```html
<!doctype html>
-<html lang="en">
+<html lang="en" data-bs-theme="dark">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>Bootstrap demo</title>
<link href="{{< param "cdn.css" >}}" rel="stylesheet" integrity="{{< param "cdn.css_hash" >}}" crossorigin="anonymous">
</head>
- <body data-bs-theme="dark">
+ <body>
<h1>Hello, world!</h1>
<script src="{{< param "cdn.js_bundle" >}}" integrity="{{< param "cdn.js_bundle_hash" >}}" crossorigin="anonymous"></script>
</body>