Template

XS

Portrait Phones
<576px

SM

Landscape Phones
≥576px to <768px

MD

Tablets
≥768px to <992px

LG

Laptops
≥992px to <1200px

XL

Desktops
≥1200px

<!doctype html>
<html lang="en">
<head>
<!-- Required meta tags -->
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>Bootstrap v5</title>
<!-- Bootstrap CSS -->
<link href="https://cdn.jsdelivr.net/npm/bootstrap@5.0.1/dist/css/bootstrap.min.css" rel="stylesheet" integrity="sha384-EVSTQN3/azprG1Anm3QDgpJLIm9Nao0Yz1ztcQTwFspd3yD65VohhpuuCOmLASjC" crossorigin="anonymous">
<link rel="stylesheet" href="css/styles.css">
</head>
<body>
<nav class="navbar navbar-expand-lg navbar-dark bg-dark fixed-top">
<div class="container-fluid">
<a class="navbar-brand text-light" href="/index.html"><img src="img/home.png" alt="" class="bg-gradient rounded" style="height: 2rem; width: 2rem"></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" aria-current="page" href="index.html">Home</a>
</li>
<li class="nav-item dropdown">
<a class="nav-link dropdown-toggle" href="#" id="navbarDropdown" role="button" data-bs-toggle="dropdown" aria-expanded="false">
Grid
</a>
<ul class="dropdown-menu" aria-labelledby="navbarDropdown">
<li class="dropdown-item text-muted" aria-disabled="true">
Grid and Flexbox
</li>
<li><hr class="dropdown-divider"></li>
<li><a class="dropdown-item" href="container.html">
Containers
</a></li>
<li><a class="dropdown-item" href="grid.html">
Grid
</a></li>
</ul>
</li>
<li class="nav-item dropdown">
<a class="nav-link dropdown-toggle active" href="#" id="navbarDropdown" role="button" data-bs-toggle="dropdown" aria-expanded="false">
Utilities
</a>
<ul class="dropdown-menu" aria-labelledby="navbarDropdown">
<li class="dropdown-item text-muted" aria-disabled="true">Utilities</li>
<li><hr class="dropdown-divider"></li>
<li><a class="dropdown-item" href="typography.html">Typography</a></li>
<li><a class="dropdown-item" href="text.html">Text</a></li>
<li><a class="dropdown-item" href="#">Something else here</a></li>
</ul>
</li>
</ul>
<form class="d-flex">
<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>
<div id="main-container" class="container">
<!-- content here -->
</div>
</body>
<script src="https://cdn.jsdelivr.net/npm/bootstrap@5.0.2/dist/js/bootstrap.bundle.min.js" integrity="sha384-MrcW6ZMFYlzcLA8Nl+NtUVF0sA7MsXsP1UyJoMp4YLEuNSfAP+JcXn/tWtIaxVXM" crossorigin="anonymous"></script>
</html>

When using this method you should:
  1. install bootstrap using NPM
  2. copy bootstrap folder inside node_modules
  3. create a folder name it as vendor then paste the bootstrap folder there
  4. see sample output below
head section
<link ref="vendor/bootstrap/dist/css/bootstrap.min.css">
before the closing body tags
<script src="vendor/bootstrap/dist/js/bootstrap.min.js"></script>
Github will not recognized the file inside node_modules folder.

Head Section or Bootstrap section
<link href="https://cdn.jsdelivr.net/npm/bootstrap@5.0.2/dist/css/bootstrap.min.css" rel="stylesheet" integrity="sha384-EVSTQN3/azprG1Anm3QDgpJLIm9Nao0Yz1ztcQTwFspd3yD65VohhpuuCOmLASjC" crossorigin="anonymous">
<link href="https://cdn.jsdelivr.net/npm/bootstrap@5.0.1/dist/css/bootstrap.min.css" rel="stylesheet" integrity="sha384-+0n0xVW2eSR5OomGNYDnhzAbDsOXxcvSN1TPprVMTNDbiYZCxYbOOl7+AMvyTG2x" crossorigin="anonymous">
after closing body tags
<script> src="https://cdn.jsdelivr.net/npm/bootstrap@5.0.2/dist/js/bootstrap.bundle.min.js" integrity="sha384-MrcW6ZMFYlzcLA8Nl+NtUVF0sA7MsXsP1UyJoMp4YLEuNSfAP+JcXn/tWtIaxVXM" crossorigin="anonymous"></script>