如何使侧边栏或顶部栏不会消失，当我导航到另一个页面？

.sidebar {
    position: fixed;
    top: 0;
    left: 0;
    width: 200px;
    height: 100%;
    background-color: #f4f4f4;
}

.header {
    position: fixed;
    top: 0;
    width: 100%;
    background-color: #333;
    color: white;
    padding: 10px 0;
}

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

function App() {
    return (
        <Router>
            <div>
                <Header />
                <Sidebar />
                <Route path="/" exact component={Home} />
                <Route path="/about" component={About} />
            </div>
        </Router>
    );
}

function Header() {
    return <header>My Website Header</header>;
}

function Sidebar() {
    return (
        <aside>
            <nav>
                <Link to="/">Home</Link>
                <Link to="/about">About</Link>
            </nav>
        </aside>
    );
}

<div id="header">My Website Header</div>
<div id="sidebar">
    <a href="#" onclick="loadPage('home')">Home</a>
    <a href="#" onclick="loadPage('about')">About</a>
</div>
<div id="content"></div>

<script>
function loadPage(page) {
    fetch(`/pages/${page}.html`)
        .then(response => response.text())
        .then(data => {
            document.getElementById('content').innerHTML = data;
        });
}
</script>