This site uses Inter. Inter is a typeface family optimized for user interfaces and computer screens. It features a tall x-height to aid in readability of mixed-case and lower-case text. Samples and downloads can be found at: rsms.me/inter/. Inter is open-source.
The CSS toolkit is Tachyons. Learn more at tachyons.io.
This website was designed and coded by me. I was heavily inspired by Swiss poster designs.