I put together an example.
I am using jQuery to initialize the animation.
Though I think this could be done in pure CSS.
The main thing you can learn from my example is…
When you set a property to “transition” with CSS, changes to that property will be animated.
In the example, any changes made to “left:” will be animated.
I wrote the stylesheet in SCSS using compass. To see the pure CSS click on “CSS (SCSS)” at the top of the center box.