Chrome, Edge, Firefox and MDN teams release Modern Web Guidance for coding agents

The Google Chrome team, alongside the Microsoft Edge, Mozilla Firefox and MDN teams, published Modern Web Guidance, an Apache-2.0-licensed collection of skills that coding agents load to prefer current web platform features over legacy patterns. The repository includes plugin manifests for Claude, Codex, Cursor, Gemini and Kimi, plus a CLI install wizard and an alternative try-it-out path that feeds curated guidance into an agent's context window. Coverage spans CSS layout such as container queries, subgrid and oklch, performance work, native form and UI components, accessibility, and in-browser AI APIs including translation, summarization and language detection. The code is public on GitHub now.