JSFiddle - React, Tailwind, and code Playground

HTML

<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css">
<div class="row first-row">
  <div class="col-xs-6">
  Col-1
  </div>
  <div class="col-xs-6">
  Col-2
  </div>
</div>
<div class="row second-row">
  <div class="col-xs-6">
  Col-3
  </div>
  <div class="col-xs-6">
  Col-4
  </div>
</div>

CSS

.first-row {
  background: blue;
}
.second-row {
  background: red;
}