Agent skill

Bulletproof Frontend

Bulletproof CSS and frontend design principles from "Handcrafted CSS" by Dan Cederholm.

Install Bulletproof Frontend

skills CLI

$ npx skills add aaddrick/claude-pipeline --skill bulletproof-frontend -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI

$ gh skill install aaddrick/claude-pipeline bulletproof-frontend --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy

$ git clone --depth 1 https://github.com/aaddrick/claude-pipeline.git skills-src && mkdir -p .claude/skills && cp -r skills-src/.claude/skills/bulletproof-frontend .claude/skills/bulletproof-frontend && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Paste into Claude Code

Install the "bulletproof-frontend" agent skill from https://github.com/aaddrick/claude-pipeline/tree/main/.claude/skills/bulletproof-frontend into .claude/skills/bulletproof-frontend/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "bulletproof-frontend", then confirm the skill loads.

Claude Code copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

$skill-installer

$skill-installer install https://github.com/aaddrick/claude-pipeline/tree/main/.claude/skills/bulletproof-frontend

Type this inside Codex. $skill-installer <name> installs a curated skill from openai/skills. The installer writes to $CODEX_HOME/skills (default ~/.codex/skills). Restart Codex if the skill does not show up.

skills CLI

$ npx skills add aaddrick/claude-pipeline --skill bulletproof-frontend -a codex

Project install goes to .agents/skills/; add -g for ~/.codex/skills/.

GitHub CLI

$ gh skill install aaddrick/claude-pipeline bulletproof-frontend --agent codex

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/aaddrick/claude-pipeline.git skills-src && mkdir -p .agents/skills && cp -r skills-src/.claude/skills/bulletproof-frontend .agents/skills/bulletproof-frontend && rm -rf skills-src

Use ~/.agents/skills/ instead of .agents/skills for a personal install.

Codex skills documentation · loads skills from .agents/skills/

Paste into Codex

Install the "bulletproof-frontend" agent skill from https://github.com/aaddrick/claude-pipeline/tree/main/.claude/skills/bulletproof-frontend into .agents/skills/bulletproof-frontend/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "bulletproof-frontend", then confirm the skill loads.

Codex copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

skills CLI

$ npx skills add aaddrick/claude-pipeline --skill bulletproof-frontend -a cursor

Project install goes to .agents/skills/; add -g for ~/.cursor/skills/.

GitHub CLI

$ gh skill install aaddrick/claude-pipeline bulletproof-frontend --agent cursor

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/aaddrick/claude-pipeline.git skills-src && mkdir -p .cursor/skills && cp -r skills-src/.claude/skills/bulletproof-frontend .cursor/skills/bulletproof-frontend && rm -rf skills-src

Use ~/.cursor/skills/ instead of .cursor/skills for a personal install.

Cursor skills documentation · loads skills from .cursor/skills/, .agents/skills/, .claude/skills/, .codex/skills/

Paste into Cursor

Install the "bulletproof-frontend" agent skill from https://github.com/aaddrick/claude-pipeline/tree/main/.claude/skills/bulletproof-frontend into .cursor/skills/bulletproof-frontend/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "bulletproof-frontend", then confirm the skill loads.

Cursor copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

gemini skills install

$ gemini skills install https://github.com/aaddrick/claude-pipeline.git --path .claude/skills/bulletproof-frontend

--scope user (default) or --scope workspace; --path is the subfolder of the repo that holds the skill; --consent skips the security confirmation prompt.

skills CLI

$ npx skills add aaddrick/claude-pipeline --skill bulletproof-frontend -a gemini-cli

Project install goes to .agents/skills/; add -g for ~/.gemini/skills/.

GitHub CLI

$ gh skill install aaddrick/claude-pipeline bulletproof-frontend --agent gemini-cli

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/aaddrick/claude-pipeline.git skills-src && mkdir -p .gemini/skills && cp -r skills-src/.claude/skills/bulletproof-frontend .gemini/skills/bulletproof-frontend && rm -rf skills-src

Use ~/.gemini/skills/ instead of .gemini/skills for a personal install, then run /skills reload.

Gemini CLI skills documentation · loads skills from .gemini/skills/, .agents/skills/

Paste into Gemini CLI

Install the "bulletproof-frontend" agent skill from https://github.com/aaddrick/claude-pipeline/tree/main/.claude/skills/bulletproof-frontend into .gemini/skills/bulletproof-frontend/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "bulletproof-frontend", then confirm the skill loads.

Gemini CLI copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

GitHub CLI

$ gh skill install aaddrick/claude-pipeline bulletproof-frontend

Installs for Copilot at project scope by default; add --scope user for a personal install. Preview a skill first with gh skill preview. Needs GitHub CLI 2.90.0 or later (public preview).

skills CLI

$ npx skills add aaddrick/claude-pipeline --skill bulletproof-frontend -a github-copilot

Project install goes to .agents/skills/; add -g for ~/.copilot/skills/.

Manual copy

$ git clone --depth 1 https://github.com/aaddrick/claude-pipeline.git skills-src && mkdir -p .github/skills && cp -r skills-src/.claude/skills/bulletproof-frontend .github/skills/bulletproof-frontend && rm -rf skills-src

Use ~/.copilot/skills/ instead of .github/skills for a personal install. Commit .github/skills so cloud agent and code review can use it.

GitHub Copilot skills documentation · loads skills from .github/skills/, .claude/skills/, .agents/skills/

Paste into GitHub Copilot

Install the "bulletproof-frontend" agent skill from https://github.com/aaddrick/claude-pipeline/tree/main/.claude/skills/bulletproof-frontend into .github/skills/bulletproof-frontend/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "bulletproof-frontend", then confirm the skill loads.

GitHub Copilot copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

skills CLI

$ npx skills add aaddrick/claude-pipeline --skill bulletproof-frontend -a opencode

OpenCode documents no install command of its own. Project install goes to .agents/skills/; add -g for ~/.config/opencode/skills/.

GitHub CLI

$ gh skill install aaddrick/claude-pipeline bulletproof-frontend --agent opencode

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/aaddrick/claude-pipeline.git skills-src && mkdir -p .opencode/skills && cp -r skills-src/.claude/skills/bulletproof-frontend .opencode/skills/bulletproof-frontend && rm -rf skills-src

Use ~/.config/opencode/skills/ instead of .opencode/skills for a personal install.

OpenCode skills documentation · loads skills from .opencode/skills/, .claude/skills/, .agents/skills/

Paste into OpenCode

Install the "bulletproof-frontend" agent skill from https://github.com/aaddrick/claude-pipeline/tree/main/.claude/skills/bulletproof-frontend into .opencode/skills/bulletproof-frontend/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "bulletproof-frontend", then confirm the skill loads.

OpenCode copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

Facts

Skill name: bulletproof-frontend
GitHub stars: 130
Token cost: ~1k tokens
SKILL.md length: 310 words
Files: 6
Skills in repo: 12
Repo updated: Feb 25, 2026
First seen: Oct 7, 2026
Licence: MIT

At a glance

Bulletproof CSS and frontend design principles from "Handcrafted CSS" by Dan Cederholm.

Works in 3 steps: Bulletproof Design → Progressive Enrichment → Reevaluate Past Methods
Tasks that involve CSS and styling
SKILL.md covers Core Philosophy, The Three Pillars, Quick Reference and Modern CSS Essentials, plus 4 more sections
Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md

What it does

Bulletproof Frontend is an agent skill from aaddrick/claude-pipeline. Bulletproof CSS and frontend design principles from "Handcrafted CSS" by Dan Cederholm. Apply when writing CSS, HTML, Blade templates, or reviewing frontend code. CSS is king — refactor Tailwind when encountered.

Its SKILL.md is about 1k tokens, which your agent loads only when the skill is triggered. The skill folder holds 5 other files (for example `CLAUDE.md`, `accessibility-patterns.md` and `css-architecture.md`).

It sits in Frontend & Design, covering CSS and styling and Refactoring. It works with Tailwind CSS. The repository describes itself as: Portable Claude Code multi-agent pipeline - skills, agents, hooks, orchestration scripts, and quality gates. The licence is MIT.

When your agent uses it

Tasks that involve CSS and styling
Tasks that involve Refactoring

Example prompts

“Handcrafted CSS”
“/bulletproof-frontend”

Workflow steps

3 steps, taken from the step headings in SKILL.md.

Bulletproof Design
Progressive Enrichment
Reevaluate Past Methods

What it can do on your machine

Read from SKILL.md and the folder at commit 402eac7. It shows what the files ask for, not the result of running them.

Tool permissions
Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.
From allowed-tools in the SKILL.md frontmatter.
Runs code
No scripts in the folder and no shell commands in SKILL.md (its code samples are css and blade).
From the folder's file list and the shell code blocks in SKILL.md.
Network
No URLs in SKILL.md.
From URLs in SKILL.md, links to its own repository left out.
Credentials
Names no API keys, tokens, secrets or passwords.
From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Bulletproof Frontend loads about 1k tokens when it runs. Until then it costs about 58 tokens; SKILL.md has 310 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it: ~58
When it runs · the whole SKILL.md, loaded when a task matches: ~1k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from aaddrick/claude-pipeline at commit 402eac7, republished under its MIT licence (© aaddrick). 310 words, ~1,007 tokens.

Download SKILL.mdSave it as .claude/skills/bulletproof-frontend/SKILL.md (or your agent's skills folder). This skill also uses 5 other files; get the full folder from GitHub.

name: bulletproof-frontend
description: Bulletproof CSS and frontend design principles from "Handcrafted CSS" by Dan Cederholm. Apply when writing CSS, HTML, Blade templates, or reviewing frontend code. CSS is king — refactor Tailwind when encountered.

Bulletproof Frontend Design

CSS is king. Semantic, maintainable CSS over utility-class frameworks. When you encounter Tailwind, refactor it to proper CSS.

Design Values: For spacing scales, typography sizes, color palettes, contrast ratios, and component specifications, see ui-design-fundamentals. This skill focuses on CSS implementation patterns.

Core Philosophy

"Always ask: What happens if...?" — Design for the unexpected. Build interfaces that remain functional and readable regardless of content length, text size, browser, or device.

The Three Pillars

1. Bulletproof Design

Design for flexibility, not fixed scenarios
Test with varying text sizes and content lengths
Use relative units (em, %, rem) over fixed pixels

2. Progressive Enrichment

Reward capable browsers with advanced CSS
Websites don't need to look identical in every browser — they need to be functional
Use modern CSS with appropriate fallbacks

3. Reevaluate Past Methods

Question whether old hacks are still necessary
Simplify where new CSS features allow
Refactor utility frameworks to semantic CSS

Quick Reference

Pattern	When to Use
CSS custom properties	Theming, spacing, colors
BEM naming	Component class structure
Cascade layers	Managing specificity
Container queries	Component-based responsiveness
:has() selector	Parent/sibling selection
CSS nesting	Organizing related styles

Modern CSS Essentials

css

/* :has() — Style based on children */
.card:has(img) { padding-top: 0; }
.form:has(:invalid) { border-color: var(--color-error); }

/* Container queries — Component responsiveness */
.container { container-type: inline-size; }
@container (min-width: 400px) { .card { display: flex; } }

/* CSS nesting — Clean organization */
.card {
    padding: var(--space-md);
    &:hover { box-shadow: var(--shadow-lg); }
    & .card__title { font-weight: var(--font-bold); }
}

/* Cascade layers — Controlled specificity */
@layer reset, base, components, utilities;

Tailwind → Semantic CSS

blade

{{-- BEFORE: Utility classes --}}
<div class="flex items-center p-4 bg-white rounded-lg shadow">

{{-- AFTER: Semantic CSS --}}
<div class="card">

css

.card {
    display: flex;
    align-items: center;
    padding: var(--space-md);
    background: var(--color-surface);
    border-radius: var(--radius-lg);
    box-shadow: var(--shadow-md);
}

CSS Approach	Tailwind
Readable HTML	Bloated class attributes
Styles in one place	Scattered in markup
Easy to refactor	Find-and-replace nightmare
Cacheable stylesheets	Repeated classes

Reference Files

File	Content
css-architecture.md	Custom properties, BEM, layers, file organization
accessibility-patterns.md	Focus, screen readers, motion, dark mode
responsive-patterns.md	Breakpoints, container queries, fluid sizing
reference.md	Complete patterns and Blade components

Project Style Guide

Project-specific implementation: docs/STYLEGUIDE.md

Contains the complete design system for the application:

Design tokens (colors, spacing, typography)
Component patterns (buttons, cards, alerts, tables)
Blade component documentation
Dark mode implementation
Accessibility requirements

Always consult the style guide when implementing UI to ensure consistency with existing patterns.

ui-design-fundamentals — Design values: spacing scales, type scales, colors, contrast ratios, component anatomy (buttons, forms, cards, etc.)

Files

SKILL.md and 5 other files in .claude/skills/bulletproof-frontend of aaddrick/claude-pipeline.

SKILL.md
CLAUDE.md
accessibility-patterns.md
css-architecture.md
reference.md
responsive-patterns.md

Open the folder on GitHubat commit 402eac7

Compare with similar skills

Bulletproof Frontend next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.

Bulletproof Frontend compared with similar skills
Skill	Stars	Used in	Tokens	Auto-check	Licence	Repo updated
Bulletproof Frontend this skillaaddrick/claude-pipeline	130	—	~1k	Automated safety check: Pass	MIT	7 mo ago
Unslop UIJCarterJohnson/vibecoded-design-tells	511	—	~1.9k	Automated safety check: Pass	Custom licence	3 mo ago
Frontend Code Stylemailtrap/mailtrap-local	109	—	~2.7k	Automated safety check: Pass	MIT	1 mo ago
Frontend UI FunctionalvictorGPT/vibeusage	131	—	~939	Automated safety check: Pass	MIT	2 mo ago
Frontend UI Foundryjiushiwon/wg-skills	112	—	~1.4k	Automated safety check: Pass	Apache-2.0	yesterday
Tailwind V4mastra-ai/mastra	29k	—	~2.5k	Automated safety check: Pass	Custom licence	today

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All 12 skills in this repo

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Adapting Claude Pipeline
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Investigating Codebase For User Stories
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Review UI
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Using Git Worktrees
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Implement Issue
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Works with

Tailwind CSS

Questions about Bulletproof Frontend

What does Bulletproof Frontend do?

Bulletproof CSS and frontend design principles from "Handcrafted CSS" by Dan Cederholm. Bulletproof Frontend is an agent skill from aaddrick/claude-pipeline. Bulletproof CSS and frontend design principles from "Handcrafted CSS" by Dan Cederholm.

When should I use Bulletproof Frontend?

Bulletproof Frontend fits situations like: tasks that involve CSS and styling; tasks that involve Refactoring.

How do I install Bulletproof Frontend in Claude Code?

Run `npx skills add aaddrick/claude-pipeline --skill bulletproof-frontend -a claude-code`. Or copy the skill folder (.claude/skills/bulletproof-frontend in aaddrick/claude-pipeline) into .claude/skills/bulletproof-frontend in your project. Claude Code loads it when a task matches its description.

How do I install Bulletproof Frontend in Codex?

Run `npx skills add aaddrick/claude-pipeline --skill bulletproof-frontend -a codex`. Or copy the skill folder (.claude/skills/bulletproof-frontend in aaddrick/claude-pipeline) into .agents/skills/bulletproof-frontend in your project. Codex loads it when a task matches its description.

Can I use Bulletproof Frontend in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add aaddrick/claude-pipeline --skill bulletproof-frontend -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/bulletproof-frontend, .gemini/skills/bulletproof-frontend, .github/skills/bulletproof-frontend and .opencode/skills/bulletproof-frontend in your project.

What does Bulletproof Frontend need to run?

SKILL.md names no scripts, command-line tools or credentials: Bulletproof Frontend is instructions for the agent only.

Does Bulletproof Frontend access the network?

SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.

Is Bulletproof Frontend safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.

What licence does Bulletproof Frontend use?

Bulletproof Frontend is published under the MIT licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Bulletproof Frontend use?

About 1k tokens (SKILL.md is roughly 4k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.

What are the alternatives to Bulletproof Frontend?

Skills that share tags, products or a category with Bulletproof Frontend: Unslop UI (JCarterJohnson/vibecoded-design-tells, 511 stars), Frontend Code Style (mailtrap/mailtrap-local, 109 stars), Frontend UI Functional (victorGPT/vibeusage, 131 stars) and Frontend UI Foundry (jiushiwon/wg-skills, 112 stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Bulletproof Frontend?

aaddrick (a GitHub user) maintains it in aaddrick/claude-pipeline, which has 130 GitHub stars. The repository holds 12 skills in this directory. The repository was last updated on February 25, 2026.

Source: aaddrick/claude-pipeline on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.

Install Bulletproof Frontend

Facts

At a glance

What it does

When your agent uses it

Example prompts

Workflow steps

What it can do on your machine

Tool permissions

Runs code

Network

Credentials

Context cost

Safety

SKILL.md

Bulletproof Frontend Design

Core Philosophy

The Three Pillars

1. Bulletproof Design

2. Progressive Enrichment

3. Reevaluate Past Methods

Quick Reference

Modern CSS Essentials

Tailwind → Semantic CSS

Reference Files

Project Style Guide

Related Skills

Files

Compare with similar skills

Similar skills

More from aaddrick/claude-pipeline

Related

Questions about Bulletproof Frontend