baseline-ui – Design & UI skill for AI agents

Baseline UI

When to Use

Use this skill when you need quickly deslop UI code by fixing spacing, hierarchy, typography, and small layout issues. Use when the interface needs a fast cleanup or polish pass.

Applies an opinionated baseline for a scoped polish pass. Existing product design, accessibility requirements, framework choices and explicit user preferences take precedence; do not migrate the stack or add dependencies just to satisfy this list.

How to use

• /baseline-ui

Apply these constraints to any UI work in this conversation.

• /baseline-ui <file>

Review the file against all constraints below and output:

• violations (quote the exact line/snippet)
• why it matters (1 short sentence)
• a concrete fix (code-level suggestion)

Stack

• 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](https://base-ui.com/react/components) 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

• MUST use an AlertDialog for destructive or irreversible actions
• SHOULD use structural skeletons for loading states
• NEVER use h-screen, use h-dvh
• MUST respect safe-area-inset for fixed elements
• MUST show errors next to where the action happens
• NEVER block paste in input or textarea elements

Animation

• 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
• MUST respect prefers-reduced-motion
• NEVER introduce custom easing curves unless explicitly requested
• SHOULD avoid animating large images or full-screen surfaces

Typography

• MUST use text-balance for headings and text-pretty for body/paragraphs
• MUST use tabular-nums for data
• SHOULD use truncate or line-clamp for dense UI
• NEVER modify letter-spacing (tracking-*) unless explicitly requested

Layout

• MUST use a fixed z-index scale (no arbitrary z-*)
• SHOULD use size-* for square elements instead of w-* + h-*

Performance

• NEVER animate large blur() or backdrop-filter surfaces
• NEVER apply will-change outside an active animation
• NEVER use useEffect for anything that can be expressed as render logic

Design

• 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

Example

User request:

> Review this interface with @baseline-ui, identify the highest-impact design problems, and propose an implementation-ready improvement.

Limitations

• Use this skill only when the task clearly matches its upstream source and local project context.
• Verify commands, generated code, dependencies, credentials, and external service behavior before applying changes.
• Do not treat examples as a substitute for environment-specific tests, security review, or user approval for destructive or costly actions.