<!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/4.5.2/css/bootstrap.min.css">
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.5.1/jquery.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.16.0/umd/popper.min.js"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.5.2/js/bootstrap.min.js"></script>
</head>
<body>
<div class="container mt-3">
<h2>Vertical Direction</h2>
<p>Use .flex-column to display the flex items vertically (on top of each other).</p>
<p>Use .flex-sm|md|lg|xl-column to achieve this on different screen sizes.</p>
<p><code>.flex-column</code>:</p>
<div class="d-flex flex-column mb-3">
<div class="p-2 bg-info">Flex item 1</div>
<div class="p-2 bg-warning">Flex item 2</div>
<div class="p-2 bg-primary">Flex item 3</div>
</div>
<p><code>.flex-sm-column</code>:</p>
<div class="d-flex flex-sm-column mb-3">
<div class="p-2 bg-info">Flex item 1</div>
<div class="p-2 bg-warning">Flex item 2</div>
<div class="p-2 bg-primary">Flex item 3</div>
</div>
<p><code>.flex-md-column</code>:</p>
<div class="d-flex flex-md-column mb-3">
<div class="p-2 bg-info">Flex item 1</div>
<div class="p-2 bg-warning">Flex item 2</div>
<div class="p-2 bg-primary">Flex item 3</div>
</div>
<p><code>.flex-lg-column</code>:</p>
<div class="d-flex flex-lg-column mb-3">
<div class="p-2 bg-info">Flex item 1</div>