alt Hacker NewsYes that's why XSLT is such a natural fit when you learn about HTML+CSS. It's the same idea, but applied to HTML templates, which is something you immediately want when you hand-write HTML (e.g. navbars, headers, and footers that you can include on every page).
Your problem here is that you're hand-writing HTML including all the templates. This wasn't a good way to do it 30 years ago and it's not a good way to do it now.
See all these "static site generators" everyone's into these days? We used those in the mid-90s. They were called "Makefiles".