使用Bootstrap中的.d-*-flex类，在特定的屏幕尺寸上创建一个flexbox容器。
对于不同的屏幕尺寸，将其用作“ d-sm-flex”，“ d-md-flex”等，如下所示-
<span class="d-sm-flex bg-warning"> Small Screen </span> <span class="d-md-flex bg-info"> Medium Screen </span> <span class="d-lg-flex bg-success"> Large Screen </span> <span class="d-xl-flex bg-danger"> Extra Large Screen </span>
在上方，弹性项目设置为小，中，大和超大屏幕尺寸。
让我们看一看该类及其实现的示例-
<!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/4.1.0/css/bootstrap.min.css"> <script src="https://cdn.staticfile.org/jquery/3.3.1/jquery.min.js"></script> <script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.1.0/js/bootstrap.min.js"></script> </head> <body> <div class="container mt-3"> <h2>Flex Example</h2> <div class="d-flex bg-primary">d-flex</div> <span class="d-sm-flex bg-warning">d-sm-flex</span> <span class="d-md-flex bg-info">d-md-flex</span> <span class="d-lg-flex bg-success">d-lg-flex</span> <span class="d-xl-flex bg-danger">d-xl-flex</span> </div> </body> </html>