baseline-ui

baseline-ui is a skill for Claude Code, Codex from marchatton/agent-skills. It costs 19 tokens per session (800 once invoked), scanned A, a copy of baseline-ui, MIT.

A set of rules for designing and reviewing user interfaces. It covers styling choices, accessible controls, keyboard and focus behavior, animation, and reusable UI components.

In plain words
What is it for?
Use it when creating or reviewing interfaces, especially React and Tailwind CSS projects with buttons, menus, dialogs, animations, or other interactive elements.
Why use it?
It helps identify common usability and accessibility problems and gives concrete code-level fixes for them.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: installed under .agents/ (shared by several agents).

Good fit Use it when creating or reviewing interfaces, especially React and Tailwind CSS projects with buttons, menus, dialogs, animations, or other interactive elements.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/marchatton/agent-skills/baseline-ui
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add marchatton/agent-skills --skill baseline-ui
Clone the repo
git clone --depth 1 https://github.com/marchatton/agent-skills

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for baseline-ui

README.md
[![agentmods](https://agentmods.dev/badge/skills/marchatton/agent-skills/baseline-ui.svg)](https://agentmods.dev/skills/marchatton/agent-skills/baseline-ui)
Your own site
<a href="https://agentmods.dev/skills/marchatton/agent-skills/baseline-ui"><img src="https://agentmods.dev/badge/skills/marchatton/agent-skills/baseline-ui.svg" alt="Measured on agentmods" height="20"></a>
Per session 19 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 800 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin 92% copy Near-identical to another mod in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00019 $0.00800
Opus 5 $0.00010 $0.00400
Sonnet 5 $0.00004 $0.00160
Haiku 4.5 $0.00002 $0.00080

Measured 7d ago against content hash 615ac65dd37d, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade A, and why

baseline-ui scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 7d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

Origin

This is a copy

92% identical to baseline-ui — 15 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

.agents/skills/04-develop/01-ui-skills-dot-com/baseline-ui/SKILL.md · 89 lines

How it starts

The opening of the file, as written. The whole thing — 89 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Baseline UI

Source: ui-skills.com.

Enforces an opinionated UI baseline to prevent AI-generated interface slop.

How to use

  • Use baseline-ui to apply these constraints to any UI work in this conversation.
  • For file review, provide a file path 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 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
  • SHOULD respect prefers-reduced-motion
  • NEVER introduce custom easing curves unless explicitly requested
  • SHOULD avoid animating large images or full-screen surfaces

Read the full file on GitHub · 89 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 7d ago First seen · 89 lines · 19 tokens per session scan A 615ac65dd37d

Subscribe to this mod's changes

baseline-ui is a skill published in the GitHub repository marchatton/agent-skills (5 stars, last pushed 6mo ago), licensed MIT. It adds 19 tokens to every session and 800 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. It is 92% identical to baseline-ui, differing in 15 lines, and is treated as a copy.

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