TheMadExile is 100% correct.
I took the time to do a deep dive into Harlowe. It can do what you need it to. Particularly, the last two sections in the following link may prove useful for you to setup HTML canvas code.
Harlowe: thinking outside the (box:)
That said, many here would argue that SugarCube is the most robust format to work in. If you like Harlowe, then continue with it. If you are having second thoughts, check out SugarCube. If you are hardcore, Snowman. 