See the tokenization and characters sections of CSS and the first Unicode panel.
This should not be red.
This should be aqua.
This should be blue.
This should be fuchsia.
This should be gray.
This should be green.
This should be lime.
This should not be red.
This should be maroon.
This should be navy.
This should be olive (and browsers that don't support character escapes should get this).
This should probably not be red.
This should be silver.
This should be yellow.
This should not be red.
This should be green.
This should be purple.
This should be maroon (according to the CSS2 errata).
This should not be red.
This should be blue.
This should be maroon.
(Back to CSS Testing Information, David Baron)