how to use col in bootstrap code example
Example 1: .col-12 bootstrap
.col-12{
flex: 0 0 100%;
max-width: 100%;
}
Example 2: a column inside another column bootstrap html
<div class="row">
<div class="col-sm-9">
Level 1: .col-sm-9
<div class="row">
<div class="col-8 col-sm-6">
Level 2: .col-8 .col-sm-6
</div>
<div class="col-4 col-sm-6">
Level 2: .col-4 .col-sm-6
</div>
</div>
</div>
</div>