<link href="//maxcdn.bootstrapcdn.com/bootstrap/3.3.0/css/bootstrap.min.css" rel="stylesheet" id="bootstrap-css">
<script src="//maxcdn.bootstrapcdn.com/bootstrap/3.3.0/js/bootstrap.min.js"></script>
<script src="//cdnjs.cloudflare.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script>
<div class="container">
<div class="row">
<div class="col-md-12 text-center ">
<button class="btn btn-default btn_text">
<span data-text="E">e</span>
<span data-text="X">x</span>
<span data-text="P">p</span>
<span data-text="L">l</span>
<span data-text="O">o</span>
<span data-text="R">r</span>
<span data-text="E">e</span>
</button>
</div>
</div>
</div>
