So i am not sure if i did anything wrong or if it is the code but i followed your installation and get the red box at the top but i can't find any buttons (i think the words "Melee"/"Ranged" are meant to be changed to them?).
I changed content.js and it should work now. When I tidied up the code to make it more readable I made it only work for the obscure rarely used stat block format they have rather than their common type. Sorry!
So i am not sure if i did anything wrong or if it is the code but i followed your installation and get the red box at the top but i can't find any buttons (i think the words "Melee"/"Ranged" are meant to be changed to them?).
I tested this on several links:
This is what information i get from the extension. If you need something specific to fix this just tell me.