Web Design in a Nutshell, 3rd Edition

By RGB value

Within style sheets, RGB colors can be specified by any of the following methods:

    {color 
: #0000FF;}
    {color: #00F;}
    {color: rgb(0,0,255);}
    {color: rgb(0%, 0%, 100%);}

The first method uses three two-digit hexadecimal RGB values (for a complete explanation, see Appendix D). The second method uses a three-digit syntax, which is essentially converted to the six-digit form by replicating each digit (therefore, #00F is the same as #0000FF).

The last two methods use a functional notation specifying RGB values as a comma-separated list of regular values (from 0 to 255) or percentage values (from 0 to 100%). Note that percentage values can use decimals, e.g., rgb(0%, 50.5%, 33.3%).