RGB(Red-Green-Blue)

The RGB color model is used in numerical color specifications.

The format of the RGB Value

#rgb
The format of an RGB value in hexadecimal notation is a ‘#’ immediately followed by three hexadecimal characters(0-9, A-F).

#rrggbb
The format of an RGB value in hexadecimal notation is a ‘#’ immediately followed by six hexadecimal characters(0-9, A-F).

rgb(R,G,B) -integer-
The format of an RGB value in the functional notation is ‘rgb(’ followed by a comma-separated list of three numerical values (three integer values(0-255, 0-255, 0-255)) followed by ‘)’.

rgb(R,G,B) -percentage-
The format of an RGB value in the functional notation is ‘rgb(’ followed by a comma-separated list of three numerical values (three percentage values(0%-100%, 0%-100%, 0%-100%)) followed by ‘)’.

Example

Some examples are as follow:

#rgb	#rrggbb	rgb(integer)	rgb(percentage)
#000	#000000	rgb(0,0,0)	rgb(0%,0%,0%)
#FFF	#FFFFFF	rgb(255,255,255)	rgb(100%,100%,100%)
#F00	#FF0000	rgb(255,0,0)	rgb(100%,0%,0%)
#0F0	#00FF00	rgb(0,255,0)	rgb(0%,100%,0%)
#00F	#0000FF	rgb(0,0,255)	rgb(0%,0%,100%)

Point, Note

Values outside the device gamut should be clipped or mapped into the gamut when the gamut is known: the red, green, and blue values must be changed to fall within the range supported by the device.

em { color: rgb(255,0,0) }       /* integer range 0 - 255 */
em { color: rgb(300,0,0) }       /* clipped to rgb(255,0,0) */
em { color: rgb(255,-10,0) }     /* clipped to rgb(255,0,0) */
em { color: rgb(110%, 0%, 0%) }  /* clipped to rgb(100%,0%,0%) */

CSS Reference

CSS Color defines the RGB color values in 4.2.1. RGB color values.