Bootstrap 4 .card-header类
使用card-header类创建Bootstrap卡的标题-
<div class="card-header"> This is the header </div>
包括卡头之后，您可以添加卡主体和页脚，如以下代码片段所示：
<div class="card-body"> This is demo content. </div> <div class="card-footer"> This is the footer. </div>
您可以尝试运行以下代码以在Bootstrap4中实现card-header类-
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">
<h2>Demo Heading</h2>
<div class="card">
<div class="card-header">This is the header</div>
<div class="card-body">This is demo content.</div>
<div class="card-footer">This is the footer</div>
</div>
</div>
</body>
</html>