title: CSS: Vertical and horizontally centered
body: <p>Challenge: you have an empty body tag. Its only child is a div. The div's height and width are unknown. Make the contents of the div vertically and horizontally centered, using CSS/HTML alone (no JavaScript).</p>
  
  <p>For a test sandbox, fork: <a href="http://jsfiddle.net/pB9hK/" rel="nofollow">http://jsfiddle.net/pB9hK/</a></p>