src/pages/404.jsx
import * as React from 'react';
import { Seo } from '../shared/components/Seo';
const NotFoundPage = () => (
<>
<h1>404: Not Found</h1>
<p>You just hit a route that doesn't exist... the sadness.</p>
</>
);
export const Head = () => <Seo title='Page not found' />;
export default NotFoundPage;