This is a submission for the Google I/O Writing Challenge
There’s a slightly embarrassing problem that almost everyone using AI coding agents has run into: your agent still codes like it’s 2019.
Ask it to build a modal, and it reaches for a <div> with JavaScript click handlers and messy z-index hacks. Ask it to build a tooltip, and it creates a whole positioning system from scratch. Ask it to add passkey login, and it starts rebuilding things the browser already handles on its own.
This isn't really the agent's fault. It was trained on the entire history of the web: millions of StackOverflow answers, GitHub repos, and old tutorials from a time when <dialog> didn't exist, the Popover API wasn't even a thing, and container queries sounded like science fiction. AI models don't automatically know what's current. They know what's common.
That gap between what's "common" and what's "current" is exactly what Modern Web Guidance, announced at Google I/O 2026, is trying to fix.
