diff --git a/package-lock.json b/package-lock.json
index a31296a..3dc0ea2 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -917,7 +917,6 @@
       "integrity": "sha512-5gTmgEY/sqK6gFXLIsQNH19lWb4ebPDLA4SdLP7dsWkIXHWlG66oPuVvXSGFPppYZz8ZDZq0dYYrbHfBCVUb1Q==",
       "dev": true,
       "license": "MIT",
-      "peer": true,
       "engines": {
         "node": ">=12"
       },
diff --git a/src/components/Sidebar.js b/src/components/Sidebar.js
new file mode 100644
index 0000000..19e3a21
--- /dev/null
+++ b/src/components/Sidebar.js
@@ -0,0 +1,48 @@
+export function createSidebar(pages, currentPage) {
+  const sidebar = document.createElement('aside');
+  sidebar.className = 'sidebar';
+  sidebar.id = 'sidebar';
+
+  const sidebarHeader = document.createElement('div');
+  sidebarHeader.className = 'sidebar-header';
+  sidebarHeader.innerHTML = /*html*/`
+    <h2>Doli App</h2>
+    <button class="sidebar-toggle" id="sidebar-toggle" aria-label="Toggle sidebar">
+      <span class="toggle-icon">☰</span>
+    </button>
+  `;
+
+  const nav = document.createElement('nav');
+  nav.className = 'sidebar-nav';
+
+  const navList = document.createElement('ul');
+  navList.className = 'sidebar-menu';
+
+  pages.forEach(page => {
+    const listItem = document.createElement('li');
+    const link = document.createElement('a');
+    link.href = `#${page.route}`;
+    link.className = 'sidebar-link';
+    if (page.route === currentPage) {
+      link.classList.add('active');
+    }
+    link.innerHTML = /*html*/`
+      <span class="sidebar-icon">${page.icon || '📄'}</span>
+      <span class="sidebar-text">${page.name}</span>
+    `;
+    listItem.appendChild(link);
+    navList.appendChild(listItem);
+  });
+
+  nav.appendChild(navList);
+  sidebar.appendChild(sidebarHeader);
+  sidebar.appendChild(nav);
+
+  // Toggle functionality
+  const toggleBtn = sidebarHeader.querySelector('#sidebar-toggle');
+  toggleBtn.addEventListener('click', () => {
+    sidebar.classList.toggle('collapsed');
+  });
+
+  return sidebar;
+}
diff --git a/src/pages/pagesRegistry.js b/src/pages/pagesRegistry.js
new file mode 100644
index 0000000..ac5bd89
--- /dev/null
+++ b/src/pages/pagesRegistry.js
@@ -0,0 +1,46 @@
+// Registry of all pages available in the application
+export const pagesRegistry = [
+  {
+    route: 'dashboard',
+    name: 'Dashboard',
+    icon: '🏠',
+    requiresAuth: true
+  },
+  {
+    route: 'test',
+    name: 'Test Page',
+    icon: '🧪',
+    requiresAuth: true
+  },
+  {
+    route: 'invoices',
+    name: 'Facturas',
+    icon: '📄',
+    requiresAuth: true
+  },
+  {
+    route: 'clients',
+    name: 'Clientes',
+    icon: '👥',
+    requiresAuth: true
+  },
+  {
+    route: 'settings',
+    name: 'Configuración',
+    icon: '⚙️',
+    requiresAuth: true
+  }
+];
+
+// Get pages that the user can access
+export function getAvailablePages(isAuthenticated) {
+  if (!isAuthenticated) {
+    return [];
+  }
+  return pagesRegistry.filter(page => !page.requiresAuth || isAuthenticated);
+}
+
+// Get page by route
+export function getPageByRoute(route) {
+  return pagesRegistry.find(page => page.route === route);
+}
diff --git a/src/pages/test.js b/src/pages/test.js
new file mode 100644
index 0000000..890d52a
--- /dev/null
+++ b/src/pages/test.js
@@ -0,0 +1,19 @@
+export function renderTestPage() {
+  const container = document.createElement('div');
+  container.className = 'test-page';
+
+  container.innerHTML = /*html*/`
+    <h1>Test Page</h1>
+    <p>This is a test page to verify sidebar navigation functionality.</p>
+    <div class="test-content">
+      <p>The sidebar should be visible and allow navigation between different pages.</p>
+      <button id="test-btn" class="test-button">Test Button</button>
+    </div>
+  `;
+
+  container.querySelector('#test-btn').addEventListener('click', () => {
+    alert('Test button clicked!');
+  });
+
+  return container;
+}
diff --git a/src/router.js b/src/router.js
index a565ba9..6ecda04 100644
--- a/src/router.js
+++ b/src/router.js
@@ -1,12 +1,16 @@
 import { auth } from './services/auth.js';
 import { renderLoginPage } from './pages/LoginPage.js';
 import { renderDashboard } from './pages/DashboardPage.js';
+import { renderTestPage } from './pages/test.js';
+import { createSidebar } from './components/Sidebar.js';
+import { getAvailablePages } from './pages/pagesRegistry.js';
 
 export function initRouter() {
   const app = document.querySelector('#app');
 
   function navigate() {
     const hash = window.location.hash || '#login';
+    const route = hash.substring(1); // Remove the # symbol
 
     if (!auth.checkAuth() && hash !== '#login') {
       window.location.hash = '#login';
@@ -15,17 +19,48 @@ export function initRouter() {
 
     app.innerHTML = '';
 
-    switch (hash) {
-      case '#login':
-        app.appendChild(renderLoginPage(() => {
+    // For authenticated routes, add sidebar and main content wrapper
+    if (auth.checkAuth() && hash !== '#login') {
+      const layout = document.createElement('div');
+      layout.className = 'app-layout';
+
+      // Create sidebar
+      const pages = getAvailablePages(true);
+      const sidebar = createSidebar(pages, route);
+      
+      // Create main content area
+      const mainContent = document.createElement('main');
+      mainContent.className = 'main-content';
+
+      let pageContent;
+      switch (hash) {
+        case '#dashboard':
+          pageContent = renderDashboard();
+          break;
+        case '#test':
+          pageContent = renderTestPage();
+          break;
+        default:
+          // For unregistered routes, redirect to dashboard
           window.location.hash = '#dashboard';
-        }));
-        break;
-      case '#dashboard':
-        app.appendChild(renderDashboard());
-        break;
-      default:
-        window.location.hash = '#login';
+          return;
+      }
+
+      mainContent.appendChild(pageContent);
+      layout.appendChild(sidebar);
+      layout.appendChild(mainContent);
+      app.appendChild(layout);
+    } else {
+      // For login page, no sidebar
+      switch (hash) {
+        case '#login':
+          app.appendChild(renderLoginPage(() => {
+            window.location.hash = '#dashboard';
+          }));
+          break;
+        default:
+          window.location.hash = '#login';
+      }
     }
   }
 
diff --git a/src/style.css b/src/style.css
index 16aad82..17b2db5 100644
--- a/src/style.css
+++ b/src/style.css
@@ -37,8 +37,6 @@ a:hover {
 
 body {
   margin: 0;
-  display: flex;
-  place-items: center;
   min-width: 320px;
   min-height: 100vh;
 }
@@ -49,10 +47,8 @@ h1 {
 }
 
 #app {
-  max-width: 1280px;
-  margin: 0 auto;
-  padding: 2rem;
-  text-align: center;
+  width: 100%;
+  min-height: 100vh;
 }
 
 .logo {
@@ -283,3 +279,198 @@ button:focus-visible {
 .card-stat.negative .card-stat-value {
   color: var(--danger);
 }
+
+/* App Layout with Sidebar */
+.app-layout {
+  display: flex;
+  min-height: 100vh;
+  width: 100%;
+}
+
+/* Sidebar Styles */
+.sidebar {
+  width: 250px;
+  background-color: var(--card-bg);
+  border-right: 1px solid var(--border-color);
+  display: flex;
+  flex-direction: column;
+  transition: width 0.3s ease, transform 0.3s ease;
+  position: relative;
+  z-index: 100;
+}
+
+.sidebar-header {
+  padding: 1.5rem 1rem;
+  border-bottom: 1px solid var(--border-color);
+  display: flex;
+  justify-content: space-between;
+  align-items: center;
+}
+
+.sidebar-header h2 {
+  margin: 0;
+  font-size: 1.5rem;
+  color: var(--text-primary);
+  white-space: nowrap;
+  overflow: hidden;
+  text-overflow: ellipsis;
+}
+
+.sidebar-toggle {
+  background: transparent;
+  border: none;
+  cursor: pointer;
+  padding: 0.5rem;
+  color: var(--text-secondary);
+  font-size: 1.25rem;
+  border-radius: 4px;
+  transition: background-color 0.2s;
+}
+
+.sidebar-toggle:hover {
+  background-color: var(--border-color);
+  border-color: transparent;
+}
+
+.sidebar-nav {
+  flex: 1;
+  overflow-y: auto;
+  padding: 1rem 0;
+}
+
+.sidebar-menu {
+  list-style: none;
+  margin: 0;
+  padding: 0;
+}
+
+.sidebar-menu li {
+  margin: 0;
+}
+
+.sidebar-link {
+  display: flex;
+  align-items: center;
+  padding: 0.75rem 1rem;
+  color: var(--text-secondary);
+  text-decoration: none;
+  transition: background-color 0.2s, color 0.2s;
+  cursor: pointer;
+}
+
+.sidebar-link:hover {
+  background-color: var(--border-color);
+  color: var(--text-primary);
+}
+
+.sidebar-link.active {
+  background-color: rgba(37, 99, 235, 0.1);
+  color: var(--primary);
+  border-left: 3px solid var(--primary);
+}
+
+.sidebar-icon {
+  font-size: 1.25rem;
+  margin-right: 0.75rem;
+  min-width: 1.5rem;
+  text-align: center;
+}
+
+.sidebar-text {
+  white-space: nowrap;
+  overflow: hidden;
+  text-overflow: ellipsis;
+}
+
+/* Collapsed Sidebar State */
+.sidebar.collapsed {
+  width: 70px;
+}
+
+.sidebar.collapsed .sidebar-header h2,
+.sidebar.collapsed .sidebar-text {
+  opacity: 0;
+  width: 0;
+  overflow: hidden;
+}
+
+.sidebar.collapsed .sidebar-icon {
+  margin-right: 0;
+}
+
+/* Main Content Area */
+.main-content {
+  flex: 1;
+  overflow-y: auto;
+  background-color: #f8fafc;
+}
+
+.main-content > div {
+  max-width: 1280px;
+  margin: 0 auto;
+  padding: 2rem;
+}
+
+/* Responsive Design */
+@media (max-width: 768px) {
+  .sidebar {
+    position: fixed;
+    left: 0;
+    top: 0;
+    bottom: 0;
+    z-index: 1000;
+    transform: translateX(0);
+  }
+
+  .sidebar.collapsed {
+    transform: translateX(-100%);
+    width: 250px;
+  }
+
+  .main-content {
+    margin-left: 0;
+  }
+}
+
+/* Test Page Styles */
+.test-page {
+  padding: 2rem;
+}
+
+.test-page h1 {
+  color: var(--text-primary);
+  margin-bottom: 1rem;
+  font-size: 2rem;
+}
+
+.test-content {
+  background: var(--card-bg);
+  padding: 2rem;
+  border-radius: 12px;
+  border: 1px solid var(--border-color);
+  margin-top: 1rem;
+}
+
+.test-button {
+  background-color: var(--success);
+  color: white;
+  padding: 0.5rem 1rem;
+  border: none;
+  border-radius: 6px;
+  cursor: pointer;
+  margin-top: 1rem;
+}
+
+.test-button:hover {
+  background-color: var(--success-hover);
+  border-color: transparent;
+}
+
+/* Adjust dashboard and login for new layout */
+.login-container {
+  display: flex;
+  justify-content: center;
+  align-items: center;
+  min-height: 100vh;
+  width: 100%;
+}