How to animate a 404 page with CSS3

Ten years ago when i was asked to make an animation, i would usually open up Flash and start with the animation. To be honest, i never liked the user interface but spent quite some time in that application. After the animation was finished, the normal export for the web would be the thing to do before embedding the auto generated code into your HTML document. And that was it. But since flash animation is slowly disappearing from websites - because of the lack of support on tablets on smartphones - i'm coding animation in CSS3. It's not as intuitive as with Flash but it will get you somewhere ... Here's a little tutorial on how i did a 404 Page not found animation