guesstimate/client/src/routes/notfound/index.tsx

import React, { FunctionComponent } from "react";
import { Link } from 'react-router-dom';
import style from "./style.module.css";

const NotFound: FunctionComponent = () => {
    return (
        <div className={style.notFound}>
            <h1>Error 404</h1>
            <p>That page doesn't exist.</p>
            <Link to="/"><h4>Back to Home</h4></Link>
        </div>
    );
};

export default NotFound;