This simple page has the Bootstrap css link tag in the head of the html and the bootstrap javascript library is included just before the end of the body tag.
<link href="https://cdn.jsdelivr.net/npm/bootstrap@5.3.0-alpha1/dist/css/bootstrap.min.css" rel="stylesheet" integrity="sha384-GLhlTQ8iRABdZLl6O3oVMWSktQOp6b7In1Zl3/Jr59b6EGGoI1aFkw7cmDA6j6gD" crossorigin="anonymous"/>
<script src="https://cdn.jsdelivr.net/npm/bootstrap@5.3.0-alpha1/dist/js/bootstrap.bundle.min.js" integrity="sha384-w76AqPfDkMBDXo30jS1Sgez6pr3x5MlQ1ZAGC+nuZB+EYdgRZgiwxhTBTkF7CXvN" crossorigin="anonymous"></script>
So... shrink the browser to see what happens to the elements such as navbar. Below are the bootstrap 5 breakpoint class specs laid out on this bootstrap doc page.
| Breakpoint | Class infix | Dimensions |
|---|---|---|
| X-Small | None | <576px |
| Small | sm |
≥576px |
| Medium | md |
≥768px |
| Large | lg |
≥992px |
| Extra large | xl |
≥1200px |
| Extra extra large | xxl |
≥1400px |