把 .well 用在元素上，就能有嵌入的简单效果。
well
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gbk"/>
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="Resource-type" content="Document"/>
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>组件-嵌入内容</title>
<link href="css/bootstrap.min.css" rel="stylesheet" type="text/css" />
<script src="js/jquery-2.1.4.min.js" type="text/javascript"></script>
<script src="js/bootstrap.min.js" type="text/javascript"></script>
<style>
<!--
.line{border-top:1px solid #afd9ee;margin:20px 0;}
-->
</style>
</head>
<body>
<div class="container">
<!--不需要为 <iframe> 元素设置 frameborder="0" 属性-->
<div class="row">
<div class="col-xs-6">
<div class="embed-responsive embed-responsive-16by9">
<iframe src="Assembly-Button.html" class="embed-responsive-item"></iframe>
</div>
</div>
<div class="col-xs-6">
<div class="embed-responsive embed-responsive-4by3">
<iframe src="Assembly-Nav.html" class="embed-responsive-item"></iframe>
</div>
</div>
</div>
<div class="line"></div>
<!--well-->
<div class="well">文本背景显示会有内嵌的效果</div>
<div class="well well-lg">well-lg</div>
<div class="well well-sm">well-sm</div>
</div>
</body>
</html>
