otstrap grid system.</p>

      <h3>Five grid tiers</h3>
      <p>There are five tiers to the Bootstrap grid system, one for each range of devices we support. Each tier starts at a minimum viewport size and automatically applies to the larger devices unless overridden.</p>

      <div class="row">
        <div class="col-4">.col-4</div>
        <div class="col-4">.col-4</div>
        <div class="col-4">.col-4</div>
      </div>

      <div class="row">
        <div class="col-sm-4">.col-sm-4</div>
        <