old_contents: """
  Predefined ttk style
  """
  import logging
  from tkinter import ttk
  
  LOGGER = logging.getLogger(__name__)
  
  class TTKStyle(ttk.Style):
      def __init__(self, style_name, **kwargs):
          super().__init__()
          self.configure(style_name, **kwargs)
  
  def init_css():
      TTKStyle('H1.TLabel', font=('Helvetica',32))
      TTKStyle('H2.TLabel', font=('Helvetica',24))
      TTKStyle('H3.TLabel', font=('Helvetica',18))
      TTKStyle('H4.TLabel', font=('Helvetica',16))
      TTKStyle('H5.TLabel', font=('Helvetica',13))
      TTKStyle('H6.TLabel', font=('Helvetica',10))
  
  if __name__ == '__main__':
      import tkinter
  
      root = tkinter.Tk()
      root.wm_title('DEMO - {}'.format(__file__))
      init_css()
      ttk.Label(root, text='H1 header - text size 32', style='H1.TLabel').grid(row=0, column=0, sticky='w')
      ttk.Label(root, text='H2 header - text size 24', style='H2.TLabel').grid(row=1, column=0, sticky='w')
      ttk.Label(root, text='H3 header - text size 18', style='H3.TLabel').grid(row=2, column=0, sticky='w')
      ttk.Label(root, text='H4 header - text size 16', style='H4.TLabel').grid(row=3, column=0, sticky='w')
      ttk.Label(root, text='H5 header - text size 13', style='H5.TLabel').grid(row=4, column=0, sticky='w')
      ttk.Label(root, text='H6 header - text size 10', style='H6.TLabel').grid(row=5, column=0, sticky='w')
      root.mainloop()
  
new_contents: """
  Predefined ttk style
  """
  import logging
  from tkinter import ttk
  
  LOGGER = logging.getLogger(__name__)
  
  class TTKStyle(ttk.Style):
      def __init__(self, style_name, **kwargs):
          super().__init__()
          self.theme_use('alt')
          self.configure(style_name, **kwargs)
  
  def init_css():
      TTKStyle('H1.TLabel', font=('',32, 'bold'), background='white')
      TTKStyle('H2.TLabel', font=('',24, 'bold'), background='white')
      TTKStyle('H3.TLabel', font=('',18), background='white')
      TTKStyle('H4.TLabel', font=('',16), background='white')
      TTKStyle('H5.TLabel', font=('',13), background='white')
      TTKStyle('H6.TLabel', font=('',10), background='white')
      TTKStyle('H1.TCheckbutton', font=('',32), background='white')
      TTKStyle('H2.TCheckbutton', font=('',24), background='white')
      TTKStyle('H3.TCheckbutton', font=('',18), background='white')
      TTKStyle('H4.TCheckbutton', font=('',16), background='white')
      TTKStyle('H5.TCheckbutton', font=('',13), background='white')
      TTKStyle('H6.TCheckbutton', font=('',10), background='white')
      TTKStyle('White.Horizontal.TScale', background='white')
  
  if __name__ == '__main__':
      import tkinter
  
      root = tkinter.Tk()
      root.wm_title('DEMO - {}'.format(__file__))
      init_css()
      ttk.Label(root, text='H1 header - text size 32', style='H1.TLabel').grid(row=0, column=0, sticky='w')
      ttk.Label(root, text='H2 header - text size 24', style='H2.TLabel').grid(row=1, column=0, sticky='w')
      ttk.Label(root, text='H3 header - text size 18', style='H3.TLabel').grid(row=2, column=0, sticky='w')
      ttk.Label(root, text='H4 header - text size 16', style='H4.TLabel').grid(row=3, column=0, sticky='w')
      ttk.Label(root, text='H5 header - text size 13', style='H5.TLabel').grid(row=4, column=0, sticky='w')
      ttk.Label(root, text='H6 header - text size 10', style='H6.TLabel').grid(row=5, column=0, sticky='w')
      root.mainloop()
  
subject: use alt theme and default init_css font family