JTextField의 배경색이 적용되지 않는 버그?

import java.awt.*;
import javax.swing.*;
 
public class BackgroundColorTest extends JFrame {
    {
        try {
            UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
 
    public static void main(String[] args) {
        BackgroundColorTest frame = new BackgroundColorTest();
        JTextField textField = new JTextField();
 
        frame.getContentPane().setLayout(null);
        frame.getContentPane().setPreferredSize(new Dimension(200, 40));
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.add(textField);
        textField.setBounds(0, 0, 200, 40);
        textField.setBackground(Color.red);
        frame.pack();
        frame.setVisible(true);
    }
}