Aside my web involvement I did a lot of print design as well. For print wysiwyg is perfectly fine.
But how would you wysiwyg for a medium that is inherently multifaced? I mean your window could be small, or huge, portrait or landscape, it could have colors or not, heck it could even be print.
So you won't get what you see unless you replicate the exact conditions under which it was seen when tou made it. Do you want that thing that you scale to stay at fixed size, should it stay at fixed distances to the viewport borders? If yes which ones? What happens if users set their font sizes differently and your perfectly scaled text box overflows? Either that wysiwyg editor has very opinionated choices that won't work for half of the people, or it will have auch a complexity in its options you will be better off with learning css in the first place.
Web is not print, nobody will get what you see.
That being said, if you are really just about content, I would just use the most basic default browser css (so basically none) and html and call it a day. That won't look shiny, but if people want shiny they can do their own styling. Some of my favourite blogs do this.
Other than that I wouldn't discount the fact that a backend can be a crucial part of the content as well as it allows you to do valuable things that are geared towards the consumption of said content, e.g. taxonomy (tags, categories, authors, consistent dates), but also more specialized things like linking between relevant topics, etc.
Of course you could also do that by hand, but then you wouldn't be focusing on the content, wouldn't you?
In the end it is your content and you want to present it in a certain way. If you want precise control over the how, you have to deal with these things — if it ia just about the content, use whatever CMS you like and never look back.
It is doable, but it requires a stable runtime. Just the HTML/CSS ecosystem is too flaky, and HTML/CSSS is a poorly design system for this type of interactive systems/apps.
1997 calling, they say they have that wysiwyg tool you’ve been waiting for.