transitions-dev

A library of 21 dependency-free CSS transitions for common web-interface changes. Each transition includes the HTML hooks, CSS variables, and a setting that respects users who prefer reduced motion.

In plain words
What is it for?
Use it for dropdowns, modals, panels, page transitions, tabs, badges, loading effects, changing numbers or text, and other interface state changes.
Why use it?
It provides ready-to-use motion patterns without requiring a framework or demo-specific code.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/vvedantb/eva/transitions-dev
Any agent
npx skills add vvedantb/eva --skill transitions-dev
Clone the repo
git clone --depth 1 https://github.com/vvedantb/eva

Made for: Claude Code, Codex.

Per session 280 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 5,674 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00280 $0.05674
Opus 5 $0.00140 $0.02837
Sonnet 5 $0.00056 $0.01135
Haiku 4.5 $0.00028 $0.00567

Measured 3d ago against content hash 0979309a0df5, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

transitions-dev scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 3d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

.agents/skills/transitions-dev/SKILL.md · 226 lines

How it starts

The opening of the file, as written. The whole thing — 226 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Transitions.dev

Twenty-one portable CSS transitions, each namespaced under t-* selectors with semantic CSS custom properties. Drop-in: paste the snippet, wire the documented HTML hooks, done. No framework dependencies, no demo-specific markup, and every snippet ships a prefers-reduced-motion guard.

Quick reference

Transition When to use Reference
Card resize Tween a container's width or height when its layout state changes. 01-card-resize.md
Number pop-in Re-enter each digit with a blurred slide when a number updates. 02-number-pop-in.md
Notification badge Slide a small badge onto a trigger and pop the dot. 03-notification-badge.md
Text states swap Swap text in place with a blurred up-and-down transition. 04-text-states-swap.md
Menu dropdown Open an origin-aware dropdown that grows from its trigger. 05-menu-dropdown.md
Modal open / close Scale-up modal dialog with a softer scale-down on close. 06-modal.md
Panel reveal Slide a panel into a region with a cross-blur. 07-panel-reveal.md
Page side-by-side Slide between two side-by-side pages (list ↔ detail, step 1 ↔ step 2). 08-page-side-by-side.md
Icon swap Cross-fade two icons in the same slot with blur and scale. 09-icon-swap.md
Success check Compose fade + rotate + Y-bob + path stroke-draw to celebrate a completed action. 10-success-check.md
Avatar group hover Distance-falloff lift on a row of items with a bouncy spring on return. 11-avatar-group-hover.md
Error state shake Per-segment cubic-bezier shake with auto-reverting border + message. 12-error-state-shake.md
Input clear with dissolve Fly-out + per-word streak when a text field is cleared. 13-input-clear-dissolve.md
Skeleton loader and reveal Pulse a placeholder, then cross-fade + cross-blur to the loaded content. 14-skeleton-reveal.md
Shimmer text Sweep a highlight band across muted text on a loop (pure CSS). 15-shimmer-text.md
Tabs sliding Slide the active pill between tabs in a segmented control. 16-tabs-sliding.md
Tooltip open/close Delayed fade+scale in, instant out (pure CSS). 17-tooltip.md
Texts reveal Staggered blurred rise for stacked text lines, quiet fade out. 18-texts-reveal.md
Card hover tilt Tilt a card in 3D toward the pointer with a cursor-tracked glare. 19-card-tilt.md
Plus to menu morph Morph a circular trigger into the menu / panel it opens. 20-plus-menu-morph.md
Accordion expand Grow / shrink a panel via grid-rows with a chevron flip. 21-accordion.md

Read the full file on GitHub · 226 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 3d ago First seen · 226 lines · 280 tokens per session scan A 0979309a0df5

Subscribe to this mod's changes

transitions-dev is a skill published in the GitHub repository vvedantb/eva (101 stars, last pushed 3d ago), licensed MIT. It adds 280 tokens to every session and 5,674 once invoked, about $0.0014 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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