micro-interactions

name	micro-interactions
description	Rules for crafting high-fidelity, physics-based micro-interactions.

Micro-Interactions

When building interactive UI components, apply these rules to ensure "feel," continuity, and responsiveness.

Core Philosophy

• Immediate: Response must happen in <100ms.
• Continuous: Elements should morph and travel, not teleport.
• Playful: Use physics (springs) over time-based curves for interactive elements.
• Subtle: Micro-interactions should whisper, not shout.

1. Interaction & Feedback

• MUST provide immediate visual feedback on press (active state).
• SHOULD use scale for press states.
  • Button/Card standard: scale: 0.98 or 0.96.
  • Icon Button standard: scale: 0.9.
• SHOULD use whileTap in Motion or active:scale-* in Tailwind.
• NEVER block the UI thread during an interaction; trigger the animation and the action optimistically.
• MUST styling focus states for keyboard users (use focus-visible).

2. Motion Physics (Framer Motion)

• SHOULD prefer spring over tween for physical interactions (drag, scale, layout).
• Recommended Spring Configs:
  • Snappy (Buttons/Toggles): { stiffness: 400, damping: 25 }
  • Fluid (Modals/Drawers): { stiffness: 300, damping: 30 }
  • Bouncy (Notifications): { type: "spring", stiffness: 500, damping: 30, mass: 1 }
• NEVER use "lazy" springs (default stiffness < 100) for UI controls; it feels sluggish.

3. Spatial Continuity

• MUST use the layout prop in motion/react when an element changes position or size in the document flow.
• MUST use layoutId when an element logically moves between two different sub-trees (e.g., a list item expanding into a detail view).
• SHOULD use layout="position" if only the position changes, to avoid distorted scale transforms on children.
• MUST wrap removing items in <AnimatePresence mode="popLayout"> to prevent layout jumps.

4. Entrances & Exits

• MUST ensure exits are faster than entrances.
  • Entrance: duration: 0.3s to 0.5s (allow eye to track).
  • Exit: duration: 0.15s to 0.2s (get out of the way).
• SHOULD use staggerChildren for lists (> 3 items).
  • Stagger delay: 0.05s - 0.1s (keep it tight).
• SHOULD combine opacity + y (or scale) for standard entrances. Avoid x axis unless lateral movement is implied.

5. Tailwind & CSS Transitions

• USE for simple state changes (colors, subtle shadows, opacity).
• Standard Transition: transition-all duration-200 ease-out.
• Hover: hover:bg-opacity-80 or hover:brightness-110 > changing HSL values manually.
• NEVER transition height or width with CSS (causes reflow); use Framer Motion layout or ResizeObserver techniques if needed.

6. Accessibility

• MUST respect prefers-reduced-motion.
• Implementation:

  const shouldReduce = useReducedMotion();
  const transition = shouldReduce ? { duration: 0 } : { type: "spring" };
  

Reference Patterns

The "Rubber Band" Button

<motion.button
  whileHover={{ scale: 1.02 }}
  whileTap={{ scale: 0.95 }}
  transition={{ type: "spring", stiffness: 400, damping: 17 }}
>

The "Shared Layout" Tab (The Magic Pill)

{isSelected && (
  <motion.div
    layoutId="active-pill"
    className="absolute inset-0 bg-black rounded-full"
    transition={{ type: "spring", bounce: 0.2, duration: 0.6 }}
  />
)}