old_contents: from kivy.app import App
  from kivy.uix.label import Label
  from kivy.uix.boxlayout import BoxLayout
  from kivy.lang import Builder
  
  Builder.load_string(''' #:import hex kivy.utils.get_color_from_hex
  
  <Root>:
      orientation: 'vertical'
      canvas:
          Color:
              rgba: 1, 1, 1, 1
          Rectangle:
              pos: self.pos
              size: self.size
  
      BoxLayout:
          Label:
              canvas.before:
                  Color:
                      rgb: 205.0/255, 220.0/255, 57.0/255
                  Rectangle:
                      pos: self.pos
                      size: self.size
              text: "rgb: 205.0/255, 220.0/255, 57.0/255"
  
          Label:
              canvas.before:
                  Color:
                      rgba: 205.0/255, 220.0/255, 57.0/255, 0.8
                  Rectangle:
                      pos: self.pos
                      size: self.size
              text: "rgba: 205.0/255, 220.0/255, 57.0/255, 0.8"
  
      BoxLayout:
          Label:
              canvas.before:
                  Color:
                      hsv: 66.0/360, 0.741, 0.863  # rgb->hsv conversion required
                  Rectangle:
                      pos: self.pos
                      size: self.size
              text: "hsv: 66.0/360, 0.741, 0.863"
  
          Label:
              canvas.before:
                  Color:
                      rgba: hex('#CDDC39')
                  Rectangle:
                      pos: self.pos
                      size: self.size
              text: "rgba: hex('#CDDC39')" ''')
  
  
  class Root(BoxLayout):
      pass
  
  
  class ColorusageApp(App):
      def build(self):
          return Root()
  
  if __name__ == "__main__":
      ColorusageApp().run()
  
new_contents: from kivy.app import App
  from kivy.uix.gridlayout import GridLayout
  from kivy.lang import Builder
  
  Builder.load_string("""
  #:import hex kivy.utils.get_color_from_hex
  
  <Root>:
      cols: 2
      canvas:
          Color:
              rgba: 1, 1, 1, 1
          Rectangle:
              pos: self.pos
              size: self.size
  
      Label:
          canvas.before:
              Color:
                  rgb: 39/255., 174/255., 96/255.
              Rectangle:
                  pos: self.pos
                  size: self.size
          text: "rgb: 39/255., 174/255., 96/255."
      Label:
          canvas.before:
              Color:
                  rgba: 39/255., 174/255., 96/255., 1
              Rectangle:
                  pos: self.pos
                  size: self.size
          text: "rgba: 39/255., 174/255., 96/255., 1"
      Label:
          canvas.before:
              Color:
                  hsv: 145/360., 77.6/100, 68.2/100
              Rectangle:
                  pos: self.pos
                  size: self.size
          text: "hsv: 145/360., 77.6/100, 68.2/100"
      Label:
          canvas.before:
              Color:
                  rgba: hex('#27ae60')
              Rectangle:
                  pos: self.pos
                  size: self.size
          text: "rgba: hex('#27ae60')"
  """)
  
  
  class Root(GridLayout):
      pass
  
  
  class ColorusageApp(App):
      def build(self):
          return Root()
  
  
  if __name__ == "__main__":
      ColorusageApp().run()
  
subject: use gridlayout and a different color for color usage example