Agent skill

motion-scale

Generates animation duration, easing curves, and delay tokens with prefers-reduced-motion support. Use when creating transition timing, animation speed, or motion systems. Outputs CSS, Tailwind, or JSON.

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Install this agent skill to your Project

npx add-skill https://github.com/majiayu000/claude-skill-registry/tree/main/skills/data/motion-scale

SKILL.md

Motion Scale Generator

Overview

Generate consistent animation and transition tokens for duration, easing, and delay. Creates a motion system that feels cohesive and respects user preferences for reduced motion.

When to Use

  • Setting up animation tokens for a new project
  • Standardizing transition timing across components
  • Replacing hardcoded animation values
  • Implementing reduced motion support
  • Building micro-interaction patterns

Quick Reference: Duration Scale

Token Value Use Case
instant 0ms Immediate, no animation
fastest 50ms Micro-feedback (ripples, highlights)
fast 100ms Hover, focus, small changes
normal 200ms Most transitions, toggles
slow 300ms Modals, drawers, reveals
slower 400ms Page transitions, complex sequences
slowest 500ms Elaborate animations, onboarding

Quick Reference: Easing Curves

Token Curve Use Case
linear linear Progress bars, looping
ease-in cubic-bezier(0.4, 0, 1, 1) Exit animations
ease-out cubic-bezier(0, 0, 0.2, 1) Enter animations (most common)
ease-in-out cubic-bezier(0.4, 0, 0.2, 1) Move, resize, continuous
ease-bounce cubic-bezier(0.34, 1.56, 0.64, 1) Playful, attention
ease-elastic cubic-bezier(0.68, -0.55, 0.27, 1.55) Springy, overshoot

The Process

  1. Choose duration scale: How many steps? (5-7 typical)
  2. Define base duration: 200ms is standard baseline
  3. Select ratio: How durations scale (1.5x or 2x)
  4. Pick easing curves: Standard set + any special curves
  5. Create semantic aliases: Map to component behaviors
  6. Add reduced motion: Respect user preferences
  7. Choose format: CSS, Tailwind, or JSON

Output Formats

CSS Custom Properties:

css
:root {
  /* ===== Durations ===== */
  --duration-0: 0ms;
  --duration-50: 50ms;
  --duration-100: 100ms;
  --duration-150: 150ms;
  --duration-200: 200ms;
  --duration-300: 300ms;
  --duration-400: 400ms;
  --duration-500: 500ms;
  --duration-700: 700ms;
  --duration-1000: 1000ms;

  /* Named aliases */
  --duration-instant: var(--duration-0);
  --duration-fastest: var(--duration-50);
  --duration-fast: var(--duration-100);
  --duration-normal: var(--duration-200);
  --duration-slow: var(--duration-300);
  --duration-slower: var(--duration-500);
  --duration-slowest: var(--duration-700);

  /* ===== Easings ===== */
  --ease-linear: linear;
  --ease-in: cubic-bezier(0.4, 0, 1, 1);
  --ease-out: cubic-bezier(0, 0, 0.2, 1);
  --ease-in-out: cubic-bezier(0.4, 0, 0.2, 1);

  /* Expressive easings */
  --ease-bounce: cubic-bezier(0.34, 1.56, 0.64, 1);
  --ease-elastic: cubic-bezier(0.68, -0.55, 0.27, 1.55);
  --ease-snap: cubic-bezier(0.2, 0, 0, 1);

  /* Deceleration/Acceleration (Material Design style) */
  --ease-decelerate: cubic-bezier(0, 0, 0.2, 1);
  --ease-accelerate: cubic-bezier(0.4, 0, 1, 1);
  --ease-standard: cubic-bezier(0.4, 0, 0.2, 1);

  /* ===== Delays ===== */
  --delay-none: 0ms;
  --delay-short: 50ms;
  --delay-medium: 100ms;
  --delay-long: 200ms;

  /* Stagger delays for sequential animations */
  --delay-stagger-1: 0ms;
  --delay-stagger-2: 50ms;
  --delay-stagger-3: 100ms;
  --delay-stagger-4: 150ms;
  --delay-stagger-5: 200ms;

  /* ===== Semantic Transitions ===== */
  --transition-colors: color, background-color, border-color, fill, stroke;
  --transition-opacity: opacity;
  --transition-transform: transform;
  --transition-shadow: box-shadow;
  --transition-all: all;

  /* Component transitions */
  --transition-hover: var(--duration-fast) var(--ease-out);
  --transition-focus: var(--duration-fast) var(--ease-out);
  --transition-active: var(--duration-fastest) var(--ease-out);
  --transition-enter: var(--duration-normal) var(--ease-out);
  --transition-exit: var(--duration-fast) var(--ease-in);
  --transition-move: var(--duration-normal) var(--ease-in-out);
  --transition-expand: var(--duration-slow) var(--ease-out);
  --transition-collapse: var(--duration-normal) var(--ease-in);
}

/* ===== Reduced Motion ===== */
@media (prefers-reduced-motion: reduce) {
  :root {
    --duration-50: 0ms;
    --duration-100: 0ms;
    --duration-150: 0ms;
    --duration-200: 0ms;
    --duration-300: 0ms;
    --duration-400: 0ms;
    --duration-500: 0ms;
    --duration-700: 0ms;
    --duration-1000: 0ms;
  }
}

/* Alternative: Keep minimal motion */
@media (prefers-reduced-motion: reduce) {
  :root {
    --duration-fastest: 0ms;
    --duration-fast: 0ms;
    --duration-normal: 50ms;  /* Minimal feedback */
    --duration-slow: 50ms;
    --duration-slower: 100ms;
    --duration-slowest: 100ms;

    /* Disable expressive easings */
    --ease-bounce: var(--ease-out);
    --ease-elastic: var(--ease-out);
  }
}

Tailwind Config:

js
module.exports = {
  theme: {
    extend: {
      transitionDuration: {
        '0': '0ms',
        '50': '50ms',
        '100': '100ms',
        '150': '150ms',
        '200': '200ms',
        '300': '300ms',
        '400': '400ms',
        '500': '500ms',
        '700': '700ms',
        '1000': '1000ms',
      },
      transitionTimingFunction: {
        'in': 'cubic-bezier(0.4, 0, 1, 1)',
        'out': 'cubic-bezier(0, 0, 0.2, 1)',
        'in-out': 'cubic-bezier(0.4, 0, 0.2, 1)',
        'bounce': 'cubic-bezier(0.34, 1.56, 0.64, 1)',
        'elastic': 'cubic-bezier(0.68, -0.55, 0.27, 1.55)',
        'snap': 'cubic-bezier(0.2, 0, 0, 1)',
      },
      transitionDelay: {
        '0': '0ms',
        '50': '50ms',
        '100': '100ms',
        '150': '150ms',
        '200': '200ms',
      },
      animation: {
        'fade-in': 'fade-in 200ms ease-out',
        'fade-out': 'fade-out 150ms ease-in',
        'slide-up': 'slide-up 200ms ease-out',
        'slide-down': 'slide-down 200ms ease-out',
        'scale-in': 'scale-in 200ms ease-out',
        'spin-slow': 'spin 2s linear infinite',
      },
      keyframes: {
        'fade-in': {
          '0%': { opacity: '0' },
          '100%': { opacity: '1' },
        },
        'fade-out': {
          '0%': { opacity: '1' },
          '100%': { opacity: '0' },
        },
        'slide-up': {
          '0%': { transform: 'translateY(10px)', opacity: '0' },
          '100%': { transform: 'translateY(0)', opacity: '1' },
        },
        'slide-down': {
          '0%': { transform: 'translateY(-10px)', opacity: '0' },
          '100%': { transform: 'translateY(0)', opacity: '1' },
        },
        'scale-in': {
          '0%': { transform: 'scale(0.95)', opacity: '0' },
          '100%': { transform: 'scale(1)', opacity: '1' },
        },
      },
    },
  },
};

JSON Tokens:

json
{
  "motion": {
    "duration": {
      "0": { "value": "0ms", "type": "duration" },
      "50": { "value": "50ms", "type": "duration" },
      "100": { "value": "100ms", "type": "duration" },
      "200": { "value": "200ms", "type": "duration" },
      "300": { "value": "300ms", "type": "duration" },
      "500": { "value": "500ms", "type": "duration" }
    },
    "easing": {
      "linear": { "value": "linear", "type": "cubicBezier" },
      "ease-in": { "value": "cubic-bezier(0.4, 0, 1, 1)", "type": "cubicBezier" },
      "ease-out": { "value": "cubic-bezier(0, 0, 0.2, 1)", "type": "cubicBezier" },
      "ease-in-out": { "value": "cubic-bezier(0.4, 0, 0.2, 1)", "type": "cubicBezier" },
      "bounce": { "value": "cubic-bezier(0.34, 1.56, 0.64, 1)", "type": "cubicBezier" }
    },
    "delay": {
      "none": { "value": "0ms", "type": "duration" },
      "short": { "value": "50ms", "type": "duration" },
      "medium": { "value": "100ms", "type": "duration" }
    }
  }
}

Easing Curve Reference

Standard Curves

ease-out (enter/appear):
    ●━━━━━━━━━━━━━━━━━━●
    Fast start, gentle stop
    Best for: Elements entering view

ease-in (exit/leave):
    ●━━━━━━━━━━━━━━━━━━●
    Gentle start, fast end
    Best for: Elements leaving view

ease-in-out (move/resize):
    ●━━━━━━━━━━━━━━━━━━●
    Gentle start and end
    Best for: Elements moving position

linear (progress):
    ●━━━━━━━━━━━━━━━━━━●
    Constant speed
    Best for: Progress bars, spinners

Expressive Curves

bounce (playful):
    ●━━━━━━━━╮
            ╰━━━●
    Overshoots then settles
    Best for: Notifications, confirmations

elastic (springy):
    ●━━━╮   ╭━╮
        ╰━━━╯ ╰●
    Oscillates before settling
    Best for: Attention, drag-and-drop

snap (decisive):
    ●━━━━━━━━━━━━━━━━●
    Very fast deceleration
    Best for: Snapping, selections

Custom Curve Creation

css
/*
  cubic-bezier(x1, y1, x2, y2)

  x1, y1 = First control point (affects start)
  x2, y2 = Second control point (affects end)

  y values > 1 = overshoot
  y values < 0 = anticipation
*/

/* Dramatic entrance */
--ease-dramatic: cubic-bezier(0.2, 0.8, 0.2, 1);

/* Snappy with slight overshoot */
--ease-snappy: cubic-bezier(0.2, 1.2, 0.3, 1);

/* Gentle float */
--ease-float: cubic-bezier(0.4, 0.2, 0.2, 1);

Component Patterns

Button Hover

css
.button {
  transition:
    background-color var(--transition-hover),
    transform var(--transition-active);
}

.button:hover {
  background-color: var(--color-primary-600);
}

.button:active {
  transform: scale(0.98);
}

Modal Enter/Exit

css
.modal-backdrop {
  transition: opacity var(--duration-normal) var(--ease-out);
}

.modal-content {
  transition:
    opacity var(--duration-normal) var(--ease-out),
    transform var(--duration-normal) var(--ease-out);
}

/* Enter */
.modal-backdrop.entering { opacity: 0; }
.modal-backdrop.entered { opacity: 1; }
.modal-content.entering { opacity: 0; transform: scale(0.95) translateY(10px); }
.modal-content.entered { opacity: 1; transform: scale(1) translateY(0); }

/* Exit (faster) */
.modal-backdrop.exiting {
  opacity: 0;
  transition-duration: var(--duration-fast);
}
.modal-content.exiting {
  opacity: 0;
  transform: scale(0.95);
  transition-duration: var(--duration-fast);
}

Dropdown Menu

css
.dropdown-menu {
  transform-origin: top;
  transition:
    opacity var(--duration-fast) var(--ease-out),
    transform var(--duration-fast) var(--ease-out);
}

.dropdown-menu[data-state="closed"] {
  opacity: 0;
  transform: scaleY(0.9);
  pointer-events: none;
}

.dropdown-menu[data-state="open"] {
  opacity: 1;
  transform: scaleY(1);
}

Staggered List Animation

css
.list-item {
  opacity: 0;
  transform: translateY(10px);
  animation: slide-up var(--duration-normal) var(--ease-out) forwards;
}

.list-item:nth-child(1) { animation-delay: var(--delay-stagger-1); }
.list-item:nth-child(2) { animation-delay: var(--delay-stagger-2); }
.list-item:nth-child(3) { animation-delay: var(--delay-stagger-3); }
.list-item:nth-child(4) { animation-delay: var(--delay-stagger-4); }
.list-item:nth-child(5) { animation-delay: var(--delay-stagger-5); }

@keyframes slide-up {
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

Loading Spinner

css
.spinner {
  animation: spin var(--duration-1000) var(--ease-linear) infinite;
}

@keyframes spin {
  to { transform: rotate(360deg); }
}

/* Pulsing loader */
.pulse {
  animation: pulse var(--duration-700) var(--ease-in-out) infinite alternate;
}

@keyframes pulse {
  0% { opacity: 0.4; transform: scale(0.95); }
  100% { opacity: 1; transform: scale(1); }
}

Skeleton Loading

css
.skeleton {
  background: linear-gradient(
    90deg,
    var(--color-gray-200) 0%,
    var(--color-gray-100) 50%,
    var(--color-gray-200) 100%
  );
  background-size: 200% 100%;
  animation: shimmer 1.5s var(--ease-in-out) infinite;
}

@keyframes shimmer {
  0% { background-position: 200% 0; }
  100% { background-position: -200% 0; }
}

Reduced Motion

Strategy 1: Remove All Motion

css
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
}

Strategy 2: Reduce, Don't Remove

css
@media (prefers-reduced-motion: reduce) {
  :root {
    /* Keep brief transitions for feedback */
    --duration-fast: 0ms;
    --duration-normal: 50ms;
    --duration-slow: 100ms;

    /* Simplify easings */
    --ease-bounce: var(--ease-out);
    --ease-elastic: var(--ease-out);
  }

  /* Disable parallax, auto-play, infinite loops */
  .parallax { transform: none !important; }
  .auto-animate { animation: none !important; }
}

Strategy 3: Provide Alternatives

css
/* Full motion */
.card-enter {
  animation: slide-up var(--duration-normal) var(--ease-out);
}

/* Reduced: fade only, no movement */
@media (prefers-reduced-motion: reduce) {
  .card-enter {
    animation: fade-in var(--duration-fast) var(--ease-out);
  }
}

Duration Guidelines

Duration Feel Use For
0-50ms Instant Ripples, micro-feedback
50-100ms Snappy Hover states, focus, toggles
100-200ms Quick Most UI transitions
200-300ms Smooth Modals, panels, reveals
300-500ms Deliberate Page transitions, onboarding
500ms+ Slow Complex sequences, emphasis

Rule of thumb:

  • Smaller elements = faster (50-150ms)
  • Larger elements = slower (200-400ms)
  • User-triggered = fast (100-200ms)
  • System-triggered = can be slower (200-400ms)

Testing Checklist

  • Transitions feel smooth, not jarring
  • Hover/focus feedback is immediate (<150ms)
  • Modals/drawers don't feel sluggish
  • Animations enhance, don't block interaction
  • prefers-reduced-motion is respected
  • No layout shift during animations
  • Animations work at 60fps
  • Consistent timing across similar interactions

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