JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/2.2.4/jquery.js"></script>
<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/3.3.7/css/bootstrap.css">
<script src="https://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/3.3.7/js/bootstrap.js"></script>
<!-- NAVIGATION TOP -->
<nav class="navbar my-navbar navbar-inverse">
  <div class="container">
    <div class="navbar-header">

      <!-- LOGO -->
      <a href="#" class="navbar-brand"><img src="https://placehold.it/20x20" class="center-block"></a>
      <!-- LOGO -->
      <button type="button" class="navbar-toggle collapsed" data-toggle="collapse" data-target="#navbar">
        <span class="icon-bar"></span>
        <span class="icon-bar"></span>
        <span class="icon-bar"></span>
      </button>

    </div>
    <div id="navbar" class="collapse navbar-collapse">
      <ul class="nav navbar-nav navbar-right">
        <li><a href="#">Home</a></li>
        <li><a href="#">About</a></li>
        <li><a href="#">Services</a></li>
        <li><a href="#">Portfolio</a></li>
      </ul>
    </div>
    <!--/.nav-collapse -->
  </div>
</nav>

<!-- NAVIGATION TOP END -->
<!-- SHOWCASE -->
<section class="container">
  <div class="row">
    <div class="col-xs-offset-3 col-xs-6">
      <div class="maintext">Some text</div>
    </div>
  </div>
  <div class="maintext2">Some text</div>
  <div class="maintext3">Some text</div>

</section>
<!-- SHOWCASE END -->

CSS

@media(max-width: 768px) {
  .navbar-brand {
    display: block;
    float: none;
  }
  .navbar-header {
    position: relative;
  }
  .navbar-header > button {
    position: absolute;
    top: 8px;
    right: 15px;
    margin: 0;
  }
}

.maintext,
.maintext2,
.maintext3 {
  height: 100px;
  background-color: #eee;
  margin-bottom: 20px;
  padding: 5px;
}

.maintext2 {
  width: 200px;
  margin-left: auto;
  margin-right: auto;
}

.maintext3 {
  text-align: center;
}