Tutorial 3D Inset Effect by CSS3

People love to make flat things appear as if they're
three-dimensional. There are two ways to pull off this effect in a 2D
environment, shape and movement.
By give a flat shape the appearance of edges or sides, we can make
buttons or other objects appear as if they are raised or sunken into the
screen.

The movement effect is a bit trickier. In a three-dimensional world,
objects closer to