Looked-up color fails for -fx-background-color in JavaFX CSS file

[Davide Perini]

Hi all,
someone else opened an issue in past on this problem.
I have the exact same problem:
https://mail.openjdk.java.net/pipermail/openjfx-dev/2021-June/030723.html

Kevin closed the issue because it was not able to reproduce but I can 
reproduce it on JavaFX 18.0.1

Can you double check it please?

Thanks
Davide