align items horizontally and vertically center bootstrap 4 code example

Example 1: bootstrap center align columns

<!-- Center columns in a Row -->
<div class="row d-flex justify-content-center text-center">
    <div class="col-4">
        // Add Content
    </div>
    <div class="col-4">
        // Add Content
    </div>
    <div class="col-4">
        // Add Content
    </div>
</div>

Example 2: html center image vertically bootstrap

mx-auto mt-auto mb-auto