Change background color of all ScrollPanes defined by class

Question

I am trying to change the background of a all ScrollPanes that are defined by my MethodScrollPane class:

package Opmaak.Interfaces.Panes;

import Opmaak.Var;
import javafx.scene.Node;
import javafx.scene.control.ScrollPane;
import javafx.scene.layout.Background;
import javafx.scene.layout.BackgroundFill;

public class MethodScrollPane extends ScrollPane {
    public MethodScrollPane(Node content) {
        super();
        setHbarPolicy(ScrollPane.ScrollBarPolicy.NEVER);
        setFitToWidth(true);
        setStyle("-fx-background-color:transparent;");
        setContent(content);

    }
    public void setBackgroundMethodScrollPane() {
        setBackground(new Background(new BackgroundFill(Var.color, null, null)));
    }
    
}

But how can I achieve this when I change the variable Var.color? I just can't seem to find a solution.

Here's my Var class if it is needed:

package Opmaak;

import javafx.scene.paint.Color;

public class Var {
    public static double stageHeight;
    public static double stageWidth;
    public static Color color;

    public static boolean colorChange = false;
    public static void setColor(Color color) {
        Var.color = color;

        // Here I want to change the background of the MethodeScrollPanes
        RootPane.setBackgroundColorRoot();
    }
}