如何摆脱Jframe底部和右侧的白色1PX线？

Question

我想要一个jpanel，该目前是黑色的，但会在jframe内更改颜色。我只设置了面板的大小，然后在我的框架上调用.pack，但是我框架的底部和右侧出现了一条丑陋的白色1PX线。为什么那是这样，我该如何修复？ 我目前正在运行Windows 11。

import javax.swing.JFrame;

public class Main {
    
    private static GamePanel gamePanel;

    public static void main(String[] args) {
        
        createWindow();
        
        gamePanel = new GamePanel();
        window.add(gamePanel);
        
        window.pack();
        window.setLocationRelativeTo(null);
        window.setVisible(true);
        
    }
    
    private static JFrame window;
    
    private static void createWindow() {
        window = new JFrame();
        window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        window.setTitle("My Game");
        window.setResizable(false);
    }
    
}

import java.awt.Color;
import java.awt.Dimension;
import javax.swing.JPanel;

public class GamePanel extends JPanel {
    
    // Screen settings
    final int originalTileSize = 16;
    final int scaleFactor = 3;
    
    final int tileSize = originalTileSize * scaleFactor;
    final int maxScreenCol = 16;
    final int maxScreenRow = 12;
    final int screenWidth = maxScreenCol * tileSize;
    final int screenHeight = maxScreenRow * tileSize;
    
    // --- Constructor ---
    GamePanel () {
        this.setPreferredSize(new Dimension(screenWidth, screenHeight));
        this.setBackground(Color.black);
        this.setDoubleBuffered(true);
    }
    
    public int getScreenWidth () {
        return screenWidth;
    }
}