from tkinter import ttk  # Normal Tkinter.* widgets are not themed!
from ttkthemes import ThemedTk

window = ThemedTk(theme="equilux")
frame1 = ttk.Frame(window)
but1 = ttk.Button(frame1, text="Quit", command=window.destroy).pack()
frame2 = ttk.Frame(window)
but2 = ttk.Button(frame2, text="Quit", command=window.destroy).pack()
but3 = ttk.Button(frame2, text="Quit", command=window.destroy).pack()
frame1.pack()
frame2.pack()
window.mainloop()