Matías Duarte - Motion Design

Animation is not decoration. Motion communicates relationships, hierarchy, and state changes.

Core Philosophy

Motion is Meaning

Every animation must answer: "What does this motion communicate?"

If the answer is "it looks cool" - remove it.

Physical Metaphors

Digital objects should feel like they have mass and respond to physics:

• Heavy objects move slower
• Light objects move faster
• Objects accelerate and decelerate (no linear motion)
• Objects don't teleport - they travel through space

Choreography

Multiple moving elements must be coordinated:

• Staggered, not simultaneous
• Parent leads, children follow
• Same direction = same intent

Motion Principles

1. Responsive

Acknowledge user input instantly.

/* Button feedback - immediate */
.button:active {
  transform: scale(0.98);
  transition: transform 0.05s ease-out;
}

2. Natural

Use easing that mimics physical objects.

/* Standard easing curves */
--ease-out: cubic-bezier(0.0, 0.0, 0.2, 1);     /* Decelerate - entering */
--ease-in: cubic-bezier(0.4, 0.0, 1, 1);        /* Accelerate - exiting */
--ease-in-out: cubic-bezier(0.4, 0.0, 0.2, 1);  /* Both - on-screen moves */

/* NEVER use linear for UI motion */

3. Aware

Elements know about each other.

/* Card expand: other cards move away */
.card.expanded ~ .card {
  transform: translateY(100px);
  transition: transform 0.3s var(--ease-out);
}

4. Intentional

Motion creates hierarchy and focus.

/* Important elements arrive first, leave last */
.modal {
  animation: modal-enter 0.3s var(--ease-out);
}

@keyframes modal-enter {
  from {
    opacity: 0;
    transform: scale(0.95) translateY(10px);
  }
}

Prescriptive Rules

Duration Scale

/* Based on travel distance and importance */
--duration-instant: 50ms;    /* Micro-interactions (button press) */
--duration-fast: 150ms;      /* Small movements (hover states) */
--duration-normal: 300ms;    /* Standard transitions (cards, modals) */
--duration-slow: 500ms;      /* Large movements (page transitions) */

/* Rule: Nothing over 500ms except loading/progress indicators */
/* Rule: Faster is almost always better */

Easing Usage

Transform Order

/* Combine transforms in this order for natural motion */
.element {
  transform: translate() scale() rotate();
}

/* Scale from center (default) or transform-origin for cards */
.card {
  transform-origin: center center;
}

Stagger Pattern

// List items enter staggered
items.forEach((item, i) => {
  item.style.animationDelay = `${i * 50}ms`;
});

// Rule: 50ms delay between items (max 500ms total)
// After 10 items, enter remaining simultaneously

Enter/Exit Asymmetry

/* Enter: slower, more elaborate */
.modal-enter {
  animation: fade-in 0.3s ease-out,
             slide-up 0.3s ease-out;
}

/* Exit: faster, simpler */
.modal-exit {
  animation: fade-out 0.2s ease-in;
}

/* Rule: Exit is always faster than enter */
/* Rule: Exit uses fewer properties than enter */

Common Patterns

Fade

.fade-enter {
  opacity: 0;
  animation: fade-in 0.2s ease-out forwards;
}

@keyframes fade-in {
  to { opacity: 1; }
}

Slide

.slide-enter {
  transform: translateY(20px);
  opacity: 0;
  animation: slide-in 0.3s ease-out forwards;
}

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

Scale

.scale-enter {
  transform: scale(0.95);
  opacity: 0;
  animation: scale-in 0.2s ease-out forwards;
}

@keyframes scale-in {
  to {
    transform: scale(1);
    opacity: 1;
  }
}

Expand/Collapse

.expandable {
  overflow: hidden;
  transition: max-height 0.3s ease-out;
}

.expandable.closed {
  max-height: 0;
}

.expandable.open {
  max-height: 500px; /* Must be greater than content */
}

When NOT to Animate

• User has prefers-reduced-motion enabled
• Repeated actions (don't animate every keystroke)
• Background/utility actions (auto-save)
• When animation would delay task completion

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

Review Checklist

• No animation over 500ms
• No linear easing on UI elements
• Enter animations longer than exit
• Stagger delay is 50ms, max 500ms total
• prefers-reduced-motion is respected
• Every animation has a communicative purpose
• Related elements animate together

Anti-Patterns

Duarte Score

Integration

Combine with:

• /visual - Material properties that motion must respect
• /usability - Feedback timing requirements
• /interaction - Input response expectations