The CSS3 box-shadow property applies shadow to elements. Components of the box-shadow property are decoded by browsers in the following manner:
In the example below, the horizontal and vertical offsets have been set to 10px:
width: 300px;
height: 100px;
background-color: #9ACD32;
box-shadow: 10px 10px #888888;
Besides color, there are also two optional values for the box-shadow element, which are blur and spread.
box-shadow: 10px 10px 5px 5px #888888;
Negative values can also be used for the box-shadow property.
box-shadow: -10px -10px 5px -5px #888888;