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

Also worth checking out: https://botoxparty.github.io/XP.css and https://khang-nd.github.io/7.css

THANK you so much for the XP one. XP's UI is my favorite of all the Windows UIs. It had just enough modernity to feel sleek but still had contrast to be easily seen and read and understood.

Windows 7 UI was a bit too flashy and employed looks over readability and Windows 98 was too old fashioned and also suffered from a lack of contrast with all the grey.