can some css help to achieve this effect. "Splitting 2 images"

Hello Friends!
I'd kindly ask you for some help. I'm trying to recreate the effect in this page:

http://bitly.com/19FivSo

This is, making 2 images opening as a curtain after clicking an image.
can some css help to achieve this effect. "Splitting 2 images"

Any help will be greatly appreciated :smiley:

Have a nice day!