How to make the Label background invisible in tkinter

Question

I am writing a program with python and tkinter that I need to have a Label with invisible bg
How should I do this?
from tkinter import *
win=Tk()
l1 = Label(win, text="hello world!")
l1.place(x=10,y=10)
l2 = Label(win, text="------------")
l2.place(x=10,y=8)
win.mainloop()

enter image description here

As you can see from the image above, l2 is on l1 but bg made this happen but I wanted the "text" to be on l1.