The color management system currently used by Web browser software is based on an 8-bit, 216-color (not 256) palette. The browser-safe color palette is a solution devised by Netscape to solve the problem of displaying color graphics in a similar way on many kinds of display screens, with browsers running under different operating systems (such as Macintosh, Windows, and UNIX). Because a majority of the Web audience years ago had 8-bit display screens, 256 colors was the upper limit for the color palette. But the various versions of the Windows operating system (which currently represent about 95 percent of the microcomputer market) reserve 40 colors for displaying such graphic interface elements as windows, menus, screen wallpaper, icons, and buttons, which leaves just 216 colors to display everything else. The 216 colors chosen by Netscape are identical in both the Macintosh and Windows system palettes. Although the browser-safe color scheme originated at Netscape, at present both of the dominant Web browsers (Netscape Navigator and Microsoft Internet Explorer) use the same color management system.

An RGB color value normally consists of a '#' immediately followed by a triad of two-digit hexadecimal numbers specifying the intensity of the corresponding color: (R)ed, (G)reen, and (B)lue. For example, the color value #FF0000 is rendered red because the red number is set to its highest value, FF (or 255, in decimal).

Each of the following style rules refer to the same color: namely, red. The three digit short-hand form is converted into the six-digit form by replicating digits (#F00 becomes #FF0000). The "functional" RGB notation uses a comma-separated list of decimal or percentage values.

EM { color: #f00; } /* #rgb */
EM { color: #ff0000; } /* #rrggbb */
EM { color: rgb(255, 0, 0); } /* integer range 0 - 255 */
EM { color: rgb(100%, 0%, 0%); } /* float range 0.0% - 100.0% */
EM { color: red; } /* color keyword */

VACCC (VisiBone Anglo-Centric Color Code) - There are 60 hues in the palette, and each one has a name here, for example Red, Red-Orange, Yellow-Spring, Magenta-Magenta-Violet. Some hues have as many as fifteen shades in the palette, some only one. The shades of a given hue are grouped together. The vividness of a shade is also called its saturation. The lightness/darkness is called its brightness or intensity.

This image is meant to be a picture of the 6x6x6 cube as seen from over the white and black corners. The line connecting the white and black corners are the axis of spin. The direction of spin is in a positive hue direction. If you take the palette in HSV (hue, saturation, value) coordinates and adjust only the hue, the result is the animation pictured here. You must have a browser that supports animated GIF images in order to see the animation.