Can anyone tell me how on the apple website link they made it so when you click either 17 inch, 20 inch, or 24 inch, the new image fades in?:

http://store.apple.com/1-800-MY-APPL...34A4&nclm=iMac

I looked at the code and saw where the 17 inch computer image is but I don't understand where they refer to the 20 and 24 inch and make it fade in.

Thanks for your help. I really appreciate it.