import tkinter

canvas = tkinter.Canvas()
canvas.pack()

sirka = 50
vyska = 20
trif = ["blue", "red", "green"]
for i in range (3):
    farba = trif[i]
    canvas.create_rectangle(sirka+400, 280+vyska, 400-sirka, 260+vyska)
    sirka -= 20
    vyska -= 20

sirka = 100
vyska = 10

while sirka>0:
    r = random.randrange(256)
    g = random.randrange(256)
    b = random.randrange(256)
    farba = f"#{r:02x}{g:}{b:}