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Modern Web Guidance v0.0.192 is out. With it your coding agent now knows how to: • build SMS one-time-code forms that autofill (WebOTP) • make dark mode toggles that follow the OS • honor the OS text size setting • reduce INP and lazy-load video/audio • feature-detect CSS at-rules with @supports

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.

Credits for this release: dark mode toggle, @supports, CSS reorg by @lea.verou.me INP + media lazy-loading by @malchata.bsky.social WebOTP + passkey updates by @agektmr.com OS text scale by @sturobson.com exit animations by me WebMCP by François Beaufort and Kasper Kulikowski

Also removed: 3 Cross-Origin Storage guides introduced in v0.0.191. @jakearchibald.com rightly pointed out that this feature was too early for MWG. Agreed. github.com/GoogleChrome/modern-web-guidance-src/issues/1598