How to create two frames (top and bottom) that have the same height, using Tkinter?

In Tkinter Python, I want to create two frames and place one on top of the other, and then insert a matplotlib plot inside each of these two frames. That, I managed to do. The problem is that, when created, these two frames always seem to have different heights (the bottom one is always smaller than the top one).

My goal is to get the two frames to have the same height.

Here's a simplified version of the code that produces the said undesirable result :

import tkinter as tkfrom matplotlib.backends.backend_tkagg import FigureCanvasTkAggimport matplotlib.pyplot as pltimport numpy as np# Rootroot = tk.Tk()root.state('zoomed')# Upper frame canv = tk.Frame(root)canv.pack()plt.rcParams["axes.prop_cycle"] = plt.cycler(color=["#4C2A85", "#BE96FF", "#957DAD", "#5E366E", "#A98CCC"])plt.style.use('ggplot')L = [i for i in range(10)]fig, ax = plt.subplots()l = ax.fill_between(L, L)ax.set_title("Upper plot")canvas = FigureCanvasTkAgg(fig, canv)canvas.draw()canvas.get_tk_widget().pack()# Lower frame canv2 = tk.Frame(root)canv2.pack()fig2, ax2 = plt.subplots()l2 = ax2.fill_between(L, L)ax2.set_title("Lower plot")canvas2 = FigureCanvasTkAgg(fig2, canv2)canvas2.draw()canvas2.get_tk_widget().pack()root.mainloop

Thanks to anyone willing to help.