function App() {
  return (
    <div>
      <Switch>
        <Route exact path="/" component={HomePage} />
        <Route component={NotFoundPage} />
      </Switch>
      <GlobalStyle />
    </div>
  );
}
App.js

This component is the skeleton around the actual pages, and should only
contain code that should be seen on all pages. (e.g. navigation bar)