Transitions.dev is an interactive collection of reusable CSS transitions. Each card on the index page demonstrates a different interaction pattern and ships a copy-ready, portable CSS snippet for each.

Live site: https://transitions.dev/

Each card has a copy button that emits a self-contained CSS snippet: semantic CSS custom properties on :root, the transition rules namespaced under t-* classes, and a @media (prefers-reduced-motion: reduce) guard — so you can paste the snippet into any project and apply it to any component without pulling in demo-specific markup or sizing.

Pull any transition into your project from the terminal — no manual copy:

npx transitions-pro add card-resize      # free — no account needed
npx transitions-pro list                 # see everything available

Pro transitions unlock after a passwordless browser sign-in (device flow — no API key in your terminal):

npx transitions-pro login                # opens the browser to confirm a code
npx transitions-pro add confetti-burst    # pulls the Pro CSS + React

CLI source: cli/ (published as the public transitions-pro package — it holds no premium source; Pro recipes are fetched from the authenticated API).

The same transitions are packaged as an installable agent skill so AI coding tools (Cursor, Claude Code, Codex, …) can apply them directly inside your project.

npx skills add Jakubantalik/transitions.dev

Skill source lives in skills/transitions-dev/ — SKILL.md, eighteen per-transition reference files (01-card-resize.md … 18-texts-reveal.md), and _root.css (the universal install block on its own).

The skill is generated from index.html so the snippets always match what the showcase site demonstrates. Re-run after editing the source site:

npm run build

build/extract.mjs parses PROTO_TEMPLATES and the :root { --pX-* } block out of index.html, then re-renders every file under skills/transitions-dev/ from the templates in build/templates/.

Refine is a live, agent-driven companion to the skill. One command drops a timeline + Refine panel onto your running app — no npm install, no source edits of your own — and every "Refine" click asks your coding agent to align the selected CSS/Motion transition to the transitions.dev motion tokens (or replace it with a transition from the library). Suggestions appear in a panel that slides in from the right; you pick which to apply as live, reversible overrides.

# inject the panel + start the local relay (deterministic suggestions work immediately)
npx transitions-refine live

# same, but also installs/wires the Cursor CLI so the relay answers with the LLM, persistently
npx transitions-refine live --llm

# remove the injected <script> tag again
npx transitions-refine stop

Without --llm, you can instead run /refine live in your editor to back the panel with the in-IDE agent. Source lives in refine/ and ships as the public npm package transitions-refine. See refine/README.md for the full flow and env knobs.

• index.html — main showcase page with all eighteen transitions and per-card "copy CSS" buttons.
• prototypes.html — interactive playground for each transition with live tuning controls (durations, distances, easings).
• skill.html — landing page for the agent skill (install instructions + side-by-side compare embed).
• example.html — modal demo with a side-by-side "generic AI output" vs "with Transitions.dev skill" toggle, embedded inside skill.html as an iframe.
• skills/transitions-dev/ — published skill payload (consumed by npx skills add).
• refine/ — the Refine tool: a CLI that injects a live timeline + Refine panel and runs a local relay (published to npm as transitions-refine).
• build/extract.mjs + build/templates/ — regenerator that keeps the skill in lockstep with index.html.
• assets/ — icons, favicons, and the social-share OG image.
• site.webmanifest, robots.txt, sitemap.xml — PWA/SEO metadata.

python3 -m http.server 8765

Then open http://127.0.0.1:8765/.