Bootstrap CSS class .col-*

<!-- responsive equal width cols, can be sm, md, lg, or xl -->
<div class="container">
  <div class="row">
    <div class="col-sm">1 of 3</div>
    <div class="col-sm">1 of 3</div>
    <div class="col-sm">1 of 3</div>
  </div>
</div>