Google released an AI “skill” at Google I/O last month called Modern Web Guidance. It’s essentially a folder of nested Markdown files that AI agents know how to read and use as part of their context window when they deem appropriate. This skill has a bunch of HTML/CSS/JavaScript information that guides AI to, hopefully, do a much better job at these languages than even high-power models do alone (because there is always a time-and-training gap between platform releases and model updates).
Honestly I’ve found it to do a pretty good job, handling things like fallbacks and user preferences (e.g. prefers-reduced-motion) well, which is too easily forgotten. Check out this Markdown file, which essentially explains (in AI-speak) how to do what I taught you to do (in Human-speak) in my series In-N-Out Animations. I’m not going to vouch for it producing perfect and accessible code every time or anything foolish like that. You should know what you’re doing.