Shadow behind element

[jimfog]

I have noticed in many sites that behind some element the effect of a shadow is achieved-usually the shadow i notice is either of the black or the white color.How is this shadow achieved?Here is an example so you can understand what i am talking about: www.joomla.org As you can see there in the top section(especially) of the main div element there is a white shadow. This, progressively, is replaced by a black one-it is rather faint i would say, you need to be cautious to observe it.In general, the main div gives the impression to the eye that "Sit on top of a cloud".Can someone explain me please how this is achieved?I could give other examples also-i have noticed the above in numerous occasions. Thanks

[Synook]

The easiest way to get a shadow is just to use an image. You can set it as the background and repeat it.

[jimfog]

The easiest way to get a shadow is just to use an image. You can set it as the background and repeat it.

Oh, that is what i thought myself.Thanks.