<html>
<head>
<meta charset="UTF-8">
<title>Untitled Page</title>
<meta name="viewport" content="width=device-width, initial-scale=1">
<style>
body {
    max-width: 100ch;
    margin: 0 auto;
    padding: 2em;
    line-height: 1.4em;
}
:target {
    background: palegoldenrod;
}
header::after {
    content: "";
    display: block;
    border-top: 1px solid gray;
}
</style>
</head>
<body>
<header>
<h1>Untitled Page</h1>
</header>
<main>
<article>This content is replaced.</article>
</main>
</body>
</html>