If you want a fancy multi-user site, the source code for archiveofourown.org is on github or gitlab (idr which). But for a small single user site I’d just go static. You could go full nerdy and write in texinfo then run an html converter. Texinfo is actually for computer manuals so it has chapters, sections, cross references, indexes, link navigation between pages, the whole bit. It is a markup language which I think is better than a wysiwyg formatter for documents that will be read in more than one way. I think there is a way to make epubs from texinfo docs.
In a sort of similar spirit there is Org mode (org-mode.org) but you have to be or become an Emacs zealot to use it.
Look also at pandoc.org which converts between lots of formats.