> LLMs are also terrible at these new standards. If they even know about them, they often think they're not baseline yet…

It doesn’t have to be that way.

You could create a Skill [1] that tells the agent to use modern css; the newer models like Opus 5 are probably much better with modern css.

Google released a set of skills at I/O called Modern Web Guidance [2] that steer coding agents to use modern css and best practices.

[1]: https://www.skills.sh/paulirish/dotfiles/modern-css

[2]: https://developer.chrome.com/docs/modern-web-guidance/get-st...