section {display:none}
section:target {display:block}
I would also make it so the url was example.com/#/pageid, so the id is "/pageid". Looks a bit better I think.
I was thinking in using it for a blog, but I am afraid of having everything in a single file, and that making some mistake will render the whole site useless.
Also not sure how hard would be to manage once it starts to grow... Maybe it needs to grow significantly more than I can before this is a road block.
If you don't want to use a static site generator I think you're better off with just html files for each page/blog entry, or you could use something like htmx and load stuff in that way.
Pro-tips: switch styles to show all content (and buttons) then use contenteditable - for the whole page or allow it at element levels, allow copying/removing specific element ("template"), POST new version, HTTP Authenticated, to the server or just save :)
https://john-doe.neocities.org/
I am not html expert, so I have no idea how complicate or what implications would that have.