This is something I did for our DnD group, the map was created collectively in a photo editing tool and then split up with MapTiler (https://www.maptiler.com/) which generates HTML/CSS/JS you can throw up on a server I have here: http://maps.opendnd.org/ao/. The main issues I found are some skewing from the original map and some pretty bad pixelation when you get to some of the lower levels. That could all be remedied with a better vector graphic for the map -- something to work on in the future.