在Bootstrap 4中，如果您希望flex项目占用可用空间，请使用flex-grow- | 1类。
如果您希望第一个弹性项目占用空间，那么以下是代码-
<div class="d-flex mb-3"> <div class="p-2 flex-grow-1 bg-warning">One</div> <div class="p-2 bg-secondary">Two</div> <div class="p-2 bg-danger">Three</div> </div>
在上面可以看到，我在第一个div类中使用了flex-grow-1类-
<div class="p-2 flex-grow-1 bg-warning"> One </div>
以下是实现flex-grow-0 | 1类的示例-
<!DOCTYPE html> <html> <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" <div class="d-flex mb-3"> <div class="p-2 flex-grow-1 bg-warning">One</div> <div class="p-2 bg-secondary">Two</div> <div class="p-2 bg-danger">Three</div> </div> </div> </body> </html>