rootPanel.css

.rootPane {

    -fx-border-insets: 23;
    -fx-background-insets: 23;
    -fx-background-radius: 6;
    -fx-border-radius: 6;
    -fx-border-color: gray;
    -fx-border-style: solid;
    -fx-border-width: 1;
    -fx-effect: dropshadow(three-pass-box, rgba(100, 100, 100, 1), 24, 0.5, 0, 0);
}