Bootstrap 3 - 2 column nested rows

Question

I'm trying to achieve the following in Bootstrap 3 using as little of my own markup and CSS as possible. Ideally I'd like to achieve this using pure Bootstrap Markup without resorting to hacks. I've looked at the documentation but can't see a standardized way....

As you can see below, I'm trying to get two rows with a gap in the center.

My Markup as follows

<section class="row">

   <article class="col-sm-12 col-md-6">
     <!--ROW LEFT-->
     <div class="row">
      <div class="col-sm-4">col</div>
      <div class="col-sm-4">col</div>
      <div class="col-sm-4">col</div>
     </div>
   </article>

   <article class="col-sm-12 col-md-6">
     <!--ROW RIGHT-->
     <div class="row">
      <div class="col-sm-4">col</div>
      <div class="col-sm-4">col</div>
      <div class="col-sm-4">col</div>
     </div>
   </article>
</section>

The only similar example Bootstrap has in the Docs is below, but you don't get a gap in the center.

BOOTSTRAPS MARKUP

<div class="row">
  <div class="col-sm-12">
    <div class="row">
      <div class="col-sm-6">
      content
      </div>
      <div class="col-sm-6">
      content
      </div>
    </div>
  </div>
</div>

Answer 1

To expand on Skelly's answer, you can use Bootstrap's column offset classes to create gaps between columns:

<div class="container"><section class="row">

   <article class="col-sm-12 col-md-5">
     <!--ROW LEFT-->
     <div class="row" style="background-color:blue;">
      <div class="col-sm-4" style="background-color:orange;">col</div>
      <div class="col-sm-4" style="background-color:silver;">col</div>
      <div class="col-sm-4" style="background-color:orange;">col</div>
     </div>
   </article>

   <article class="col-sm-12 col-md-5 col-md-offset-2">
     <!--ROW RIGHT-->
     <div class="row" style="background-color:blue;">
      <div class="col-sm-4" style="background-color:silver;">col</div>
      <div class="col-sm-4" style="background-color:orange;">col</div>
      <div class="col-sm-4" style="background-color:silver;">col</div>
     </div>
   </article>

</section></div>

http://bootply.com/103191

This prevents having to add extra styles but does create a larger gap as you're using two virtual columns to create the space.

If you don't mind the extra space on the right, you could make the offset 1 instead.