<div class="d-flex align-items-center">
<div class="p-2">Flex item 1</div>
<div class="p-2">Flex item 2</div>
<div class="p-2">Flex item 3</div>
</div>
<!-- responsive variations -->
<div class="d-flex align-items-sm-center">...</div>
<div class="d-flex align-items-md-center">...</div>
<div class="d-flex align-items-lg-center">...</div>
<div class="d-flex align-items-xl-center">...</div>