<div class="container">
  <h3>.no-guttersを設定した例</h3>
  <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>
  
  <h3>.no-gutters設定なし</h3>
  <div class="row">
     <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>
</div>
.row > [class*=col] {
    padding-top: .75rem;
    padding-bottom: .75rem;
    background-color: rgba(86,61,124,.15);
    border: 1px solid rgba(86,61,124,.2);
}
.row {
  background-color: rgba(86,61,124,.15);
}

h3 {
  margin-top: 1rem;
  text-align: center;
}

.container {
  margin-bottom: 20px;
}

External CSS

  1. https://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/4.0.0-beta.3/css/bootstrap.css

External JavaScript

This Pen doesn't use any external JavaScript resources.