In HTML, colors are expressed either as hexadecimal values (for example, #FF0000) or as color names (red). The colors that are common to Netscape Navigator and Microsoft Internet Explorer on both Windows and Macintosh systems when running in 256-color mode are called Web-safe. The conventional wisdom is that there are 216 common colors, and that any hexadecimal value that combines the pairs 00, 33, 66, 99, CC, or FF (RGB values 0, 51, 102, 153, 204, and 255, respectively) represents a Web-safe color.
Testing, however, reveals that there are only 212 Web-safe colors. Internet Explorer on Windows does not correctly render the colors #0033FF (0,51,255), #3300FF (51,0,255), #00FF33 (0,255,51), and #33FF00 (51,255,0).
All of the color pickers in Dreamweaver use the 212-color Web-safe palette; selecting a color from the palette displays the color's hexadecimal value. While the four colors mentioned previously are not in the Dreamweaver Web-safe palette, you can edit the hexadecimal value in any color field by hand if you want to use them.
To choose a color outside the Web-safe range, click the Palette button in the lower right corner of the Dreamweaver color picker to open the system color picker. The system color picker is not limited to Web-safe colors.
UNIX versions of Netscape Navigator use a different color palette than the Windows and Macintosh versions. If you are developing exclusively for UNIX machines (or your target audience is Windows or Macintosh users with 24-bit monitors and UNIX users with 8-bit monitors), consider using hexadecimal values that combine the pairs 00, 40, 80, BF, or FF, which produce Web-safe colors on the SunOS.