how to vertical align middle column content in bootstrap 4 code example
Example 1: 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>
Example 2: how to center vertically in bootstrap col
<div class="my-auto">
...inner divs and content...
</div>