To nitpick a bit, I'd say there is something that is "placed outside the stylesheet".

Now, arguably it's not a "number or word that appears in the output", that's true, but it is a part of the logic of FizzBuzz. It's the fact that there are 100 and exactly 100 <li> elements in the HTML part.

I mean, it wouldn't be a correct FizzBuzz without precisely that HTML. Having exactly 100 <li> elements is implementing the part of the logic that a. loops, and b. stops at 100.

But of course this is just nitpicking, as I said ;)

HTML is just the runtime of CSS