The reason for css additions came from the fact that I was not pleased with how most browsers show my html writings. For example, I want most of the "<P>"aragraphs to be "justified" aligned on both sides, and in many occasions a little indented. However, that should not be for all the paragraphs - only those with prosaic text.
The modern html spec allows for a "class" attribute which does even allow to simulate an xml view view "<span>" tags. Which is inconvenient since pure xml as source files does not allow us to use any html browser for a preview of our "htm" source files. So, let's restrict to html tags and make for an easy way to add "class" hints that point to a definition in the css block of the sitefile.