How to make my Tkinter app fit the whole window no matter the size?

I made a Tkinter app using Python. I want it to auto-resize and fill the whole window no matter how I resize it. The problem is that when I expand the window size (using my cursor), grey space appears on the borders to fill the gaps (see the image below).

Grey space filling

Here is the code minus the unnecessary details :

import tkinter as tk
from tkinter import ttk
import openpyxl


root = tk.Tk()

frame = ttk.Frame(root)
frame.pack()

widgets_frame = ttk.LabelFrame(frame, text = "Insert Data")
widgets_frame.grid(row = 0, column = 0, padx = 20, pady = 10)

day_label = ttk.Label(widgets_frame, text = "Date")
day_label.grid(row = 1, column = 0, padx = 5, pady = (0, 5), sticky = "ew")
day_entry = ttk.Entry(widgets_frame)
day_entry.grid(row = 2, column = 0, padx = 5, pady = (0, 5), sticky = "ew") 

walking_entry = ttk.Entry(widgets_frame)
walking_entry.insert(0, "Walking duration (min)")
walking_entry.bind("<FocusIn>", lambda e: walking_entry.delete('0', 'end'))
walking_entry.grid(row = 3, column = 0, padx = 5, pady = (0, 5), sticky = "ew")

button = ttk.Button(widgets_frame, text = "Insert")
button.grid(row = 4, column = 0, padx = 5, pady = 5, sticky = "nsew")

treeFrame = ttk.Frame(frame)
treeFrame.grid(row = 0, column = 1, pady = 10)
treeScroll = ttk.Scrollbar(treeFrame)
treeScroll.pack(side = "right", fill = "y")

cols = ("Day", "Walking")

treeview = ttk.Treeview(treeFrame, show = "headings", yscrollcommand = treeScroll.set, columns = cols, height = 13)
treeview.column("Day", width = 100)
treeview.column("Walking", width = 50)
treeview.pack()
treeScroll.config(command = treeview.yview)

root.mainloop()

Does anybody have a suggestion that would help me solve this issue ? Thanks.

I added this line of code because, in another thread, they said it helps with expanding the widgets equally when the window size increases :

root.grid_columnconfigure(0,weight = 1)
root.grid_columnconfigure(1,weight = 1)
root.grid_rowconfigure(0, weight = 1)
root.grid_rowconfigure(1, weight = 1)
root.grid_rowconfigure(2, weight = 1)
root.grid_rowconfigure(3, weight = 1)
root.grid_rowconfigure(4, weight = 1)

Unfortunately, even after doing so, I didn't notice any changes.

You could use expand = True, fill = BOTH as an attribute for the required widgets to expand them to full size.