title: It is necessary to fill all 12 columns of a row of bootstrap's grid system?
body: <p>It is necessary to fill all 12 columns of a row?</p>
  
  <p>Example 1 - only 2 columns from a total 12 of the row are declared:</p>
  
  <pre><code>&lt;div class="container"&gt;
    &lt;div class="row"&gt;
      &lt;div class="col-sm-2"&gt;
        ...
      &lt;/div&gt;
    &lt;/div&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>Example 2 - the unused columns are declared too:</p>
  
  <pre><code>&lt;div class="container"&gt;
    &lt;div class="row"&gt;
      &lt;div class="col-sm-2"&gt;
        ...
      &lt;/div&gt;
      &lt;div class="col-sm-10"&gt;&lt;/div&gt;
    &lt;/div&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p><strong>It is possible for a browser to scale the 2 example in different ways?</strong>
  I tend to think that a good practice is the Example 2.</p>