JSFiddle - React, Tailwind, and code Playground

HTML

<link rel="stylesheet" href="//maxcdn.bootstrapcdn.com/bootstrap/3.2.0/css/bootstrap.min.css">
<div class="container">
    <div class="row">
      <main class="col-lg-9 col-md-9 col-sm-9 col-xs-12">
        <div class="col-lg-6 col-md-6 col-sm-6">
          <div class="background">Lore ipsum col-6.</div>
        </div>
        <div class="col-lg-6 col-md-6 col-sm-6 col-xs-12">
          <div class="background">Lore ipsum col-6.</div>
        </div>
      </main>
      <aside class="col-lg-3 col-md-3 col-sm-3 col-xs-12">
        <div class="background">Lore ipsum col-3</div>
      </aside>
    </div>
  </div>

CSS

.background {background-color: #ddd;}