Mitch, instead of using your script, add this to the "Extra Properties" section of the Style you want to turn upside-down.
This will allow users to turn OFF the upside-down by selecting a different style.
You could also just duplicate your main style, add this to it and call it "main upside-down" or whatever. Then set that as the default style for the day
dont forget to reset your default style to the correct one when you're done having fun.