Bind Font Size in JavaFX?

Just put everything where you want the fontsize to change in a container and set that style or use bindings if you want.

import javafx.application.Application;
import javafx.beans.binding.Bindings;
import javafx.beans.property.DoubleProperty;
import javafx.beans.property.IntegerProperty;
import javafx.beans.property.SimpleDoubleProperty;
import javafx.beans.property.SimpleIntegerProperty;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
import javafx.scene.control.TextArea;
import javafx.scene.layout.HBox;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;

public class FontBind extends Application {

    private DoubleProperty fontSize = new SimpleDoubleProperty(10);
    private IntegerProperty blues = new SimpleIntegerProperty(50);

    @Override
    public void start(Stage primaryStage) {
        Button btn = new Button("click me, I change color");
        btn.setOnAction((evt)->{blues.set(blues.get()+20);});//max?
        Label lbl = new Label("I'm a label");
        TextArea ta = new TextArea("Lots of text can be typed\nand even number 1234567890");
        HBox hbox = new HBox(new Label("I never change"));
        VBox child = new VBox(btn, lbl, ta);
        VBox root = new VBox(child, hbox);
        Scene scene = new Scene(root, 300, 250);

        fontSize.bind(scene.widthProperty().add(scene.heightProperty()).divide(50));
        child.styleProperty().bind(Bindings.concat("-fx-font-size: ", fontSize.asString(), ";"
                                                  ,"-fx-base: rgb(100,100,",blues.asString(),");"));

        primaryStage.setTitle("Hello World!");
        primaryStage.setScene(scene);
        primaryStage.show();
    }

    public static void main(String[] args) {
        launch(args);
    }

}

I’m not sure what your style is already bound to, but you’re allowed to set multiple css values in the style string.