Google Chrome releases Modern Web Guidance 1.0 skills for coding agents

Google’s Chrome for Developers team highlighted the 1.0 release of Modern Web Guidance on 13 November 2026 after the open-source project reached number one on GitHub Trending within 48 hours of its 11 November launch. Maintained jointly by contributors across Google Chrome, Microsoft Edge, Mozilla Firefox, MDN and the web community, the package embeds token-efficient documentation and Baseline compatibility data into Claude Code, Antigravity CLI, GitHub Copilot CLI, Vercel Agent Skills and Chrome DevTools for agents.

Interactive npx installer, legacy-scan audits and benchmark curation

Developers run npx modern-web-guidance@latest install to configure supported coding agents interactively, query targeted guides covering View Transitions, container queries, CSS subgrid, oklch colour spaces, top-layer dialog animations and scrollbar-color via search and retrieve subcommands, or audit an existing project using npx modern-web-guidance@latest legacy-scan.

Maintainers author and test rules inside github.com/GoogleChrome/modern-web-guidance-src against an evaluation dashboard at googlechrome.github.io/modern-web-guidance-src, pruning basic boilerplate that models already generate accurately while targeting modern browser primitives that LLMs routinely replace with outdated JavaScript libraries.

Technical details

CLI commands

npx modern-web-guidance@latest install, search, retrieve and legacy-scan

Governance and licence

Apache 2.0 open-source collaboration across Google Chrome, Microsoft Edge, Mozilla Firefox and MDN

Supported agent toolchains

Claude Code, Antigravity CLI, GitHub Copilot CLI, Vercel Agent Skills and Chrome DevTools MCP

Source and build split

Authoring and evals in GoogleChrome/modern-web-guidance-src; compiled skills in modern-web-guidance

Release details & context

Two-repository evaluation pipeline and token budget discipline

Unlike static prompt rules pasted into a project README, Modern Web Guidance splits rule authoring in GoogleChrome/modern-web-guidance-src from the compiled distribution package in GoogleChrome/modern-web-guidance so every candidate topic is scored before versus after skill injection.

Topics where frontier models already emit modern HTML and CSS without assistance are excluded to preserve context-window budget, keeping retrieval focused on newer Baseline specs such as discrete top-layer entry and exit animations, text-wrap balance and native popover positioning.

Common questions

Is Modern Web Guidance 1.0 restricted to Chromium-only APIs?

No, the project is co-authored with Microsoft Edge, Mozilla Firefox and MDN teams around cross-browser Baseline compatibility data rather than single-engine extensions.

How can teams check an existing frontend repo for outdated polyfills using Modern Web Guidance?

Running npx modern-web-guidance@latest legacy-scan inspects the project for legacy patterns that have native HTML, CSS or browser API replacements.

Google release timeline (30 launches tracked)

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