activebackground = darker_than_bg
activeforeground = txt_color
relief = sunken
insertbackground = txt_color
relief = flat
(and a line below entry widget to make it visible)
highlightbackground=bd_color
highlightthickness=bd_thickness
highlightbackground=bd_color
highlightthickness=bd_thickness
from tkinter import ttk
s = ttk.Style()
s.theme_use('clam')
s.configure("grey.(Orientation).TProgressbar", background=fg, bordercolor=fg,
troughcolor=bg, lightcolor=fg,darkcolor=fg)
progressbar = ttk.Progressbar(kw, style="grey.(Orientation).TProgressbar")