from tkinter import Tk
from tkinter.ttk import Frame, Label, Button

LARGE_FONT = ("Verdana", 12)


class GeoffGUI(Tk):
    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)

        container = Frame(self)

        container.pack(side="top", fill="both", expand=True)
        container.grid_rowconfigure(0, weight=1)
        container.grid_columnconfigure(0, weight=1)

        self.frames = {}

        for obj in (StartPage, PageOne, PageTwo):
            frame = self.frames[obj.__name__] = obj(container, self)
            frame.grid(row=0, column=0, sticky="nsew")

        self.show_frame('StartPage')

    def show_frame(self, cont):
        self.frames[cont].tkraise()


class StartPage(Frame):
    def __init__(self, parent, controller):
        super().__init__(parent)
        Label(self, text="Start Page", font=LARGE_FONT).pack(padx=10, pady=10)
        Button(self, text="Visit Page 1", command=lambda: controller.show_frame('PageOne')).pack()
        Button(self, text="Visit Page 2", command=lambda: controller.show_frame('PageTwo')).pack()


class PageOne(Frame):
    def __init__(self, parent, controller):
        super().__init__(parent)
        Label(self, text="Page 1", font=LARGE_FONT).pack(padx=10, pady=10)
        Button(self, text="Back to Home", command=lambda: controller.show_frame('StartPage')).pack()
        Button(self, text="Visit Page 2", command=lambda: controller.show_frame('PageTwo')).pack()


class PageTwo(Frame):
    def __init__(self, parent, controller):
        super().__init__(parent)
        Label(self, text="Page 2", font=LARGE_FONT).pack(padx=10, pady=10)
        Button(self, text="Back to Home", command=lambda: controller.show_frame('StartPage')).pack()
        Button(self, text="Visit Page 1", command=lambda: controller.show_frame('PageOne')).pack()


app = GeoffGUI()
app.mainloop()