login.css

#root {
    -fx-background-color:  linear-gradient(lightgray, gray);
    -fx-border-color: white;
    -fx-border-radius: 20;
    -fx-padding: 10 10 10 10;
    -fx-background-radius: 20;

}

#bp {
    -fx-background-color:  linear-gradient(gray,DimGrey );

}

#btnLogin {
    -fx-background-radius: 30, 30, 29, 28;
    -fx-padding: 3px 10px 3px 10px;
    -fx-background-color:       linear-gradient(orange, orangered );
}

#text {
    -fx-fill:  linear-gradient(orange , orangered);
}

Login.java

package sample;


import javafx.application.Application;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.geometry.Insets;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
import javafx.scene.control.PasswordField;
import javafx.scene.control.TextField;
import javafx.scene.effect.DropShadow;
import javafx.scene.effect.Reflection;
import javafx.scene.layout.BorderPane;
import javafx.scene.layout.GridPane;
import javafx.scene.layout.HBox;
import javafx.scene.paint.Color;
import javafx.scene.text.Font;
import javafx.scene.text.FontWeight;
import javafx.scene.text.Text;
import javafx.stage.Stage;
import org.keycloak.admin.client.Keycloak;

/**
 *
 * @web http://zoranpavlovic.blogspot.com/
 */
public class Login extends Application {

    String user = "JavaFX2";
    String pw = "password";
    String checkUser, checkPw;

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

    @Override
    public void start(Stage primaryStage) {
        primaryStage.setTitle("JavaFX 2 Login");

        BorderPane bp = new BorderPane();
        bp.setPadding(new Insets(10,50,50,50));

        //Adding HBox
        HBox hb = new HBox();
        hb.setPadding(new Insets(20,20,20,30));

        //Adding GridPane
        GridPane gridPane = new GridPane();
        gridPane.setPadding(new Insets(20,20,20,20));
        gridPane.setHgap(5);
        gridPane.setVgap(5);

        //Implementing Nodes for GridPane
        Label lblUserName = new Label("Username");
        final TextField txtUserName = new TextField();
        Label lblPassword = new Label("Password");
        final PasswordField pf = new PasswordField();
        Button btnLogin = new Button("Login");
        final Label lblMessage = new Label();

        //Adding Nodes to GridPane layout
        gridPane.add(lblUserName, 0, 0);
        gridPane.add(txtUserName, 1, 0);
        gridPane.add(lblPassword, 0, 1);
        gridPane.add(pf, 1, 1);
        gridPane.add(btnLogin, 2, 1);
        gridPane.add(lblMessage, 1, 2);


        //Reflection for gridPane
        Reflection r = new Reflection();
        r.setFraction(0.7f);
        gridPane.setEffect(r);

        //DropShadow effect
        DropShadow dropShadow = new DropShadow();
        dropShadow.setOffsetX(5);
        dropShadow.setOffsetY(5);

        //Adding text and DropShadow effect to it
        Text text = new Text("JavaFX 2 Login");
        text.setFont(Font.font("Courier New", FontWeight.BOLD, 28));
        text.setEffect(dropShadow);

        //Adding text to HBox
        hb.getChildren().add(text);

        //Add ID's to Nodes
        bp.setId("bp");
        gridPane.setId("root");
        btnLogin.setId("btnLogin");
        text.setId("text");

        //Action for btnLogin
        btnLogin.setOnAction(new EventHandler<ActionEvent>() {
            public void handle(ActionEvent event) {
                Keycloak keycloak = Keycloak.getInstance(
                        "http://localhost:8180/auth",
                        "master",
                        txtUserName.getText().toString(),
                        pf.getText().toString(),
                        "admin-cli");

                    lblMessage.setText("Congratulations " + keycloak.tokenManager().getAccessTokenString());
                    lblMessage.setTextFill(Color.GREEN);

                txtUserName.setText("");
                pf.setText("");
            }
        });

        //Add HBox and GridPane layout to BorderPane Layout
        bp.setTop(hb);
        bp.setCenter(gridPane);

        //Adding BorderPane to the scene and loading CSS
        Scene scene = new Scene(bp);
        scene.getStylesheets().add(getClass().getClassLoader().getResource("login.css").toExternalForm());
        primaryStage.setScene(scene);
        primaryStage.titleProperty().bind(
                scene.widthProperty().asString().
                        concat(" : ").
                        concat(scene.heightProperty().asString()));
        //primaryStage.setResizable(false);
        primaryStage.show();
    }
}