I use Markdown and HTML, CSS, and Python (just stdlib, no packages) to generate static files. I think that will last just about the same length of time.
Admittedly I need a Makefile, and Make is pretty impoverished for this use, and I want to replace it with something else. Shell isn't quite good enough because I don't want to rebuild the entire site on every edit, and I don't want to remember which files to rebuild. http://www.oilshell.org/site.html
I use something very similar on my website, except with a few twists - MultiMarkdown (instead of Markdown) for HTML, Perl for piping MultiMarkdown produced HTMLs through some regex changes, and redo instead of Make for rebuilds.
I've seen redo (and talked with apenwarr about it) although I think my brain is still stuck on static/declared dependencies. That doesn't apply to every problem but it definitely applies to a blog.
Is your build parallel? That's one of my main requirements. I'd be interested in seeing the redo files if they're public.
My website is probably a lot simpler than yours. All the "do" files are at the root level. But I have to state that there is no "redo" syntax really. You just take the scripts that do things and save them to files with a "do" extension.
http://www.oilshell.org/blog/
Markdown is a significant win, and CommonMark made it a lot better.
CommonMark is a Useful, High-Quality Project http://www.oilshell.org/blog/2018/02/14.html
Admittedly I need a Makefile, and Make is pretty impoverished for this use, and I want to replace it with something else. Shell isn't quite good enough because I don't want to rebuild the entire site on every edit, and I don't want to remember which files to rebuild. http://www.oilshell.org/site.html