JSFiddle - React, Tailwind, and code Playground

HTML

<!DOCTYPE html>
<html>
<head>
  <script src="http://code.jquery.com/jquery-latest.js"></script>
</head>
<body>
  <div class="widget">
      <h3 class="widget_title">My widget Title</h3>
    <p class="selected">Hello Again</p>
    <div><span>And Again</span></div>
  </div>
</body>
</html>

CSS

.inner_widget {
border:1px solid blue;
padding:10px;
}

.widget {
width:80%;
margin:0 auto;
border:1px solid red;
padding:10px;
}

.widget_title {
background:yellow;
}

JavaScript

$('.widget h3.widget_title').after('<div class="inner_widget">');