Box Shadow

This feature permits implementation of multiple drop shadows (outer or inner) on box elements.  Shadows on the top of the list will cover those underneath.

Color The shadow’s color.
Opacity Controls the opacity level of the shadow.
Position Controls the shadow position for the current distance.
Inset If not checked, the shadow is assumed to be a drop shadow (underneath the box). When checked the shadow is drawn inside the box border, above the background, but below content.
Distance Specifies the size of outward expansion (or inward contraction for inner shadows) according to the specified angle.
Blur Controls the blur radius of the shadow.
Spread Controls the size of shadow. You can specify positive values to grow or negative values to shrink the shadow compared to the size of the parent element.

Using many shadows may slow down your website on older machines. Shadows DO NOT work in older browsers like IE 7/8 and some legacy mobile browsers. You can check a detailed compatibility list here.