<!DOCTYPE html>
<html>
<head>
<title>Bootstrap Example</title>
<link rel = "stylesheet" href = "https://maxcdn.bootstrapcdn.com/bootstrap/4.1.1/css/bootstrap.min.css">
<script src = "https://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<script src = "https://maxcdn.bootstrapcdn.com/bootstrap/4.1.1/js/bootstrap.min.js"></script>
</head>
<body>
<div class = "container">
<div class = "alert alert-warning">
<p>Warning!</p>
</div>
</div>
</body>
</html>
原创文章，作者：ItWorker，如若转载，请注明出处：https://blog.ytso.com/264952.html