By elements, I don't mean stuff on the periodic table.
I also don't mean the "classic" either. (Fire, water, air, earth)
In my world, the elements are fire, water, plant, and lightning (There's a lot more, as any user can create their own fighting style, but that's irrelevant to the question). When I draw the art in the book, I do draw the elements in the techniques being used (it's an action book, the elemental fighting is essentially the equivalent of a martial art in this world) however, in-world, the elements aren't actually there. They're just visual effects in the book to make it more interesting, but don't actually exist in the world of the book. How could I realistically explain that it doesn't exist, but at the same time acknowledge it's there?
(If this doesn't fit here, please migrate to writing.)