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The CSS guide also got a big reorg. Instead of one giant guide there are now focused guides for color (incl. relative color syntax), typography, motion, responsive design, visual effects, and browser UI theming. Not new guidance, but smaller guides = better retrieval = better output.

Notable updates to existing guides: • exit animations that finish before a dialog closes • light-dark() for images, not just colors • no autocorrect on username and email fields • passkey display names synced via signalCurrentUserDetails() • WebMCP tools that return errors instead of throwing

And the eval numbers. Across 132 tasks (1,124 assertions), pass rates without MWG → with MWG: Claude Code (Sonnet 5): 54% → 87% Antigravity (Gemini 3.8 Flash): 65% → 91% Codex (GPT-5.6): 59% → 81% Same agents, same tasks. The only difference is the guidance.