如何在react js中根据具体的路由改变头部样式？

npm install react-router-dom

import { BrowserRouter as Router, Route, Switch, Link } from 'react-router-dom';

const Header = () => {
  return (
    <header>
      <nav>
        <ul>
          <li>
            <Link to="/">Home</Link>
          </li>
          <li>
            <Link to="/about">About</Link>
          </li>
          <li>
            <Link to="/contact">Contact</Link>
          </li>
        </ul>
      </nav>
    </header>
  );
};

const App = () => {
  return (
    <Router>
      <Header />
      <Switch>
        <Route exact path="/" component={Home} />
        <Route path="/about" component={About} />
        <Route path="/contact" component={Contact} />
      </Switch>
    </Router>
  );
};

const About = () => {
  return (
    <div>
      <h1>About Page</h1>
      <style>{`
        header {
          background-color: #f2f2f2;
        }
      `}</style>
    </div>
  );
};