代码示例：（标识：bs_flex-align-items-start-responsive）
<!DOCTYPE html>
<html lang="en">
<head>
<title>Bootstrap 实例</title>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<link href="https://cdn.bootcdn.net/ajax/libs/twitter-bootstrap/5.1.2/css/bootstrap.min.css" rel="stylesheet">
<script src="https://cdn.bootcdn.net/ajax/libs/twitter-bootstrap/5.1.2/js/bootstrap.bundle.js"></script>
</head>
<body>
<div class="p-4">
<h2>从开头对齐项目</h2>
<p>使用 .align-items-*-start 类在不同屏幕上从开头对齐单行项目。</p>
<p>请调整浏览器窗口大小来查看效果。<b>Note:</b>align-items-stretch 是默认的。</p>
<p><code>.align-items-start</code>:</p>
<div class="d-flex align-items-start bg-light" style="height:150px">
<div class="p-2 border">Flex item 1</div>
<div class="p-2 border">Flex item 2</div>
<div class="p-2 border">Flex item 3</div>
</div>
<br>
<p><code>.align-items-sm-start</code>:</p>
<div class="d-flex align-items-sm-start bg-light" style="height:150px">
<div class="p-2 border">Flex item 1</div>
<div class="p-2 border">Flex item 2</div>
<div class="p-2 border">Flex item 3</div>
</div>
<br>
<p><code>.align-items-md-start</code>:</p>
<div class="d-flex align-items-md-start bg-light" style="height:150px">
<div class="p-2 border">Flex item 1</div>
<div class="p-2 border">Flex item 2</div>
<div class="p-2 border">Flex item 3</div>
</div>
<br>
<p><code>.align-items-lg-start</code>:</p>
<div class="d-flex align-items-lg-start bg-light" style="height:150px">
<div class="p-2 border">Flex item 1</div>
<div class="p-2 border">Flex item 2</div>
<div class="p-2 border">Flex item 3</div>
</div>
<br>
<p><code>.align-items-xl-start</code>:</p>
<div class="d-flex align-items-xl-start bg-light" style="height:150px">
<div class="p-2 border">Flex item 1</div>
<div class="p-2 border">Flex item 2</div>
<div class="p-2 border">Flex item 3</div>
</div>
<br>
<p><code>.align-items-xxl-start</code>:</p>
<div class="d-flex align-items-xxl-start bg-light" style="height:150px">
<div class="p-2 border">Flex item 1</div>
<div class="p-2 border">Flex item 2</div>
<div class="p-2 border">Flex item 3</div>
</div>
</div>
</body>
</html>
