title: Confounded by special CSS case
body: <p>I was watching <a href="http://www.youtube.com/watch?v=kXTP8XqrSwE" rel="nofollow">this</a> video, it's a short demo for the Brackets IDE. I'm new to web development so I anticipate being confused by the code I see but there was something in there that I really don't get. Around the 8 minute mark the guy brings up the css line <code>.galleryItem:nth-child(4n+1)</code> Saying that it will only affect the first item in each row in a grid because of the <code>:nth-child(4n+1)</code> can some one please explain the syntax of this line and how it can be used.</p>
  
  <p>P.S. For you Bret Victor fans out there, Brackets seems to do some of his stuff.</p>