If you want to maintain the collapsed state of the navbar on all screen sizes, simply update the
class=" navbar navbar-expand-lg bg-body-tertiary"
line to
class="navbar bg-body-tertiary"
This adjustment will ensure that the navbar remains collapsed across different screen sizes.
<!doctype html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<link href="https://cdn.jsdelivr.net/npm/<a href="/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="462429293235323427360673687568766b272a362e2775">[email protected]</a>/dist/css/bootstrap.min.css" rel="stylesheet">
<link href="https://getbootstrap.com/docs/5.3/assets/css/docs.css" rel="stylesheet">
<title>Bootstrap Example</title>
<script src="https://cdn.jsdelivr.net/npm/<a href="/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="d6b4b9b9a2a5a2a4b7a696e3f8e5f8e6fbb7baa6beb7e5">[email protected]</a>/dist/js/bootstrap.bundle.min.js"></script>
</head>
<body class="p-3 m-0 border-0 bd-example">
<!-- Example Code -->
<nav class="navbar bg-body-tertiary">
<div class="container-fluid">
<a class="navbar-brand" href="#">Navbar</a>
<button class="navbar-toggler" type="button" data-bs-toggle="collapse" data-bs-target="#navbarSupportedContent" aria-controls="navbarSupportedContent" aria-expanded="false" aria-label="Toggle navigation">
<span class="navbar-toggler-icon"></span>
</button>
<div class="collapse navbar-collapse" id="navbarSupportedContent">
<ul class="navbar-nav me-auto mb-2 mb-lg-0">
<li class="nav-item">
<a class="nav-link active" aria-current="page" href="#">Home</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#">Link</a>
</li>
<li class="nav-item dropdown">
<a class="nav-link dropdown-toggle" href="#" role="button" data-bs-toggle="dropdown" aria-expanded="false">
Dropdown
</a>
<ul class="dropdown-menu">
<li><a class="dropdown-item" href="#">Action</a></li>
<li><a class="dropdown-item" href="#">Another action</a></li>
<li><hr class="dropdown-divider"></li>
<li><a class="dropdown-item" href="#">Something else here</a></li>
</ul>
</li>
<li class="nav-item">
<a class="nav-link disabled">Disabled</a>
</li>
</ul>
<form class="d-flex" role="search">
<input class="form-control me-2" type="search" placeholder="Search" aria-label="Search">
<button class="btn btn-outline-success" type="submit">Search</button>
</form>
</div>
</div>
</nav>
<!-- End Example Code -->
</body>
</html>