Colors may be specified by using a standard name (such as aqua
) or a hexadecimal RGB value (such as #00FFFF
for aqua
). Of the six hexadecimal digits in an RGB value, the first two represent the amount of red in the color, the middle two represent the amount of green in the color and the last two represent the amount of blue in the color. For example, black
is the absence of color and is defined by #000000
, whereas white
is the maximum amount of red, green and blue and is defined by #FFFFFF
. Pure red
is #FF0000
, pure green (which the standard calls lime
) is #00FF00
and pure blue
is #00FFFF
. Note that green
in the standard is defined as #008000
. Figure B.1 contains the XHTML standard color set. Figure B.2 contains the XHTML extended color set.