title: How the only class col-xs-12 works in large screen in bootstrap 3?
body: <p>Talking about grid system of bootstrap 3. If we use <code>col-xs-12</code> class in our code it will also works for big screen along with small screen, though not necessary to use <code>col-sm-12</code> or <code>col-md-12</code> or <code>col-lg-12</code> class.</p>
  
  <p>From the below image, it is clearly saying extra small size devices which is <code>col-xs-12</code> are used for <strong>&lt;768px</strong>. Then how can it works for large screen when we use <code>col-xs-12</code> only ?</p>
  
  <p><a href="https://i.stack.imgur.com/Ckguo.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/Ckguo.jpg" alt="enter image description here"></a></p>
  
  <p>From coding, this below codes will also work for large screen also though I used only <code>class="col-xs-12"</code>, did not use  <code>class="col-sm-12"</code> or  <code>class="col-md-12"</code> or  <code>class="col-lg-12"</code></p>
  
  <pre><code>&lt;div class="container"&gt;        
      &lt;div class="row"&gt;
          &lt;div class="col-xs-12"&gt;ABC&lt;/div&gt;            
      &lt;/div&gt;
  &lt;/div&gt;
  </code></pre>