<div id="root" style="min-width:300px;" />

/* Always do this.. */
.col-sm {
  border: 0 solid red;
}

/* Before the columns stack, do this */
@media (min-width: 576px) {
  .col-sm:last-child {
    border-width: 0 0 0 1px;
  } 
  .col-sm:first-child {
    border-width: 0 1px 0 0;
  }
}

/* when the columns stack, do something else */
@media (max-width: 575px)  {
  .col-sm {
    padding-bottom: 10px;
    margin-bottom: 10px;
  }
  .col-sm:last-child {
    border-color: lightgrey;
    border-width: 0 0 0 0;
  }
  .col-sm {
    border-color: lightgrey;
    border-width: 0 0 1px 0;
  }
}
 
// The main App class to render out our components and layout
class App extends React.Component {
  render() {
    return (
      <div>
        <PageOverview />
        <GridComponent />
      </div>
    )
  }
}

// Component to display a grid on the page
const GridComponent = () => {
  return(
    <div>
      <div class="container">
        <div class="row">
          <div class="col-sm text-info">
            {infoText}
          </div>
          <div class="col-sm">
            {hipsumText}
          </div>
          <div class="col-sm">
            {hipsumText}
          </div>
        </div>
      </div>
    </div>
    )
}

const infoText = "This example shows how you might alter the layout of a three column grid using the standard Bootstrap breakpoint of 576 pixels. Before the grid is stacked, we put vertical red lines between the columns and after the grid is stacked (below 576 pixels) the blocks of text have a grey border between them."

const hipsumText = "Lorem ipsum dolor amet hell of non nisi, DIY truffaut 3 wolf moon chillwave. Sint mixtape tilde poutine art party tumblr. Bespoke kinfolk kitsch activated charcoal. Semiotics meggings ipsum, photo booth labore taiyaki iPhone food truck. Drinking vinegar shabby chic schlitz, cloud bread vegan proident occaecat live-edge. Gochujang live-edge retro literally leggings flexitarian. Cronut post-ironic irony, artisan +1 raw denim paleo pickled ut hella wolf gluten-free culpa."

// Component for information at the top of the page
const PageOverview = () => {
  return(
  <div className="alert alert-secondary text-center">
      <div class="card text-center">
        <div class="card-body">
          <h4 class="card-title">React &amp; Bootstrap Responsive Grid Starter</h4>
          <p class="card-text">A React &amp; Twitter Bootstrap Responsive Grid Implementation</p>
    <div class="alert alert-info mb-0">
          <a href="https://getbootstrap.com/docs/4.1/layout/grid/" target="_blank">
          Twitter Bootstrap Documentation Click Here
        </a>
       </div>
        </div>
        <div class="card-footer text-muted" style={{fontSize:".9em"}}>
          Codepen created by Matt Howey :: <a href="https://www.howeydesign.com/" target="_blank"> @howeydesign</a>
        </div>
      </div>
    </div>
    )
}
// Render the App to the root node
ReactDOM.render(<App />, document.querySelector("#root"))
View Compiled

External CSS

  1. https://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/4.1.3/css/bootstrap.min.css

External JavaScript

  1. https://cdnjs.cloudflare.com/ajax/libs/react/16.6.3/umd/react.production.min.js
  2. https://cdnjs.cloudflare.com/ajax/libs/react-dom/16.6.3/umd/react-dom.production.min.js