I think you need to use the already defined methods for color displaying changes:
absence - empty red line
appearance - green text
change - old in red and new in green

example: https://lh3.googleusercontent.com/proxy/v2OKdeAj5p7RGjMA-jZy6OfKgFElXNdiGlbquhlV8-rJYleaMX_eXhOvfEq7SKlMD1xsTu5kEsfLc4uIc18-20pxwodYADfuIZruQQ