<div class="container">
    

        <div class="row">
            <div class="col-xs-6 col-sm-6 col-md-6 col-lg-6" style="background: red">
                123<br/>123<br/>123<br/>123<br/>123<br/>123<br/>
            </div>
            <div class="col-xs-6 col-sm-6 col-md-6 col-lg-6" style="background: green">
                123<br/>
            </div>
        </div>
</div>

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.