src/components/Layout/Header.js

import React from 'react';
import styled from 'styled-components';
import { Link } from 'react-router-dom';
import ThemeToggle from '../UI/ThemeToggle';
import { useAuth } from '../../hooks/useAuth';

const HeaderContainer = styled.header`
  background: ${({ theme }) => theme.colors.primary};
  color: white;
  padding: 1rem 2rem;
  box-shadow: ${({ theme }) => theme.shadows.medium};
`;

const Nav = styled.nav`
  display: flex;
  justify-content: space-between;
  align-items: center;
  max-width: 1200px;
  margin: 0 auto;
`;

const Logo = styled(Link)`
  font-size: ${({ theme }) => theme.fontSizes.xxlarge};
  font-weight: bold;
  color: white;
  text-decoration: none;
  font-family: ${({ theme }) => theme.fonts.secondary};
`;

const NavLinks = styled.div`
  display: flex;
  gap: 2rem;
  align-items: center;
`;

const NavLink = styled(Link)`
  color: white;
  text-decoration: none;
  font-weight: 500;
  transition: opacity 0.3s ease;
  
  &:hover {
    opacity: 0.8;
  }
`;

const Header = () => {
  const { isAuthenticated } = useAuth();
  
  return (
    <HeaderContainer>
      <Nav>
        <Logo to="/">EnlightenQalb</Logo>
        <NavLinks>
          <NavLink to="/">Home</NavLink>
          {isAuthenticated && <NavLink to="/dashboard">Dashboard</NavLink>}
          <NavLink to="/about">About</NavLink>
          <ThemeToggle />
          {isAuthenticated ? <LogoutButton /> : <LoginButton />}
        </NavLinks>
      </Nav>
    </HeaderContainer>
  );
};

const LoginButton = () => (
  <NavLink to="/login">Login</NavLink>
);

const LogoutButton = () => {
  const { logout } = useAuth();
  
  return (
    <NavLink as="button" onClick={logout} style={{ background: 'none', border: 'none' }}>
      Logout
    </NavLink>
  );
};

export default Header;