<div class="container h-100">
<div class="d-flex flex-column justify-content-center h-100">
    <h1>Vertically centered text with Bootstrap 4 flexbox</h1>
    <p>Secondary text will also be vertically centered</p>
  <a href="http://bootstrapcreative.com/">Even me!</a>
  </div>
</div>  
body, html {height:100%;}

External CSS

  1. https://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/4.1.3/css/bootstrap.min.css

External JavaScript

  1. https://code.jquery.com/jquery-3.2.1.slim.min.js
  2. https://cdn.rawgit.com/JacobLett/bootstrap4-latest/504729ba/bootstrap-4-latest.min.js