fix: add focus trap and accessibility tests for mobile menu (Closes #512)

src/features/landing/components/Navbar.test.tsx

@@ -1,5 +1,5 @@
 import { describe, it, expect, vi, beforeEach } from 'vitest'
-import { render, screen } from '@testing-library/react'
+import { render, screen, fireEvent } from '@testing-library/react'
 import userEvent from '@testing-library/user-event'
 import { MemoryRouter } from 'react-router-dom'
 import { I18nProvider } from '../../../shared/i18n'
@@ -81,3 +81,43 @@ describe('Navbar i18n strings', () => {
     expect(screen.getAllByText('Sign Out').length).toBeGreaterThanOrEqual(2)
   })
 })
+
+describe('Navbar mobile menu focus trap', () => {
+  beforeEach(() => {
+    vi.clearAllMocks()
+    document.body.innerHTML = ''
+  })
+
+  it('moves focus into the mobile menu when opened', async () => {
+    const user = userEvent.setup()
+    mockUseAuth.mockReturnValue({ isAuthenticated: false, logout: vi.fn() })
+    renderNavbar()
+
+    await user.click(screen.getByLabelText('Open menu'))
+
+    const mobileMenu = document.getElementById('mobile-menu')
+    expect(mobileMenu).toBeInTheDocument()
+    // The first focusable element inside the menu should receive focus.
+    expect(mobileMenu?.contains(document.activeElement)).toBe(true)
+  })
+
+  it('closes the mobile menu when Escape is pressed and returns focus to the toggle', async () => {
+    const user = userEvent.setup()
+    mockUseAuth.mockReturnValue({ isAuthenticated: false, logout: vi.fn() })
+    renderNavbar()
+
+    const toggle = screen.getByLabelText('Open menu')
+    await user.click(toggle)
+
+    // Mobile menu should be visible.
+    expect(screen.getByLabelText('Close menu')).toBeInTheDocument()
+
+    // Press Escape to close the menu.
+    fireEvent.keyDown(document.activeElement ?? document.body, { key: 'Escape' })
+
+    // Menu should close and the toggle button should regain focus.
+    expect(screen.getByLabelText('Open menu')).toBeInTheDocument()
+    // The toggle button should have focus (returnFocus from useFocusTrap).
+    expect(screen.getByLabelText('Open menu')).toHaveFocus()
+  })
+})

src/features/landing/components/Navbar.tsx

@@ -5,6 +5,7 @@ import { useState } from 'react'
 import { useModeAnimation } from 'react-theme-switch-animation'
 import { useTheme } from '../../../shared/contexts/ThemeContext'
 import { useAuth } from '../../../shared/contexts/AuthContext'
+import { useFocusTrap } from '../../../shared/utils/focusTrap'
 import grainlifyLogo from '../../../assets/grainlify_log.svg'
 
 export function Navbar() {
@@ -15,6 +16,12 @@ export function Navbar() {
     isDarkMode: theme === 'dark',
     onDarkModeChange: (isDark) => setThemeFromAnimation(isDark),
   })
+  const mobileMenuRef = useFocusTrap<HTMLDivElement>(mobileMenuOpen, {
+    onEscape: () => {
+      setMobileMenuOpen(false)
+      // Focus returns to the hamburger toggle automatically via useFocusTrap's returnFocus
+    },
+  })
 
   return (
     <nav
@@ -156,7 +163,7 @@ export function Navbar() {
 
         {/* Mobile Menu */}
         {mobileMenuOpen && (
-          <div id="mobile-menu" className="md:hidden mt-4 pb-4 space-y-4">
+          <div id="mobile-menu" ref={mobileMenuRef} className="md:hidden mt-4 pb-4 space-y-4">
             <a
               href="#features"
               className={`block transition-colors font-medium ${