I search the web and didn't find any sulution to help me.
I did tried to check all what that java related in the 'Content Assistent'.
I did tried to add css to the 'File Association', and I do have the JavaFX SDK
Furthermore, it's not detect any css fx property.
This worked for me:
Add javafx sdk library to the java build path
right click on your project -> properties -> Java build path -> libraries -> add library -> javafx sdk
see image 1
Configure e(fx)clipse like your default editor to css files.
windows -> preferences -> general -> editors -> file associations
see image 2