CSS not finding JavaFX rules

问题

I am currently trying to style my JavaFX project with CSS, and each time I try to implement a property, it says "no rule for ___ found!". I have tried -fx-font-family: and -fx-background-color:.

I am using Eclipse 2019-09.

EDIT: Minimal Reproductive Example: application.css in a JavaFX project in Eclipse 2019-09

.label { -fx-font-family: Helvetica; }

Shows the message "no rule for -fx-font-family found!" and underlines the -fx-font-family line in yellow.

来源：https://stackoverflow.com/questions/59338602/css-not-finding-javafx-rules