A CodePen by Jeroen Franse. Toggle switch with checkbox:checked - Round switch button in css with animation cleaned up.
Inspired on the design of Paul Flavius, see:

http://psd.tutsplus.com/tutorials/interface-tutorials/round-switch-button/

It is pure CSS, and animated so don't forget to click this very special checkbox. And in case you wonder: yes, this checkbox can be used in forms just as if it was a normal checkbox!

PS: can anyone confirm the animation with :checked state in safari?