Can't Create A 100x100px Window

I have an assignment to create a circle with a radius of 40px in a 100px by 100px window and move the circle with the arrow keys.The circle can't move past the the edges of the window. I believe I have the code right but the window won't create the window or pane with a width of 100 px because of the close, minimize, maximize buttons. Is there a way to remove those or force JavaFX to create it with a width of 100px? Here's what I've got so far.

package movecircle;

import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.layout.Pane;
import javafx.scene.paint.Color;
import javafx.scene.shape.Circle;
import javafx.stage.Stage;

[code]....