A DESCRIPTION OF THE PROBLEM :
The present CSS implementation accepts 3 digits and 6 digits hex coded Color :
With the CSS 1 convention : #rgb must be interpreted as #rrggbb.
With 4 and 5 digits, last missing digits are replaced with 0 (This is not a CSS recommendation)

Then #f0a is interpreted as #ff00aa opaque Color.
And #f00a is interpreted as #00f00a opaque Color.

I request to reach CSS Color Level 4 recommendation which accepts 3, 4, 6 and 8 digits.
With the following conventions :
- #rgb must be interpreted as #rrggbb opaque Color.
- #rgba must be interpreted as #rrggbbaa Color with an aa Alpha value.
- #rrggbb must be interpreted as #rrggbb opaque Color.
- #rrggbbaa must be interpreted as #rrggbbaa Color with an aa Alpha value.

I can provide such implementation. Details and the code to test the present implementation at https://github.com/scientificware/jdk/issues/13.