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.
OpenResty is a web platform based on nginx which can run Lua scripts using its LuaJIT engine.
Progressive Web Apps (PWAs) are web apps built and enhanced with modern APIs to deliver enhanced capabilities, reliability, and installability while reaching anyone, anywhere, on any device, all with a single codebase.
W3.CSS is a CSS framework developed by the World Wide Web Consortium (W3C), the main international standards organisation for the World Wide Web.