JSFiddle - React, Tailwind, and code Playground

HTML

<link rel="stylesheet" href="//maxcdn.bootstrapcdn.com/bootstrap/3.2.0/css/bootstrap.min.css">
<script src="//maxcdn.bootstrapcdn.com/bootstrap/3.2.0/js/bootstrap.min.js"></script>
<div class="progress">
  <div class="progress-bar progress-bar-success" style="width: 50%">
  </div>
  <span class="marcador"></span>
</div>

CSS

.marcador{
    display:inline-block;
    position:relative;
    top:0;
    left:10%;
    width:5px; 
    height:80px; 
    background-color:red;
}