<linkhref="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/css/bootstrap.min.css"rel="stylesheet"> code example
Example 1: bootstrap 4 cdn
<!-- Boostrap 4 CSS -->
<link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.4.1/css/bootstrap.min.css" integrity="sha384-Vkoo8x4CGsO3+Hhxv8T/Q5PaXtkKtu6ug5TOeNV6gBiFeWPGFN9MuhOf23Q9Ifjh" crossorigin="anonymous">
<script src="https://stackpath.bootstrapcdn.com/bootstrap/4.4.1/js/bootstrap.min.js" integrity="sha384-wfSDF2E50Y2D1uUdj0O3uMBJnjuUD4Ih7YwaYd1iqfktj0Uod8GCExl3Og8ifwB6" crossorigin="anonymous"></script>
<!-- Boostrap JS -->
<script src="https://code.jquery.com/jquery-3.4.1.slim.min.js" integrity="sha384-J6qa4849blE2+poT4WnyKhv5vZF5SrPo0iEjwBvKU7imGFAV0wwj1yYfoRSJoZ+n" crossorigin="anonymous"></script>
<script src="https://cdn.jsdelivr.net/npm/[email protected]/dist/umd/popper.min.js" integrity="sha384-Q6E9RHvbIyZFJoft+2mJbHaEWldlvI9IOYy5n3zV9zzTtmI3UksdQRVvoxMfooAo" crossorigin="anonymous"></script>
Example 2: bootstrap 4
<!-- CSS only -->
<link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.5.2/css/bootstrap.min.css" integrity="sha384-JcKb8q3iqJ61gNV9KGb8thSsNjpSL0n8PARn9HuZOnIxN0hoP+VmmDGMN5t9UJ0Z" crossorigin="anonymous">
<!-- JS, Popper.js, and jQuery -->
<script src="https://code.jquery.com/jquery-3.5.1.slim.min.js" integrity="sha384-DfXdz2htPH0lsSSs5nCTpuj/zy4C+OGpamoFVy38MVBnE+IbbVYUew+OrCXaRkfj" crossorigin="anonymous"></script>
<script src="https://cdn.jsdelivr.net/npm/[email protected]/dist/umd/popper.min.js" integrity="sha384-9/reFTGAW83EW2RDu2S0VKaIzap3H66lZH81PoYlFhbGU+6BZp6G7niu735Sk7lN" crossorigin="anonymous"></script>
<script src="https://stackpath.bootstrapcdn.com/bootstrap/4.5.2/js/bootstrap.min.js" integrity="sha384-B4gt1jrGC7Jh4AgTPSdUtOBvfO8shuf57BaghqFfPlYxofvL8/KUEfYiJOMMV+rV" crossorigin="anonymous"></script>
Example 3:
<link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.4.1/css/bootstrap.min.css" integrity="sha384-Vkoo8x4CGsO3+Hhxv8T/Q5PaXtkKtu6ug5TOeNV6gBiFeWPGFN9MuhOf23Q9Ifjh" crossorigin="anonymous">
Example 4: bootstrap
<svg width="1em" height="1em" viewBox="0 0 16 16" class="bi bi-house-door-fill" fill="currentColor" xmlns="http://www.w3.org/2000/svg">
<path d="M6.5 10.995V14.5a.5.5 0 0 1-.5.5H2a.5.5 0 0 1-.5-.5v-7a.5.5 0 0 1 .146-.354l6-6a.5.5 0 0 1 .708 0l6 6a.5.5 0 0 1 .146.354v7a.5.5 0 0 1-.5.5h-4a.5.5 0 0 1-.5-.5V11c0-.25-.25-.5-.5-.5H7c-.25 0-.5.25-.5.495z"/>
<path fill-rule="evenodd" d="M13 2.5V6l-2-2V2.5a.5.5 0 0 1 .5-.5h1a.5.5 0 0 1 .5.5z"/>
</svg>
Example 5: Bootstrap
<!DOCTYPE html>
<html lang="en">
<head>
<title>Bootstrap Example</title>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.4.1/css/bootstrap.min.css">
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.5.1/jquery.min.js"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.4.1/js/bootstrap.min.js"></script>
</head>
<body>
<div class="jumbotron text-center">
<h1>My First Bootstrap Page</h1>
<p>Resize this responsive page to see the effect!</p>
</div>
<div class="container">
<div class="row">
<div class="col-sm-4">
<h3>Column 1</h3>
<p>Lorem ipsum dolor sit amet, consectetur adipisicing elit...</p>
<p>Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris...</p>
</div>
<div class="col-sm-4">
<h3>Column 2</h3>
<p>Lorem ipsum dolor sit amet, consectetur adipisicing elit...</p>
<p>Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris...</p>
</div>
<div class="col-sm-4">
<h3>Column 3</h3>
<p>Lorem ipsum dolor sit amet, consectetur adipisicing elit...</p>
<p>Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris...</p>
</div>
</div>
</div>
</body>
</html>