JSFiddle - React, Tailwind, and code Playground

HTML

<script src="//code.jquery.com/jquery-3.3.1.slim.min.js"></script>
<link rel="stylesheet" href="//stackpath.bootstrapcdn.com/bootstrap/4.1.0/css/bootstrap.min.css">
<script src="//cdnjs.cloudflare.com/ajax/libs/popper.js/1.14.0/umd/popper.min.js"></script>
<script src="//stackpath.bootstrapcdn.com/bootstrap/4.1.0/js/bootstrap.min.js"></script>
<link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/font-awesome/4.7.0/css/font-awesome.min.css">
<!-- 
  Bootstrap docs: https://getbootstrap.com/docs
-->

<div class="container">
  <div class="row">
    <div class="col-md-4">
      <div class="postagem">1 de 3</div>
    </div>
    <div class="col-md-4">
      <div class="postagem">2 de 3</div>
    </div>
    <div class="col-md-4">
      <div class="postagem">3 de 3</div>
    </div>
  </div>
</div>

CSS

.container {
  margin: 20px;
}

.postagem {
  border: solid 1px #6c757d;
  padding: 10px;
}

.col-md-4:nth-child(1) > .postagem {
  background: #edc333;
}

.col-md-4:nth-child(2) > .postagem {
  background: #000;
}

.col-md-4:nth-child(3) > .postagem {
  background: #3e4095;
}