cssnext allowed developers to use tomorrow's CSS syntax today, transpiling futuristic CSS features into browser-compatible code. It was a powerful preprocessor for experimenting with upcoming CSS standards. While deprecated in favor of PostCSS plugins and Preset Env, cssnext provided a comprehensive solution for exploring and incorporating advanced CSS functionalities into web projects, streamlining development and empowering developers to adopt future-proof styling techniques. Its approach has significantly influenced modern CSS tooling.