Update code.py

Use dynamic display sizing so it works on multiple displays.

Author: aioue

CircuitPython_Display_Text/colormask_example/code.py

@@ -15,7 +15,7 @@
 # Make the display context. Change size if you want
 display = board.DISPLAY
 
-background = displayio.Bitmap(320, 240, 1)
+background = displayio.Bitmap(display.width, display.height, 1)
 bg_palette = displayio.Palette(1)
 bg_palette[0] = 0xDDDD00