If you can't go through a CS curriculum with it then it isn't coding? Maybe that's the distinction.
Yet I do see your point and there's probably nothing horrible about using it in your title. "Learn HTML and CSS Markup" may have been a better title, possibly even from an SEO perspective.
Again, not trying to be pedantic. Not a big deal. No data structures were harmed in the making of this title.
BTW, that aside, this nicely done. I am going to have my son go through it.
But that would also make things like basic SQL 'not coding', and any program you wrote where you didn't use an arbitrarily long loop.
That makes "print('Hello world')" not coding, and then it becomes clear that you're drawing an arbitrary line in the sand. "If you aren't writing compilers, you're not coding" or some such nonsense.
HTML and CSS are languages for encoding the semantics of webpage formatting and content. They are domain specific languages. They are not turing complete. But they are coding.