CSS3 Box Shadow
Shadows have been around since the beginning of CSS2, however the only browser supporting them then (and continually now) was Safari. Shadows can be applied in CSS3 to borders, images as well as affecting text as well.
The CSS3 box-shadow is written box-shadow: Apx Bpx Cpx #XXX;
- Apx = x-axis
- Bpx = y-axis
- Cpx = cast length / feathering
- #XXX = colour as usual
This is a panel set with a 5 by 5 pixel box-shadow, cast by 7px.
- CSS3 Border Shadow
- #my_CSS3_id {
- border: 5px solid #c4c8cc;
- box-shadow: 5px 5px 7px #888;
- border-radius: 0 0 15px 0;
- }
This effect can also be applied to images... 
The Zen Elements CSS3 Series
- CSS3: Introduction
- CSS3: Border Image
- CSS3: Border Radius
- CSS3: Box Shadow
- CSS3: Font Face
- CSS3: Gradients
- CSS3: HSL & HSLA
- CSS3: Multiple Column
- CSS3: Multiple Images
- CSS3: Opacity
- CSS3: RGB & RGBA
- CSS3: Text Shadow
- CSS3: Transform
- CSS3: Transition
@zen