Answers for "how to center grid bootstrap"

bootstrap 4 center div

<div class="d-flex justify-content-start">...</div>
<div class="d-flex justify-content-end">...</div>
<div class="d-flex justify-content-center">...</div>
<div class="d-flex justify-content-between">...</div>
<div class="d-flex justify-content-around">...</div>

.col-12 bootstrap

.col-12{
	flex: 0 0 100%;
	max-width: 100%;
}