center div middle of page bootstrap code example

Example 1: bootstrap 4 center div

<div class="d-flex justify-content-start">...</div>
<div class="d-flex justify-content-end">...</div>
<div class="d-flex justify-content-center">...</div>
<div class="d-flex justify-content-between">...</div>
<div class="d-flex justify-content-around">...</div>

Example 2: bootstrap div vertical center

<div class="jumbotron d-flex align-items-center min-vh-100">
  <div class="container text-center">
    I am centered vertically
  </div>
</div>