Ah, I found the line that I believe covers it. In ...
# tornadofxr
Ruckus
09/04/2018, 5:48 PMAh, I found the line that I believe covers it. In the CSS Ref under "Limitations", item 4:
The structural pseudo‑classes are not supported.https://docs.oracle.com/javase/8/javafx/api/javafx/scene/doc-files/cssref.html#introlimitations