Web Animation DesignSAFE

An open source template for building cloud agents.

The instruction file, verbatim from the audited commit — this is the text the model reads, and the surface the audit's instruction layer examines. Quoted here so you can judge it without cloning anything.

---
name: web-animation-design
description: "Design and implement web animations that feel natural and purposeful. Use this skill proactively whenever the user asks questions about animations, motion, easing, timing, duration, springs, transitions, or animation performance. This includes questions about how to animate specific UI elements, which easing to use, animation best practices, or accessibility considerations for motion. Triggers on: easing, ease-out, ease-in, ease-in-out, cubic-bezier, bounce, spring physics, keyframes, transform, opacity, fade, slide, scale, hover effects, microinteractions, Framer Motion, React Spring, GSAP, CSS transitions, entrance/exit animations, page transitions, stagger, will-change, GPU acceleration, prefers-reduced-motion, modal/dropdown/tooltip/popover/drawer animations, gesture animations, drag interactions, button press feel, feels janky, make it smooth."
metadata:
  short-description: Design and implement web animations that feel natural and purposeful
---

# Web Animation Design

A comprehensive guide for creating animations that feel right, based on Emil Kowalski's "Animations on the Web" course.

## Initial Response

When this skill is first invoked without a specific question, respond only with:

> I'm ready to help you with animations based on Emil Kowalski's animations.dev course.

Do not provide any other information until the user asks a question.

## Review Format (Required)

When reviewing animations, you MUST use a markdown table. Do NOT use a list with "Before:" and "After:" on separate lines. Always output an actual markdown table like this:

| Before                            | After                                           |
| --------------------------------- | ----------------------------------------------- |
| `transform: scale(0)`             | `transform: scale(0.95)`                        |
| `animation: fadeIn 400ms ease-in` | `animation: fadeIn 200ms ease-out`              |
| No reduced motion support         | `@media (prefers-reduced-motion: reduce) {...}` |

Wrong format (never do this):

```
Before: transform: scale(0)
After: transform: scale(0.95)
────────────────────────────
Before: 400ms duration
After: 200ms
```

Correct format: A single markdown table with | Before | After | columns, one row per issue.

## Quick Start

Every animation decision starts with these questions:

1. **Is this element entering or exiting?** → Use `ease-out`
2. **Is an on-screen element moving?** → Use `ease-in-out`
3. **Is this a hover/color transition?** → Use `ease`
4. **Will users see this 100+ times daily?** → Don't animate it

## The Easing Blueprint

### ease-out (Most Common)

Use for **user-initiated interactions**: dropdowns, modals, tooltips, any element entering or exiting the screen.

```css
/* Sorted weak to strong */
--ease-out-quad: cubic-bezier(0.25, 0.46, 0.45, 0.94);
--ease-out-cubic: cubic-bezier(0.215, 0.61, 0.355, 1);
--ease-out-quart: cubic-bezier(0.165, 0.84, 0.44, 1);
--ease-out-quint: cubic-bezier(0.23, 1, 0.32, 1);
--ease-out-expo: cubic-bezier(0.19, 1, 0.22, 1);
--ease-out-circ: cubic-bezier(0.075, 0.82, 0.165, 1);
```

Why it works: Acceleration at the start creates an instant, responsive feeling. The element "jumps" toward its destination then settles in.

### ease-in-out (For Movement)

Use when **elements already on screen need to move or morph**. Mimics natural motion like a car accelerating then braking.

```css
/* Sorted weak to strong */
--ease-in-out-quad: cubic-bezier(0.455, 0.03, 0.515, 0.955);
--ease-in-out-cubic: cubic-bezier(0.645, 0.045, 0.355, 1);
--ease-in-out-quart: cubic-bezier(0.77, 0, 0.175, 1);
--ease-in-out-quint: cubic-bezier(0.86, 0, 0.07, 1);
--ease-in-out-expo: cubic-bezier(1, 0, 0, 1);
--ease-in-out-circ: cubic-bezier(0.785, 0.135, 0.15, 0.86);
```

### ease (For Hover Effects)

Use for **hover states and color transitions**. The asymmetrical curve (faster start, slower end) feels elegant for gentle animations.

```css
transition: background-color 150ms ease;
```

### linear (Avoid in UI)

Only use for:

- Constant-speed animations (marquees, tickers)
- Time visualization (hold-to-delete progress indicators)

Linear feels robotic and unnatural for interactive elements.

### ease-in (Almost Never)

**Avoid for UI animations.** Makes interfaces feel sluggish because the slow start delays visual feedback.

### Paired Elements Rule

Elements that animate together must use the same easing and duration. Modal + overlay, tooltip + arrow, drawer + backdrop—if they move as a unit, they should feel like a unit.

```css
/* Both use the same timing */
.modal {
  transition: transform 200ms ease-out;
}
.overlay {
  transition: opacity 200ms ease-out;
}
```

## Timing and Duration

## Duration Guidelines

| Element Type                      | Duration  |
| --------------------------------- | --------- |
| Micro-interactions                | 100-150ms |
| Standard UI (tooltips, dropdowns) | 150-250ms |
| Modals, drawers                   | 200-300ms |

**Rules:**
- UI animations should stay under 300ms
- Larger elements animate slower than smaller ones
- Exit animations can be ~20% faster than entrance
- Match duration to distance - longer travel = longer duration

### The Frequency

Determine how often users will see the animation:

- **100+ times/day** → No animation (or drastically reduced)
- **Occasional use** → Standard animation
- **Rare/first-time** → Can be more special

**Example:** Raycast never animates because users open it hundreds of times a day.

## When to Animate

**Do animate:**

- Enter/exit transitions for spatial consistency
- State changes that benefit from visual continuity
- Responses to user actions (feedback)
- Rarely-used interactions where delight adds value

**Don't animate:**

- Keyboard-initiated actions
- Hover effects on frequently-used elements
- Anything users interact with 100+ times daily
- When speed matters more than smoothness

**Marketing vs. Product:**

- M

SAFEgrade B · trust 89/100 Nothing in the source contradicts what it says it does. Grade A is reserved for packages that have also passed the behavioural sandbox.

What the source does

Filesystem

none-observed

Network

none-observed

Shell

none-observed

Dependencies

pinned

Secrets in source

none-found

Findings (1)

CLAUDE.md

Gates applied: no_behavioural_pass.

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