diff --git a/javascript/dwa-starter-vanillajs-vite/components.js b/javascript/dwa-starter-vanillajs-vite/components.js
index bce8bfec..ef0e46e8 100644
--- a/javascript/dwa-starter-vanillajs-vite/components.js
+++ b/javascript/dwa-starter-vanillajs-vite/components.js
@@ -1,57 +1,71 @@
-// components.js
-function AboutPage() {
-    // Create the main container
+// Create the theme toggle button
+function ThemeToggleButton() {
+    const button = document.createElement('button');
+    button.setAttribute('aria-label', 'Toggle dark mode');
+    button.textContent = 'Toggle Theme';
+    button.classList.add('p-2', 'rounded', 'border', 'bg-gray-200', 'dark:bg-gray-700');
+  
+    // Add click event to toggle dark mode
+    button.addEventListener('click', () => {
+      document.documentElement.classList.toggle('dark');
+      const isDarkMode = document.documentElement.classList.contains('dark');
+      localStorage.setItem('theme', isDarkMode ? 'dark' : 'light');
+    });
+  
+    return button;
+  }
+  
+  // Append the theme toggle button to the page
+  function addThemeToggleToPage() {
+    const toggleButton = ThemeToggleButton();
+    document.body.prepend(toggleButton); // Add the toggle button to the body
+  }
+  
+  // Create About page
+  function AboutPage() {
     const container = document.createElement('div');
     container.classList.add('space-y-4', 'p-6', 'text-center');
-  
-    // Create the main title
+    
     const title = document.createElement('h1');
     title.textContent = 'DWA Starter Vanilla';
     title.classList.add('text-3xl', 'font-bold', 'mb-4');
-  
-    // Create the first paragraph
+    
     const para1 = document.createElement('p');
     para1.textContent = "Decentralized Web App: it's a Web5 Progressive Web App.";
     para1.classList.add('text-lg');
-  
-    // Create the subtitle
+    
     const subtitle = document.createElement('h2');
     subtitle.textContent = 'Why PWA?';
     subtitle.classList.add('text-2xl', 'font-semibold', 'mt-4');
-  
-    // Create the second paragraph
+    
     const para2 = document.createElement('p');
     para2.textContent = 'It\'s a perfect match with Web5 DWNs since a PWA can work offline and DWN has a synced local storage.';
     para2.classList.add('text-lg');
-  
-    // Append elements to the container
+    
     container.appendChild(title);
     container.appendChild(para1);
     container.appendChild(subtitle);
     container.appendChild(para2);
-  
-    // Return the container element
+    
     return container;
   }
   
-export function Home() {
+  export function Home() {
     document.getElementById('app').innerHTML = `<h1>Home</h1>`;
-}
-
-export function About() {
+  }
+  
+  export function About() {
     const app = document.getElementById('app');
-    app.innerHTML = ''; // Clear the current content
-
-    // Create and append the About page
-    const aboutPage = AboutPage(); // Call the AboutPage function to get the component
+    app.innerHTML = '';
+    const aboutPage = AboutPage();
     app.appendChild(aboutPage);
-}
-
-export function Settings() {
+  }
+  
+  export function Settings() {
     document.getElementById('app').innerHTML = `<h1>Settings</h1>`;
-}
-
-export function NotFound() {
+  }
+  
+  export function NotFound() {
     document.getElementById('app').innerHTML = `<h1>404 - Page Not Found</h1>`;
-}
-
+  }
+  
\ No newline at end of file
diff --git a/javascript/dwa-starter-vanillajs-vite/main.js b/javascript/dwa-starter-vanillajs-vite/main.js
index acaf8102..3ea209ae 100644
--- a/javascript/dwa-starter-vanillajs-vite/main.js
+++ b/javascript/dwa-starter-vanillajs-vite/main.js
@@ -1,37 +1,49 @@
-// main.js
+// Function to check system preference and localStorage for theme preference
+function applyTheme() {
+    const prefersDarkScheme = window.matchMedia("(prefers-color-scheme: dark)").matches;
+    const currentTheme = localStorage.getItem("theme") || (prefersDarkScheme ? "dark" : "light");
 
-import { Home, About, Settings, NotFound } from './components.js';
+    // Toggle dark mode based on the stored or system preference
+    document.documentElement.classList.toggle('dark', currentTheme === 'dark');
+}
 
-// Define routes and their corresponding components
-const routes = {
-    '/': Home,
-    '/about': About,
-    '/settings': Settings,
-};
+// Function to add the theme toggle functionality to the page
+function addThemeToggleToPage() {
+    const toggleButton = document.querySelector("#theme-toggle");
 
-// Function to handle navigation
-function navigateTo(url) {
-    history.pushState(null, null, url);
-    router();
-}
+    // Listen for the toggle button click
+    toggleButton.addEventListener("click", () => {
+        const isDarkMode = document.documentElement.classList.contains('dark');
+        const newTheme = isDarkMode ? 'light' : 'dark';
 
-// Router function to render components based on the current URL
-function router() {
-    const path = window.location.pathname;
-    const route = routes[path] || NotFound;
-    route();
+        // Toggle the theme and save to localStorage
+        document.documentElement.classList.toggle('dark', newTheme === 'dark');
+        localStorage.setItem("theme", newTheme);
+    });
 }
 
-// Event delegation for link clicks
-document.addEventListener('click', (e) => {
-    if (e.target.matches('[data-link]')) {
-        e.preventDefault();
-        navigateTo(e.target.href);
-    }
+// Apply the theme on page load
+window.addEventListener("DOMContentLoaded", () => {
+    applyTheme();
+    addThemeToggleToPage();
 });
 
-// Listen to popstate event (back/forward navigation)
-window.addEventListener('popstate', router);
+// Router logic
+const routes = {
+    '/': () => `<h1>Home</h1>`,
+    '/about': () => `<h1>DWA Starter Vanilla</h1>`,
+    '/settings': () => `<h1>Settings</h1>`,
+    '*': () => `<h1>404 - Page Not Found</h1>`,
+};
+
+function handleRoute() {
+    const path = window.location.pathname;
+    const route = routes[path] || routes['*'];
+    document.getElementById('app').innerHTML = route();
+}
+
+// Handle back/forward navigation
+window.addEventListener('popstate', handleRoute);
 
-// Initial call to router to render the correct component on page load
-document.addEventListener('DOMContentLoaded', router);
+// Initial page load
+handleRoute();
diff --git a/javascript/dwa-starter-vanillajs-vite/style.css b/javascript/dwa-starter-vanillajs-vite/style.css
index 9e71cd2a..ad298177 100644
--- a/javascript/dwa-starter-vanillajs-vite/style.css
+++ b/javascript/dwa-starter-vanillajs-vite/style.css
@@ -1,4 +1,3 @@
-/* styles.css */
 @tailwind base;
 @tailwind components;
 @tailwind utilities;
@@ -38,3 +37,16 @@ nav a:hover {
 #app {
   padding: 20px;
 }
+
+/* Dark mode styles */
+.dark nav {
+  background-color: #222;
+}
+
+.dark nav a {
+  color: #bbb;
+}
+
+.dark nav a:hover {
+  background-color: #444;
+}
diff --git a/javascript/dwa-starter-vanillajs-vite/tailwind.config.js b/javascript/dwa-starter-vanillajs-vite/tailwind.config.js
index 7172b0e3..95de6492 100644
--- a/javascript/dwa-starter-vanillajs-vite/tailwind.config.js
+++ b/javascript/dwa-starter-vanillajs-vite/tailwind.config.js
@@ -1,5 +1,6 @@
 /** @type {import('tailwindcss').Config} */
 module.exports = {
+  darkMode: 'class',
   content: [
     "./index.html",
     "./components.js",
diff --git a/javascript/dwa-starter-vanillajs-vite/tests/main.spec.js b/javascript/dwa-starter-vanillajs-vite/tests/main.spec.js
index 97b26262..86073fc2 100644
--- a/javascript/dwa-starter-vanillajs-vite/tests/main.spec.js
+++ b/javascript/dwa-starter-vanillajs-vite/tests/main.spec.js
@@ -1,26 +1,72 @@
-// tests/router.spec.js
 import { test, expect } from '@playwright/test';
 
 test.describe('Vanilla Router', () => {
-    // Before all tests, start a local server if necessary
-
     test('should navigate to Home', async ({ page }) => {
-        await page.goto('/');
+        await page.goto('http://localhost:5173/');
         expect(await page.textContent('h1')).toBe('Home');
     });
 
     test('should navigate to About', async ({ page }) => {
-        await page.goto('/about');
-        expect(await page.textContent('h1')).toBe('DWA Starter Vanilla'); 
+        await page.goto('http://localhost:5173/about');
+        expect(await page.textContent('h1')).toBe('DWA Starter Vanilla');
     });
 
     test('should navigate to Settings', async ({ page }) => {
-        await page.goto('/settings');
+        await page.goto('http://localhost:5173/settings');
         expect(await page.textContent('h1')).toBe('Settings');
     });
 
     test('should show Not Found for undefined routes', async ({ page }) => {
-        await page.goto('/undefined-route');
+        await page.goto('http://localhost:5173/undefined-route');
         expect(await page.textContent('h1')).toBe('404 - Page Not Found');
     });
 });
+
+test.describe('Theme Toggle Functionality', () => {
+    test('should toggle dark mode and remember preference', async ({ page }) => {
+        await page.goto('http://localhost:5173/');
+        
+        // Check initial state
+        const initialIsDarkMode = await page.evaluate(() => document.documentElement.classList.contains('dark'));
+        
+        // Toggle the theme
+        await page.click('#theme-toggle');
+        
+        // Verify that the theme was toggled
+        const isDarkModeAfterToggle = await page.evaluate(() => document.documentElement.classList.contains('dark'));
+        expect(isDarkModeAfterToggle).toBe(!initialIsDarkMode);
+        
+        // Reload the page to check if preference is remembered
+        await page.reload();
+        const isDarkModeAfterReload = await page.evaluate(() => document.documentElement.classList.contains('dark'));
+        expect(isDarkModeAfterReload).toBe(isDarkModeAfterToggle);
+    });
+
+    test('should load with correct theme based on system preference when no localStorage is set', async ({ page }) => {
+        // Clear localStorage
+        await page.evaluate(() => localStorage.removeItem('theme'));
+
+        await page.goto('http://localhost:5173/');
+
+        // Get system preference
+        const prefersDarkMode = await page.evaluate(() => window.matchMedia('(prefers-color-scheme: dark)').matches);
+
+        // Check if the page loads with the correct theme based on system preference
+        const isDarkMode = await page.evaluate(() => document.documentElement.classList.contains('dark'));
+        expect(isDarkMode).toBe(prefersDarkMode);
+    });
+
+    test('should persist theme across different routes', async ({ page }) => {
+        await page.goto('http://localhost:5173/');
+        
+        // Toggle to dark mode
+        await page.click('#theme-toggle');
+        const isDarkMode = await page.evaluate(() => document.documentElement.classList.contains('dark'));
+        expect(isDarkMode).toBe(true);
+
+        // Navigate to a different route
+        await page.goto('http://localhost:5173/about');
+        const isDarkModeOnNewRoute = await page.evaluate(() => document.documentElement.classList.contains('dark'));
+        expect(isDarkModeOnNewRoute).toBe(true);
+    });
+});