title: Bootstrap grid 3 column layout doesn't work
body: <p>I think I looked everywhere and tried everything. 
  I want to make a footer for a website with 3 columns - in each one there's h4 header and image (png icon). Instead of getting 3 columns I got 1 column with everything stacked under each other.
  HTML code:</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;div class="footer"&gt;
        &lt;div class="container"&gt;
          &lt;div class="row"&gt;
            &lt;div class="col-sm-4"&gt;
              &lt;h4&gt;Instagram&lt;/h4&gt;
              &lt;a href="#" target="_blank"/&gt;&lt;img src="img/instagram.png"/&gt;&lt;/a&gt;
            &lt;/div&gt;
            &lt;div class="col-sm-4"&gt;
              &lt;h4&gt;Facebook&lt;/h4&gt;
              &lt;a href="#" target="_blank"/&gt;&lt;img src="img/facebook.png"/&gt;&lt;/a&gt;
            &lt;/div&gt;
            &lt;div class="col-sm-4"&gt;
              &lt;h4&gt;LinkedIn&lt;/h4&gt;
              &lt;a href="#" target="_blank"/&gt;&lt;img src="img/linkedin.png"/&gt;&lt;/a&gt;
            &lt;/div&gt;
          &lt;/div&gt;
        &lt;/div&gt;
      &lt;/div&gt;</code></pre>
  </div>
  </div>
  </p>
  
  <p>Any reason why? Thanks in advance.</p>