src/App.tsx
index a53698aab3..c5f36160ae 100644
--- a/packages/cra-template-typescript/template/src/App.tsx
+++ b/packages/cra-template-typescript/template/src/App.tsx
@@ -1,15 +1,19 @@
-import React from 'react';
-import logo from './logo.svg';
-import './App.css';
+import logo from './logo.svg'
+import './App.css'
+import Header from './components/Header'
 
 function App() {
   return (
     <div className="App">
+      <Header />
+
       <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"
@@ -20,7 +24,7 @@ function App() {
         </a>
       </header>
     </div>
-  );
+  )
 }
 
-export default App;
+export default App
diff --git a/packages/cra-template-typescript/template/src/components/Header.tsx b/packages/cra-template-typescript/template/src/components/Header.tsx
new file mode 100644
index 0000000000..c5f36160ae
--- /dev/null
+++ b/packages/cra-template-typescript/template/src/components/Header.tsx
@@ -0,0 +1,30 @@
+import logo from './logo.svg'
+import './App.css'
+import Header from './components/Header'
+
+function App() {
+  return (
+    <div className="App">
+      <Header />
+
+      <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>
+  )
+}
+
+export default App
diff --git a/packages/cra-template-typescript/template/src/hooks/usDarkMode.ts b/packages/cra-template-typescript/template/src/hooks/usDarkMode.ts
new file mode 100644
index 0000000000..82a487fe74
--- /dev/null
+++ b/packages/cra-template-typescript/template/src/hooks/usDarkMode.ts
@@ -0,0 +1,71 @@
+import { useState, useEffect, useCallback } from 'react'
+
+type Theme = 'light' | 'dark'
+
+const STORAGE_KEY = 'theme-preference'
+
+function getSystemTheme(): Theme {
+  return window.matchMedia('(prefers-color-scheme: dark)').matches
+    ? 'dark'
+    : 'light'
+}
+
+function getStoredTheme(): Theme | null {
+  const stored = localStorage.getItem(STORAGE_KEY)
+  if (stored === 'light' || stored === 'dark') {
+    return stored
+  }
+  return null
+}
+
+function applyTheme(theme: Theme) {
+  document.documentElement.setAttribute('data-theme', theme)
+}
+
+export function useDarkMode() {
+  const [theme, setThemeState] = useState<Theme>(() => {
+    const stored = getStoredTheme()
+    return stored ?? getSystemTheme()
+  })
+
+  useEffect(() => {
+    applyTheme(theme)
+    localStorage.setItem(STORAGE_KEY, theme)
+  }, [theme])
+
+  useEffect(() => {
+    const stored = getStoredTheme()
+    if (stored !== null) return
+
+    const mediaQuery = window.matchMedia('(prefers-color-scheme: dark)')
+
+    const handler = (e: MediaQueryListEvent) => {
+      setThemeState(e.matches ? 'dark' : 'light')
+    }
+
+    if (mediaQuery.addEventListener) {
+      mediaQuery.addEventListener('change', handler)
+      return () => mediaQuery.removeEventListener('change', handler)
+    }
+
+    mediaQuery.addListener(handler)
+    return () => mediaQuery.removeListener(handler)
+  }, [])
+
+  const toggleTheme = useCallback(() => {
+    setThemeState(prev => (prev === 'light' ? 'dark' : 'light'))
+  }, [])
+
+  const setTheme = useCallback((theme: Theme) => {
+    setThemeState(theme)
+  }, [])
+
+  return {
+    theme,
+    isDark: theme === 'dark',
+    toggleTheme,
+    setTheme
+  }
+}
+
+export default useDarkMode
diff --git a/packages/cra-template-typescript/template/src/hooks/useDarkMode.ts b/packages/cra-template-typescript/template/src/hooks/useDarkMode.ts
new file mode 100644
index 0000000000..872b1e4ad5
--- /dev/null
+++ b/packages/cra-template-typescript/template/src/hooks/useDarkMode.ts
@@ -0,0 +1,78 @@
+import { useEffect, useState } from 'react'
+
+type Theme = 'light' | 'dark'
+
+const STORAGE_KEY = 'theme'
+const MEDIA_QUERY = '(prefers-color-scheme: dark)'
+
+function getStoredTheme(): Theme | null {
+  try {
+    const value = window.localStorage.getItem(STORAGE_KEY)
+    return value === 'light' || value === 'dark' ? value : null
+  } catch {
+    return null
+  }
+}
+
+function getSystemTheme(): Theme {
+  return window.matchMedia(MEDIA_QUERY).matches ? 'dark' : 'light'
+}
+
+export function useDarkMode() {
+  const [theme, setThemeState] = useState<Theme>(() => {
+    if (typeof window === 'undefined') {
+      return 'light'
+    }
+
+    return getStoredTheme() ?? getSystemTheme()
+  })
+
+  useEffect(() => {
+    document.documentElement.setAttribute('data-theme', theme)
+
+    try {
+      window.localStorage.setItem(STORAGE_KEY, theme)
+    } catch {
+      // ignore storage errors
+    }
+  }, [theme])
+
+  useEffect(() => {
+    if (typeof window === 'undefined') {
+      return
+    }
+
+    const mediaQuery = window.matchMedia(MEDIA_QUERY)
+
+    const handleChange = (event: MediaQueryListEvent) => {
+      const storedTheme = getStoredTheme()
+
+      if (!storedTheme) {
+        setThemeState(event.matches ? 'dark' : 'light')
+      }
+    }
+
+    if (typeof mediaQuery.addEventListener === 'function') {
+      mediaQuery.addEventListener('change', handleChange)
+      return () => mediaQuery.removeEventListener('change', handleChange)
+    }
+
+    mediaQuery.addListener(handleChange)
+    return () => mediaQuery.removeListener(handleChange)
+  }, [])
+
+  const setTheme = (nextTheme: Theme) => {
+    setThemeState(nextTheme)
+  }
+
+  const toggleTheme = () => {
+    setThemeState(prev => (prev === 'light' ? 'dark' : 'light'))
+  }
+
+  return {
+    theme,
+    isDark: theme === 'dark',
+    setTheme,
+    toggleTheme
+  }
+}
diff --git a/packages/cra-template-typescript/template/src/index.css b/packages/cra-template-typescript/template/src/index.css
index ec2585e8c0..a9f17f065c 100644
--- a/packages/cra-template-typescript/template/src/index.css
+++ b/packages/cra-template-typescript/template/src/index.css
@@ -1,13 +1,73 @@
 body {
   margin: 0;
-  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Oxygen',
-    'Ubuntu', 'Cantarell', 'Fira Sans', 'Droid Sans', 'Helvetica Neue',
-    sans-serif;
+  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;
+
+  background-color: #ffffff;
+  color: #333333;
+
+  transition: background-color 0.3s ease, color 0.3s ease;
 }
 
 code {
-  font-family: source-code-pro, Menlo, Monaco, Consolas, 'Courier New',
-    monospace;
+  font-family: source-code-pro, Menlo, Monaco, Consolas,
+    'Courier New', monospace;
+}
+
+body[data-theme='dark'] {
+  background-color: #1a1a2e;
+  color: #eaeaea;
+}
+
+.app-header {
+  padding: 12px 24px;
+  background-color: #f8f9fa;
+  border-bottom: 1px solid #e9ecef;
+  transition: background-color 0.3s ease;
+}
+
+body[data-theme='dark'] .app-header {
+  background-color: #16213e;
+}
+
+.header-content {
+  display: flex;
+  justify-content: space-between;
+  align-items: center;
+}
+
+.header-title {
+  font-size: 1.25rem;
+  font-weight: 600;
+}
+
+.theme-toggle {
+  background: none;
+  border: 2px solid #dee2e6;
+  border-radius: 50%;
+  width: 40px;
+  height: 40px;
+
+  cursor: pointer;
+
+  font-size: 1.1rem;
+
+  display: flex;
+  align-items: center;
+  justify-content: center;
+
+  transition: border-color 0.2s ease, transform 0.2s ease;
+}
+
+.theme-toggle:hover {
+  border-color: #61dafb;
+  transform: scale(1.05);
+}
+
+body[data-theme='dark'] .theme-toggle {
+  border-color: #495057;
 }