well I've had it for over two years now, so I guess that long! it was a gradual unplanned growth, I never anticipated making so many pages myself ^^ definitely start small and don't try to give yourself overwhelming goals. go one page at a time :3
Notepad++ is great but I use Visual Studio Code right now, its search and replace feature works across multiple files if you need it
Big update!! my new rendition of my rainbow science pages has its own domain!! it is also now organized better, has more diagrams and info!
i wil be updating my old rainbow pages with a disclaimer and links to the new pages :3