cdnjs is a free distributed JS library delivery service.
HTTP Strict Transport Security (HSTS) informs browsers that the site should only be accessed using HTTPS.
Hugo is an open-source static site generator written in Go.
MathJax is a cross-browser JavaScript library that displays mathematical notation in web browsers, using MathML, LaTeX and ASCIIMathML markup.
Open Graph is a protocol that is used to integrate any web page into the social graph.
Twitter is a 'microblogging' system that allows you to send and receive short posts called tweets.
Vercel is a cloud platform for static frontends and serverless functions.