PDF::Writer：Color::CSS[]

everyday Ruby 
require 'color/css'

p Color::CSS["Black"]
p Color::CSS["Blue"]
p Color::CSS["Red"]
p Color::CSS["RED"]
p Color::CSS["red"]

で、

#<Color::RGB:0x401b601c @b=0.0, @g=0.0, @r=0.0>
#<Color::RGB:0x401b5e8c @b=1.0, @g=0.0, @r=0.0>
#<Color::RGB:0x401b0bbc @b=0.0, @g=0.0, @r=1.0>
#<Color::RGB:0x401b0bbc @b=0.0, @g=0.0, @r=1.0>
#<Color::RGB:0x401b0bbc @b=0.0, @g=0.0, @r=1.0>