The green box....

The red box

The yellow one!

                    Bluuuuuuue 

Hehehe!

Where it came from: 

http://www.quirksmode.org/css/opacity.html

http://web-wire.blogspot.com/2006/09/lesson-1-css-opacity.html

The assignment I was working on involved more absolute positioning, but someone had mentioned opacity
and I couldn't help wondering what would happen if those boxes overlapped each other  :-)