To use the theme just create a style, import the azure.tcl, or the azure-dark.tcl file, and call the theme_use method to set the theme:

# Create a style
style = ttk.Style(root)

# Import the tcl file
root.tk.call('source', 'azure.tcl / azure-dark.tcl')

# Set the theme with the theme_use method
style.theme_use('azure / azure-dark')

Azure theme has a style for every ttk widget, but there are some new widget styles, such as an accent button, toggle switch, and toggle button. You can apply these with the style option

If you need a highlighted button, use AccentButton:

button = ttk.Button(root, text='AccentButton', style='AccentButton', command=callback)

To create a ToggleButton you need a checkbutton, to which you can apply the ToggleButton style:

togglebutton = ttk.Checkbutton(root, text='ToggleButton', style='ToggleButton', variable=var)

The use of switches is becoming more common these days, so this theme has a Switch style, that can be applied to checkbuttons:

switch = ttk.Checkbutton(root, text='Switch', style='Switch', variable=var)

import tkinter as tk
from tkinter import ttk

root = tk.Tk()

# Create a style
style = ttk.Style(root)

# Import the tcl file
root.tk.call('source', 'azure.tcl')

# Set the theme with the theme_use method
style.theme_use('azure')

# A themed button
button = ttk.Button(root, text='I\'m a themed button')
button.pack(pady=20)

root.mainloop()

• If you don't use Windows, the default font for tkinter (TkDefaultFont) can be a bit ugly in the theme, so I recommend to you use tkextrafont, which is great if you want to use an .ttf file without installing (I use Arial for it and recommend this to everyone)
• Performance issue:
  If you put a widget inside a LabelFrame, the hover rendering can be extra slow (the same goes for Notebook)

• Flat, rounded elements, high contrast
• Colors: blue #007fff #3398ff, gray #e6e6e6 #cccccc #999999 #737373 #333333 and of course #ffffff #000000 #ff0000