2.2.9 [CSS-Level2-2009] Section 4.3.6, Colors


The specification states:

 The format of an RGB value in the functional notation is 'rgb(' followed by a 
 comma-separated list of three numerical values (either three integer values or 
 three percentage values) followed by ')'. The integer value 255 corresponds to 
 100%, and to F or FF in the hexadecimal notation: rgb(255,255,255) = 
 rgb(100%,100%,100%) = #FFF. White space characters are allowed around the numerical 

Quirks Mode and IE7 Mode (All Versions)

The RGB value allows both percentages and numbers in the notation.