I am using Netbeans. I don't know what I'm doing wrong and I'll detail what I've done in sections within the attached image:
Rename theme.res to theme_legacy.res
Delete indicated file and folders.
In the designer create the constant "theme" and save file.
Rename resource file in main class and save file.
Activate CSS file and save.
In section 6 it shows the incomplete CSS file. After executing the project another "theme" is created as shown in section 7.

I appreciate your comments.