从不同的文件导入小部件样式（类似于css）

Question

我试着用英语写作pyfont.py文件文件到主文件.py. 所以，请帮助我如何访问p.t按钮在这里主文件.py 代码：

mainfile.py
from tkinter import *
from tkinter import ttk


import tkinter as tk

class Login(Frame):


          def __init__(self, master):

                    Frame.__init__(self, master)
                    self.grid()
                    self.create_widgets()
                    self.place(relx=.5, rely=.5, anchor="c")

          def create_widgets(self):
                    self.userLbl = Label(self, text = "UserName")
                    self.userLbl.grid()
                    self.usernameEntry = Entry(self)
                    self.usernameEntry.grid(row = 0, column = 1 ,sticky = W, padx=(50,50), pady=(20,20))
                    self.passwrdLbl = Label(self, text = "Password")
                    self.passwrdLbl.grid(row = 1, column = 0 ,sticky = W, padx=(50,50), pady=(20,20))
                    self.passEntry = Entry(self, show="*")
                    self.passEntry.grid(row = 1, column = 1 ,sticky = W, padx=(50,50), pady=(20,20))
                    self.submit_bttn = ttk.Button(self, text = "Login",  style="p.TButton")
                    self.submit_bttn.grid(row = 2, column = 1 ,sticky = W, padx=(50,50), pady=(50,50))


# main
root = Tk()
root.title("Login")
root.geometry("800x400")
app = Login(root)
root.mainloop()


pyfont.py file

import tkinter
from tkinter import ttk

style1 = tkinter.ttk.Style()
style1.configure("BW.TLabel", foreground="black", background="white")

style1.configure("BW.TButton", foreground="red", background="white")

style1.configure("p.TButton", foreground="yellow", background="white")

此代码处于运行状态，但样式没有反映在botton上。在此方面的任何帮助都将不胜感激。你知道吗