Outline Card Stack

The Outline is a new website from Joshua Topolsky and a great crew of assembled minds. It's got a unique design language: it's a bit marmite, but I particularly love the 'stacks' dotted through the interface like these:

I wanted to learn how to recreate the same stacked cards effect using purely CSS3 and HTML markup, including how the cards fan outwards when hovered over by the user. So I created this to show how I'm doing it.

Check out the Github Pages site for a demo.