98.css – A design system for building faithful recreations of old UIs

The Sims https://thesimscss.inbn.dev/

Windows 98 https://jdan.github.io/98.css/

Windows XP https://botoxparty.github.io/XP.css/

Windows 7 https://khang-nd.github.io/7.css/

Edward Tufte https://edwardtufte.github.io/tufte-css/