added pseudo classes

Author: khan4019

css.html

@@ -333,7 +333,11 @@ <h2>13. media queries</h2>
   <p>ref: <a href="http://mobile.smashingmagazine.com/2010/07/19/how-to-use-css3-media-queries-to-create-a-mobile-version-of-your-website/">how to use media queries</a>, <a href="https://developer.mozilla.org/en-US/docs/Web/Guide/CSS/Media_queries">css media queries</a>, <a href="http://www.w3.org/TR/css3-mediaqueries/#media0">W3: media queries</a></p>
 </div>
 <div id="div_span">
-  <h2>13. something</h2>
+  <h2>13. pseudo class</h2>
+  <p><strong>Question:</strong> Whare are some peseudo classed u have used?</p>
+  <p><strong>Answer: </strong> pseudo class tells you specific state of an element. allow to style element dynamically. The most popular one is <code>:hover</code>. Besides i have used <code>:visited</code>, <code>:focus</code>, <code>:nth-child</code>, <code>nth-of-type</code>, <code>:link</code>, etc.</p>
+  <p>pseudo classes is better if you dont want to mess up with javascript however, pesudo-classes is slow to process and apply rules.</p>
+  <p>ref: <a href="http://coding.smashingmagazine.com/2011/03/30/how-to-use-css3-pseudo-classes/">How to use pseudo classes</a>, <a href="http://css-tricks.com/pseudo-class-selectors/">meet pseudo classes</a></p>
 </div>
 <div id="mtuli_lang">
   <h2>14. pre processor</h2>