(It works entirely offline too, you can grab the raw HTML from GitHub and run it locally. No server required or needed.)
If you have any suggestions, feedback, bugs, etc I’d love to know. Also, feel free to take it and build something much better. I licensed this under CC BY-SA 4.0 as I borrowed a little bit of JavaScript from Stack Overflow.
There is a preview that can be expanded at the top after you start with a page title but do you mean a true WYSIWYG interface with all the controls to add for example fonts, tables, images, etc? I don’t even know where I’d start with those.
My bad, sorry. I missed that link. Maybe showing a small preview window would make it more obvious and the page generator more appealing to users at their first visit.
The biggest issue is that you have to close and open the previewer to see your changes.
I’m not sure who your audience is, but if it’s for absolute beginners I would make snippet buttons similar to the BlueFish text editor. This way they can still see how the code works, but don’t need to look up every tag and it’s syntax to start using them.