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