@Override
    public void paintComponent(Graphics g) {
        super.paintComponent(g);
        int w = getWidth();
        int h = getHeight();
        g.setColor(selected ? Color.yellow : (color == Side.WHITE) ? DARKBROWN
                : LIGHTBROWN);
        g.fillOval(0, 0, w, h);
        g.setColor((color == Side.WHITE) ? LIGHTBROWN : DARKBROWN);
        g.fillOval(4, 4, w - 8, h - 8);
    }