JSFiddle - React, Tailwind, and code Playground

HTML

<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-alpha.6/css/bootstrap.min.css">
      <div class="container">
        <div class="row justify-content-md-center">
          <div class="col-md-8">
              YYYYYY
          </div>
          <div class="col-md-4">
          XXXXXXXX
          </div>
        </div>
      </div>

CSS

.col-md-8 {
  background: red;
}

.col-md-4 {
  background: green;
}