title: How add "cover"/"shadow" on div?
body: <p>I want add "shadow"/"cover" (I'm not sure how to name it) to my div, with css.</p>
  
  <p>cover on:</p>
  
  <p><a href="http://imageshack.us/photo/my-images/842/shadowon.png/" rel="nofollow">http://imageshack.us/photo/my-images/842/shadowon.png/</a></p>
  
  <p>cover off:</p>
  
  <p><a href="http://imageshack.us/photo/my-images/502/shadowoff.png/" rel="nofollow">http://imageshack.us/photo/my-images/502/shadowoff.png/</a></p>
  
  <p>I can do it with an additional div using the <code>background-image</code> property where a png file with a small opacity is used. But I want solve this issue with css.</p>
  
  <p>It is possible?  </p>
  
  <p>Any help would be appreciated.</p>