Answers for "bootstrapp grid"

col offset in bootstrap

.col-md-3 .offset-md-3

Bootstrap 4 Grid

<!-- Control the column width, and how they should appear on different devices -->
<div class="row">
  <div class="col-*-*"></div>
  <div class="col-*-*"></div>
</div>
<div class="row">
  <div class="col-*-*"></div>
  <div class="col-*-*"></div>
  <div class="col-*-*"></div>
</div>

<!-- Or let Bootstrap automatically handle the layout -->
<div class="row">
  <div class="col"></div>
  <div class="col"></div>
  <div class="col"></div>
</div>

.row bootstrap

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

.col-12 bootstrap

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

grid system bootstrap

Extra small  .col-    <576px	
Small  .col-sm- ≥576px	
Medium .col-md- ≥768px	
Large  .col-lg-  ≥992px	
Extra large .col-xl- ≥1200px