Bootstrap 4

HTML

<script src="bootstrap"></script>
<script src="bootstrap.min.cs"></script>
<link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.1.3/css/bootstrap.min.css" integrity="sha384-MCw98/SFnGE8fJT3GXwEOngsV7Zt27NXFoaoApmYm81iuXoPkFOJwJ8ERdknLPMO" crossorigin="anonymous">

<div class=" h-100 d-flex justify-content-center align-items-center">
  <div>
    Items are Centered horizontally and vertically
  </div>
</div>

CSS

html,
body {
  height: 100%;
}