Perspective Effect Achieved With Colors

Blue can create the illusion of perspective: The cooler and paler a color, the farther from you it seems; the warmer and deeper a color, the nearer to you it seems:

 
Perspective effect

What we see here are red spots. We would never think that this light-blue area has holes and is in front of a red background.
The reason for this phenomenon is very easy to explain: In nature, all objects seem to be the farther away, the paler they are in color and they seem to be the nearer, the deeper their color is. Our visual system has adapted to the circumstances of nature in the course of evolution. Pale and bluish objects seem to be far away; deep and colorful objects seem to be nearer:

Perspective effect: Graphics of a landscape

We could achieve the illusion of perspective on the web site with the help of colors: On a pale, pastel-colored background, a deep-colored 3-D-button with shadow effect conveys even more perspective. Inversely, a pale 3-D-button on a deep-colored background would strike us as being odd.