JSFiddle - React, Tailwind, and code Playground

HTML

<div class="panel panel-default">
 <div class="row">
 
 </div>
  <div class="panel-heading panel-heading-custom">
    <h3 class="panel-title">Panel title</h3>
  </div>
</div>

CSS

@import url('//maxcdn.bootstrapcdn.com/bootstrap/3.1.1/css/bootstrap.min.css');

.panel-default > .panel-heading-custom {
    background: #40ff00; color: #fff;
    text-align: center;
}