MUST use Tailwind CSS defaults unless custom values already exist or are explicitly requested
MUST use motion/react (formerly framer-motion) when JavaScript animation is required
SHOULD use tw-animate-css for entrance and micro-animations in Tailwind CSS
MUST use cn utility (clsx + tailwind-merge) for class logic

Components

MUST use accessible component primitives for anything with keyboard or focus behavior (Base UI, React Aria, Radix)
MUST use the project’s existing component primitives first
NEVER mix primitive systems within the same interaction surface
SHOULD prefer Base UI for new primitives if compatible with the stack
MUST add an aria-label to icon-only buttons
NEVER rebuild keyboard or focus behavior by hand unless explicitly requested

Interaction

NEVER add animation unless it is explicitly requested
MUST animate only compositor props (transform, opacity)
NEVER animate layout properties (width, height, top, left, margin, padding)
SHOULD avoid animating paint properties (background, color) except for small, local UI (text, icons)
SHOULD use ease-out on entrance
NEVER exceed 200ms for interaction feedback
MUST pause looping animations when off-screen
SHOULD respect prefers-reduced-motion
NEVER introduce custom easing curves unless explicitly requested
SHOULD avoid animating large images or full-screen surfaces

NEVER use gradients unless explicitly requested
NEVER use purple or multicolor gradients
NEVER use glow effects as primary affordances
SHOULD use Tailwind CSS default shadow scale unless explicitly requested
MUST give empty states one clear next action
SHOULD limit accent color usage to one per view
SHOULD use existing theme or Tailwind CSS color tokens before introducing new ones