bootstrap 4 col sm 8 center code example
Example: bootstrap col-md-5 center
<div class="container">
<div class="row">
<div class="col-sm-5 mx-auto">
Centered
</div>
</div>
</div>
<div class="container">
<div class="row">
<div class="col-sm-5 mx-auto">
Centered
</div>
</div>
</div>