Tkinter askcolor function isn't changing the background colour of the frame

I am making an expense tracker as a fun project. I have encountered an issue where the colour choosing method I am using inside the frame class isn't working, could someone help please?

Here is my code:

import tkinter as tkfrom tkinter import ttk, colorchooser, messageboxclass ExpenseTracker(tk.Tk):    def __init__(self):        super().__init__()        self.title("Expense Tracker")        self.geometry("700x700")        self.minsize(700, 700)        self.login = Login(self)        self.mainloop()class Login(tk.Frame):    def __init__(self, parent):        super().__init__(parent)        tk.Label(text="Enter Username:").place(relx=0.5, rely=0.36, anchor=tk.CENTER)        tk.Label(text="Enter Password:").place(relx=0.5, rely=0.46, anchor=tk.CENTER)        change_colour = tk.Button(text="Background Colour", command=self.change_colour)        change_colour.place(relx=0.9, rely=0.1, anchor=tk.CENTER)        username_entry = tk.Entry()        username_entry.place(relx=0.5, rely=0.4, anchor=tk.CENTER)        password_entry = tk.Entry()        password_entry.place(relx=0.5, rely=0.5, anchor=tk.CENTER)        login_box = tk.Button(text="Login")        login_box.place(relx=0.5, rely=0.55, anchor=tk.CENTER)        self.grid()    def change_colour(self):        color = colorchooser.askcolor()[1]        self.configure(bg=color)ExpenseTracker()

At first, the login class inherited from "ttk.Frame", which I wanted but I was getting an " unknown option "-bg"" error. Then, I changed it to inherit from "tk.Frame", which stopped the error from happening, but the background still doesn't change when I use the change colour button.