* Detect single-edge stripes painted with an inset box-shadow
The side-tab rule caught bordered stripes but not the inset box-shadow spelling of
the same anti-pattern, which is how it usually reaches an Astro/CSS source file.
Adds a structural CSS scan for `box-shadow: inset` layers whose shape is a 3-12px
stripe on exactly one edge with no blur or spread, reusing the existing `side-tab`
rule id, so the rule count is unchanged.
Scoped narrowly, because a stripe is correct design in some places. It skips
selection and focus indicators (the rule's one documented exception), interactive
and semantic elements, narrow artwork, and neutral colors: `inset 4px 0 0 #000` is
a hairline, not an AI tell. Chromatic intent is read from the color literal or from
a `var(--token)` name.
Grammar rather than one spelling, learned the hard way — three of the four
false-negative shapes below were found only after the first pass shipped:
- `inset` is order-independent, so `4px 0 0 red inset` is the same stripe. Only a
standalone keyword is stripped, so `var(--inset-accent)` is not mangled.
- box-shadow takes <length>{2,4}: `inset 4px 0 red` omits blur and spread, which
default to 0. That is exactly the stripe shape.
- Authored CSS spells neutrals as `#000` / `black`, and shared/color.mjs only
parses the computed function forms a browser emits, deliberately reporting
anything else as chromatic. Routing authored colors through it flagged plain
black hairlines, so hex and named neutrals are handled before deferring.
- Comment bodies are blanked before matching, preserving byte offsets so line
numbers stay right, and the selector's line is taken from its first
non-whitespace character rather than the greedy match start.
Fixture covers 8 flag shapes and 13 pass shapes, including a literal-color column
that the original had none of, which is why the neutral bug survived review.
Prepared with AI assistance under maintainer direction.
Co-Authored-By: Claude <noreply@anthropic.com>
* Parse box-shadow layers by grammar, not by one spelling
Three review-bot findings, two of them the same mistake I had already made
twice in this rule.
Color-first layers were missed (greptile). `box-shadow` orders `inset`,
the lengths, and the color freely, so `red 4px 0 inset` and
`var(--brand-accent) 4px 0 0 inset` paint the stripe the length-first
regex was looking for and were skipped. That is the third valid spelling
this rule has missed after trailing `inset` and the two-length form, all
from encoding one spelling instead of the grammar. Stop patching
spellings: tokenize the layer, pick out `inset` and the 2-4 lengths in any
order, and treat the single remaining token as the color. Tokenizing is
paren-aware because `rgb(0 0 0)` is one color value whose channels would
otherwise read as lengths.
Neutral `rgb()` with space-separated channels was flagged (cursor).
shared/color.mjs parses only the comma form that getComputedStyle emits,
so an authored `rgb(0 0 0)` fell through it and reported chromatic — the
exemption isNeutralAuthoredColor exists for, missed. Parse both separators
before delegating. Left shared/color.mjs alone: it reads computed styles,
where the comma form is all a browser produces.
Line numbers were derived by re-slicing the whole prefix per rule, O(n^2)
on a large stylesheet (Copilot). Matches arrive in source order, so carry
a monotonic cursor: one pass total.
Fixtures cover both flag shapes and the neutral pass shape; all three fail
against the previous parse ("expected Color First Edge to flag", and
Space Rgb Neutral Edge appearing in the old flag list).
Assisted-by: Claude Code
* Fix the !important regression my tokenizer introduced, plus two cascade bugs
Three findings from Cursor on the grammar rewrite. The first is mine, from
the commit that claimed to end this bug class.
`!important` stopped flagging. Tokenizing split it into its own token, so
the color count came out at two and the layer was skipped — a shape the
regex it replaced handled correctly. `!important` qualifies the
declaration, not the shadow value, so strip it before reading layers.
Style-block findings reported one line low. block.startLine is the first
line after the <style> tag, but block.content begins at the character right
after that tag, so content's own line 1 sits on the tag's line. Passing
startLine - 1 to a 1-based line lookup counted that line twice. It is
startLine - 2. runRegexMatchers is unaffected and stays at startLine - 1
because it indexes its split lines from zero — verified by a fixture where
bounce-easing and side-tab share one block and now both report correctly.
Repeated declarations read the first, not the last. The cascade paints the
last, so `box-shadow: inset 4px 0 red; box-shadow: none` was flagged
though it paints nothing, and the reverse order was missed. Same for a
width override deciding the narrow-artwork skip.
Fixtures cover !important, both cascade orders, and the line-accuracy
shapes (multi-line block, single-line block, plain .css); they fail against
the previous commit.
Assisted-by: Claude Code
---------
Co-authored-by: Claude <noreply@anthropic.com>
Impeccable
Design guidance for AI coding agents. 1 skill, 23 commands, live browser iteration, and 46 deterministic detector rules for AI-generated frontend design.
Quick start: From your project root, run
npx impeccable install, then run/impeccable initinside your AI coding tool. Full docs: impeccable.style.
Why Impeccable?
Anthropic's frontend-design was the first widely-used design skill for Claude. Impeccable started from there.
Every model trained on the same SaaS templates. Skip the guidance and you get the same handful of tells on every project: Inter for everything, purple-to-blue gradients, cards nested in cards, gray text on colored backgrounds, the rounded-square icon tile above every heading.
Impeccable adds:
- One setup flow.
/impeccable initwritesPRODUCT.mdand offersDESIGN.md, so later commands know the audience, brand/product lane, voice, anti-references, colors, type, and components. - 23 commands. A shared design vocabulary with your AI:
polish,audit,critique,distill,animate,bolder,quieter, and more. - 46 deterministic detector rules plus LLM-only critique checks. The CLI and browser extension run the deterministic rules with no LLM and no API key.
What's Included
The Skill: impeccable
The skill installs as one command:
/impeccable <command> <target>
Start every new project with:
/impeccable init
init asks whether the surface is brand (marketing, landing, portfolio) or product (app UI, dashboard, tool), then writes design context that every later command reads.
23 Commands
All commands are accessed through /impeccable:
| Command | What it does |
|---|---|
/impeccable craft |
Full shape-then-build flow with visual iteration |
/impeccable init |
One-time setup: gather design context, write PRODUCT.md and DESIGN.md, configure live mode, recommend next steps |
/impeccable document |
Generate root DESIGN.md from existing project code |
/impeccable extract |
Pull reusable components and tokens into the design system |
/impeccable shape |
Plan UX/UI before writing code |
/impeccable critique |
UX design review: hierarchy, clarity, emotional resonance |
/impeccable audit |
Run technical quality checks (a11y, performance, responsive) |
/impeccable polish |
Final pass, design system alignment, and shipping readiness |
/impeccable bolder |
Amplify boring designs |
/impeccable quieter |
Tone down overly bold designs |
/impeccable distill |
Strip to essence |
/impeccable harden |
Error handling, i18n, text overflow, edge cases |
/impeccable onboard |
First-run flows, empty states, activation paths |
/impeccable animate |
Add purposeful motion |
/impeccable colorize |
Introduce strategic color |
/impeccable typeset |
Fix font choices, hierarchy, sizing |
/impeccable layout |
Fix layout, spacing, visual rhythm |
/impeccable delight |
Add moments of joy |
/impeccable overdrive |
Add technically extraordinary effects |
/impeccable clarify |
Improve unclear UX copy |
/impeccable adapt |
Adapt for different devices |
/impeccable optimize |
Performance improvements |
/impeccable live |
Visual variant mode: iterate on elements in the browser |
Use /impeccable pin <command> to create standalone shortcuts (e.g., pin audit creates /audit).
Usage Examples
/impeccable audit blog # Audit blog hub + post pages
/impeccable critique landing # UX design review
/impeccable polish settings # Final pass before shipping
/impeccable harden checkout # Add error handling + edge cases
Or use /impeccable directly with a description:
/impeccable redo this hero section
Anti-Patterns
The skill includes explicit guidance on what to avoid:
- Don't use overused fonts (Arial, Inter, system defaults)
- Don't use gray text on colored backgrounds
- Don't use pure black/gray (always tint)
- Don't wrap everything in cards or nest cards inside cards
- Don't use bounce/elastic easing (feels dated)
See It In Action
Visit the Neo Mirai case study to see a before/after case study of a real project transformed with Impeccable commands.
Installation
Option 1: CLI installer (Recommended)
From the root of your project, run:
npx impeccable install
This shows the harness folders it detected (for example ~/.claude, ~/.codex, or project-local .cursor), lets you keep the detected set or customize providers, then asks whether to install into the current project or globally. Use --providers=claude,codex,cursor and --scope=project|global to skip those choices in scripts. On Claude Code, Cursor, and Codex, it also installs the provider-native hook manifest for the current project. Works with Cursor, Claude Code, Gemini CLI, Codex CLI, Grok Build, and every other supported tool. Reload your harness afterward.
To refresh an existing install, run:
npx impeccable update
Codex users should open /hooks after install or update and approve the project hook when prompted. Codex tracks trust by hook definition, so updates that change .codex/hooks.json can require approval again.
Option 2: Git Submodule
For teams that want to keep Impeccable vendored and updated through Git, add this repo as a submodule and link the compiled provider build into your harness folders:
git submodule add https://github.com/pbakaus/impeccable .impeccable
npx impeccable link --source=.impeccable --providers=claude,cursor
git add .gitmodules .impeccable .claude .cursor
git commit -m "Add Impeccable skills"
Use the providers your project needs, for example claude, cursor, gemini, codex, github, opencode, pi, qoder, trae, trae-cn, or rovo-dev. The command links individual skill folders from .impeccable/dist/universal/ and leaves existing real skill directories untouched unless you pass --force.
To update later:
git submodule update --remote .impeccable
npx impeccable link --source=.impeccable --providers=claude,cursor
Option 3: Plugin install
Claude Code:
/plugin marketplace add pbakaus/impeccable
Claude Code only. After adding the marketplace, open
/pluginand install Impeccable from the list.
Grok Build:
grok plugin install pbakaus/impeccable --trust
Grok Build only. Then run
/impeccable initin a Grok session.
Option 4: Download from Website
Visit impeccable.style, download the ZIP for your tool, and extract to your project.
Option 5: Copy from Repository
Cursor:
cp -r dist/cursor/.cursor your-project/
Note: Cursor skills require setup:
- Switch to Nightly channel in Cursor Settings → Beta
- Enable Agent Skills in Cursor Settings → Rules
Claude Code:
# Project-specific
cp -r dist/claude-code/.claude your-project/
# Or global (applies to all projects)
cp -r dist/claude-code/.claude/* ~/.claude/
OpenCode:
cp -r dist/opencode/.opencode your-project/
Pi:
cp -r dist/pi/.pi your-project/
Gemini CLI:
cp -r dist/gemini/.gemini your-project/
Note: Gemini CLI skills require setup:
- Install preview version:
npm i -g @google/gemini-cli@preview- Run
/settingsand enable "Skills"- Run
/skills listto verify installation
Codex CLI:
# Project-local
cp -r dist/agents/.agents your-project/
mkdir -p your-project/.codex
cp dist/codex/.codex/hooks.json your-project/.codex/hooks.json
# Or install the skill user-wide. Copy .codex/hooks.json into each project
# where you want the design hook to run.
mkdir -p ~/.agents/skills
cp -r dist/agents/.agents/skills/* ~/.agents/skills/
The asset-producer subagent ships nested inside the skill's own
agents/folder, which Codex auto-discovers. No separate.codex/agents/copy is needed. The hook is project-local because Codex discovers hooks from.codex/hooks.jsonnext to trusted project config.
GitHub Copilot:
cp -r dist/github/.github your-project/
Trae:
# Trae China (domestic version)
cp -r dist/trae/.trae-cn/skills/* ~/.trae-cn/skills/
# Trae International
cp -r dist/trae/.trae/skills/* ~/.trae/skills/
Note: Trae has two versions with different config directories:
- Trae China:
~/.trae-cn/skills/- Trae International:
~/.trae/skills/After copying, restart Trae IDE to activate the skills.
Rovo Dev:
# Project-specific
cp -r dist/rovo-dev/.rovodev your-project/
# Or global (applies to all projects)
cp -r dist/rovo-dev/.rovodev/skills/* ~/.rovodev/skills/
Qoder:
# Project-specific
cp -r dist/qoder/.qoder your-project/
# Or global (applies to all projects)
cp -r dist/qoder/.qoder/skills/* ~/.qoder/skills/
Usage
Once installed, every command runs through the single /impeccable skill:
/impeccable audit # Find issues
/impeccable polish # Final cleanup
/impeccable distill # Remove complexity
/impeccable critique # Full design review
Type /impeccable alone to see the full command list.
Most commands accept an optional argument to focus on a specific area:
/impeccable audit the header
/impeccable polish the checkout form
If you reach for one command often, pin it with /impeccable pin audit to get /audit as a standalone shortcut.
Note: Codex uses skills here, not /prompts: commands. Open /skills or type $impeccable. Repo-local installs live in .agents/skills/; user-wide installs live in ~/.agents/skills/. GitHub Copilot uses .github/skills/. Restart the tool if a newly installed skill does not appear.
Keeping .impeccable out of git
As you run commands, Impeccable writes working files under .impeccable/: critique and polish screenshots, live-mode session and preview state, runtime caches, and per-developer config. Most of it is ephemeral and should not be committed, while a few files are shared project artifacts that belong in the repo. Add this block to your project's .gitignore:
# impeccable-ignore-start
# Ephemeral output, runtime state, and per-dev overrides.
# Unanchored: .impeccable may sit at the repo root or under a nested
# workspace (apps/web/.impeccable/...); anchored patterns would miss it.
# Shared artifacts stay tracked: config.json, live/config.json,
# design.json, critique/*.md.
.impeccable/config.local.json
.impeccable/hook.cache.json
.impeccable/hook.pending.json
.impeccable/*.png
.impeccable/live/server.json
.impeccable/live/sessions/
.impeccable/live/previews/
.impeccable/live/annotations/
.impeccable/live/cache/
.impeccable/live/manual-edit-apply-transaction.json
.impeccable/live/manual-edit-events.jsonl
.impeccable/live/manual-edit-evidence/
.impeccable/live/pending-manual-edits.json
.impeccable/live/deferred-svelte-component-accepts.json
.impeccable/live/*.png
# impeccable-ignore-end
The block is wrapped in # impeccable-ignore-start / # impeccable-ignore-end markers so you can recognize and refresh it later. Patterns are unanchored on purpose: in a monorepo the active project (and its .impeccable/ directory) often lives under a nested workspace path like apps/web/, and a root-anchored pattern would miss it.
Keep these tracked (they are shared project artifacts, do not add them to .gitignore):
.impeccable/config.json(unified shared config).impeccable/live/config.json(live-mode framework wiring).impeccable/design.json(shared design spec).impeccable/critique/*.md(review reports)
If an ephemeral file (a screenshot, config.local.json) was committed before you added the block, .gitignore will not untrack it automatically. Run git rm --cached <path> to stop tracking it without deleting your local copy.
Design hook
On Claude Code, GitHub Copilot, Codex, and Cursor, npx impeccable install and npx impeccable update install a provider-native hook manifest along with the skill payload. The hook runs the Impeccable design detector on direct UI file edits and surfaces findings back into the agent flow. Claude Code, GitHub Copilot, and Codex surface findings after the edit. Cursor blocks bad proposed writes before they land.
Installed hook surfaces:
- Claude Code:
.claude/settings.local.json(gitignored, machine-local) runs${CLAUDE_PROJECT_DIR}/.claude/skills/impeccable/scripts/hook.mjs. A hook moved into the sharedsettings.jsonis honored in place. - GitHub Copilot:
.github/hooks/impeccable.json(committed, shared by the Copilot CLI and the cloud agent) runs.github/skills/impeccable/scripts/hook.mjs. The Copilot CLI activates it once the file is on the repository's default branch and the folder is trusted. - Cursor:
.cursor/hooks.jsonruns.cursor/skills/impeccable/scripts/hook-before-edit.mjs. - Codex:
.codex/hooks.jsonruns.agents/skills/impeccable/scripts/hook.mjs.
The installer preserves unrelated hook entries and settings. If a hook manifest is malformed, install/update aborts by default; rerun with --force to back up the malformed file as .bak and replace it.
On an interactive install/update, Impeccable explains the hook and offers to install it (default yes). Your choice is remembered per-developer in the gitignored .impeccable/config.local.json, so you are not asked again; --no-hooks skips it for that run without recording anything. Hook lifecycle settings live under the hook key of .impeccable/config.json; detector ignores live under detector, shared by /impeccable hooks and npx impeccable detect.
For debugging, set hook.auditLog in .impeccable/config.json to a path (or the legacy IMPECCABLE_HOOK_LOG env var) to write one NDJSON line per hook invocation. Leave it unset for normal use.
Codex requires one platform step that Impeccable cannot safely skip: open /hooks after install or update and approve the project hook. There is no Codex marketplace/plugin install flow for this hook.
Full hook docs: impeccable.style/docs/hooks.
Manual copy commands are fallback/debug instructions. The normal path is:
npx impeccable install
npx impeccable update
CLI
Impeccable includes a standalone CLI for detecting anti-patterns without an AI harness:
npx impeccable detect src/ # scan a directory
npx impeccable detect index.html # scan an HTML file
npx impeccable detect https://example.com # scan a URL (Puppeteer)
npx impeccable detect --json . # CI-friendly JSON output
npx impeccable detect --no-config src/ # raw scan, ignoring project config/context
npx impeccable ignores list # show detector ignores
npx impeccable ignores add-file "src/legacy/**"
npx impeccable ignores add-value overused-font Inter --reason "Brand font"
The detector catches 46 deterministic issues across AI slop (side-tab borders, purple gradients, bounce easing, dark glows) and general design quality (line length, cramped padding, small touch targets, skipped headings, and more).
By default, detect respects the same .impeccable/config.json and .impeccable/config.local.json detector config as the design hook: detector.ignoreRules, detector.ignoreFiles, detector.ignoreValues, and detector.designSystem.enabled. Hook lifecycle settings such as hook.enabled only affect automatic hook execution.
For a waiver that should travel with one file instead of the repo config, add an inline comment in the file: <!-- impeccable-disable overused-font: exported brand doc -->. The marker works in any comment syntax, scopes to the whole file (or one line with impeccable-disable-line / impeccable-disable-next-line), and is bypassed by --no-inline-ignores or --no-config.
Full detector docs: impeccable.style/docs/detector.
Supported Tools
- Cursor
- Claude Code
- GitHub Copilot
- Gemini CLI
- Codex CLI
- Grok Build
- OpenCode
- Pi
- Kiro
- Trae
- Rovo Dev
- Qoder
Community & Ecosystem
Join the community and ecosystem conversations:
- GitHub Discussions: file bugs, request features, and help newcomers.
- Impeccable on npm: grab the CLI, follow releases, and star the package.
- Follow @pbakaus on Twitter for release notes, sample lint reports, and video highlights of new rules.
Contributing
See DEVELOP.md for contributor guidelines and build instructions.
License
Apache 2.0. See LICENSE.
Created by Paul Bakaus