<div class="d-flex flex-wrap align-content-start">
<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-start">...</div>
<div class="d-flex align-content-md-start">...</div>
<div class="d-flex align-content-lg-start">...</div>
<div class="d-flex align-content-xl-start">...</div>
You don't need to remember all CSS classes. Just use the Bootstrap Editor instead.