Interesting CSS effect. Can anyone tell how its done?

Hi,
Just saw one CSS effect on one site (or at least I think its CSS although it look unbelievable to me) and I'm just curious to see how its done.

Open the link, look at the red logo circle at the left top and scroll down. How its done?

http://econsultancy.com/blog/3884-marketing-when-the-government-gets-it-oh-so-wrong

Thanks

 

The CSS part takes care of the image being visible while you scroll the page.
As for changing its color, that is java.
I know of no CSS trick to get that effect.

 

Yes, it's a CSS effect and there's an article on how to do it. Unforunately, I don't think I kept the link that describes it and I don't know when I'd have time to analyze it.

 

http://www.askthecssguy.com/2009/01/mike_asks_the_css_guy_about_a.html

 

Yep My220x. That's it.

 

Very simple but very effective.

 

Fantastic! Everyday I learn something new it seems.
Gotta love CSS !

 

Great CSS is mighty

 

LOL. I loved the paper shredder.

I've been designing with CSS for a good while and I still am getting "how in the heck" moments all the time.

I like the CssZen one (linked from that article) where the diver turns on his light as you get deeper into the page.