源代码：
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<!DOCTYPE html> <html> <head> <title>Bootstrap 实例</title> <meta charset="utf-8"> <meta name="viewport" content="width=device-width, initial-scale=1"> <link rel="stylesheet" href="https://cdn.staticfile.org/twitter-bootstrap/4.3.1/css/bootstrap.min.css"> <script src="https://cdn.staticfile.org/jquery/3.2.1/jquery.min.js"></script> <script src="https://cdn.staticfile.org/popper.js/1.15.0/umd/popper.min.js"></script> <script src="https://cdn.staticfile.org/twitter-bootstrap/4.3.1/js/bootstrap.min.js"></script> </head> <body> <div class="container mt-3"> <h2>子元素对齐</h2> <p>如果要设置单行的子元素对齐可以使用 .align-content-* 类来控制。</p> <p>.align-items-start:</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>.align-items-end:</p> <div class="d-flex align-items-end 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>.align-items-center:</p> <div class="d-flex align-items-center 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>.align-items-baseline:</p> <div class="d-flex align-items-baseline 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>.align-items-stretch (默认):</p> <div class="d-flex align-items-stretch 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> </div> </body> </html>
运行结果