Navigating to htmlpreview.github.com 404s - link should of course now be the awesome htmlpreview.github.io
please update your links to use htmlpreview.github.io instead. Subdomains of github.com are deprecated for GitHub Pages. They will not redirect to github.io after April 15, 2021.
Navigating to htmlpreview.github.com 404s - link should of course now be the awesome htmlpreview.github.io