<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>Document</title>
</head>
<body>
  <div class="container">
    <div class="row">
      <div class="col-4 order-3">
        <div class="box">1</div>
      </div>
      <div class="col-4 order-1">
        <div class="box">2</div>
      </div>
      <div class="col-4 order-2">
        <div class="box">3</div>
      </div>
    </div>
  </div>
</body>
</html>
.box{
  background: purple;
  height: 50px;
  border: solid 1px white;
  color: white;
}

External CSS

  1. https://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/4.1.3/css/bootstrap.min.css

External JavaScript

This Pen doesn't use any external JavaScript resources.