Answers for "bootstrap 4 grid mixins"

no-gutter bootstrap 4

<div class="row no-gutters">
  <div class="col-12 col-sm-6 col-md-8">.col-12 .col-sm-6 .col-md-8</div>
  <div class="col-6 col-md-4">.col-6 .col-md-4</div>
</div>

.row bootstrap

.row{
    display: flex;
    flex-wrap: wrap;
	margin-right: -15px;
    margin-left: -15px;
}