I used the WYSIWYG HTML editor called Mozilla Composer. It was very simple as long as you just want text, images, lists, tables, and links (no CSS nonsense or ECMAScript). It looks like the latest iteration is Nvu (pronounced "N-view").
https://en.wikipedia.org/wiki/Mozilla_Composer
You can see an example of the result here:
http://instrumentation.conlang.org/instwork.html
I haven't actually used Nvu, but it's here:
http://www.nvu.com/
@Ralph From reading through the Wikipedia page, Nvu was an active project from 2004 to 2005, then shelved in favor of KompoZer, which was an active project until 2010.
SeaMonkey is still an active project and includes Seamonkey Composer, a descendant of Mozilla Composer.
https://www.seamonkey-project.org/