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.
npx agentmods add skills/justanesta/claude-code-resources/webdev-html-css-patternsnpx skills add justanesta/claude-code-resources --skill webdev-html-css-patternsgit clone --depth 1 https://github.com/justanesta/claude-code-resourcesWhat 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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5 | $0.00031 | $0.01999 |
| Opus 5 | $0.00015 | $0.01000 |
| Sonnet 5 | $0.00006 | $0.00400 |
| Haiku 4.5 | $0.00003 | $0.00200 |
Grade A, and why
webdev-html-css-patterns 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 yesterday.
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.
How it starts
The opening of the file, as written. The whole thing — 251 lines — stays where its author put it; the contents beside it link to each section on GitHub.
HTML & CSS Patterns
Core Principles
- Semantic HTML First -- Use elements that convey meaning (
<article>,<nav>,<aside>) rather than generic<div>and<span>. Semantic markup improves accessibility, SEO, and maintainability. - Responsive by Default -- Design for all viewports from the start using fluid units, modern layout systems, and progressive enhancement rather than retrofitting breakpoints.
- Accessibility as a Requirement -- Every interface must be navigable by keyboard, screen reader, and assistive technology. ARIA supplements semantic HTML; it does not replace it.
- CSS Layout over Hacks -- Use Grid and Flexbox for layout. Avoid floats, negative margins, and absolute positioning for page-level structure.
- Progressive Enhancement -- Build a functional baseline with HTML, layer on styling with CSS, and enhance with JavaScript only when necessary.
Semantic HTML5 Structure
Use landmark elements to define page regions. Screen readers and search engines rely on this hierarchy.
<body>
<header role="banner">
<nav aria-label="Primary navigation">
<ul>
<li><a href="/">Home</a></li>
<li><a href="/about">About</a></li>
</ul>
</nav>
</header>
<main id="main-content">
<article>
<h1>Article Heading</h1>
<section aria-labelledby="section-title">
<h2 id="section-title">Section Title</h2>
<p>Content goes here.</p>
</section>
</article>
<aside aria-label="Related content">
<h2>Related Links</h2>
</aside>
</main>
<footer role="contentinfo">
<p>© 2026 Company Name</p>
</footer>
</body>
See semantic-html-patterns for: form patterns, table markup, meta tags, SEO elements, and content sectioning rules.
CSS Grid Layout
Grid is the primary tool for two-dimensional layouts. Define explicit tracks or let the browser auto-place items.
/* Responsive card grid with auto-fit */
.card-grid {
display: grid;
grid-template-columns: repeat(auto-fit, minmax(min(100%, 300px), 1fr));
gap: 1.5rem;
padding: 1.5rem;
}
/* Named grid areas for page layout */
.page-layout {
display: grid;
grid-template-areas:
"header header"
"sidebar main"
"footer footer";
grid-template-columns: 250px 1fr;
grid-template-rows: auto 1fr auto;
min-height: 100dvh;
}
.page-layout > header { grid-area: header; }
.page-layout > aside { grid-area: sidebar; }
.page-layout > main { grid-area: main; }
.page-layout > footer { grid-area: footer; }
What ships with it
5 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
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.
- yesterday First seen · 251 lines · 31 tokens per session scan A 953d6cb5525f
webdev-html-css-patterns is a skill published in the GitHub repository justanesta/claude-code-resources (2 stars, last pushed 4mo ago), licensed MIT. It adds 31 tokens to every session and 1,999 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.
Other skills, from other repositories
systematic-debugging
Use when encountering any bug, test failure, or unexpected behavior, before proposing fixes.
next-cache-components-adoption
Turn on Cache Components in a Next.js app and resolve the blocking routes it surfaces. Use when the user wants to enable, adopt, or migrate to Cache Components, flip the cacheComponents flag, work through a flood of blocking-prerender / instant validation errors, run the cache-components-instant-false codemod, or…
babysit-pr
Babysit a GitHub pull request after creation by continuously polling review comments, CI checks/workflow runs, and mergeability state until the PR is merged/closed or user help is required. Diagnose failures, retry likely flaky failures up to 3 times, auto-fix/push branch-related issues when appropriate, and keep…
imagegen
Generate or edit raster images when the task benefits from AI-created bitmap visuals such as photos, illustrations, textures, sprites, mockups, or transparent-background cutouts. Use when Codex should create a brand-new image, transform an existing image, or derive visual variants from references, and the output…
cpu-profile-analysis
Analyze V8/Chrome CPU profiles (.cpuprofile) and DevTools trace files (Trace-.json). Use when: profiling performance, investigating slow functions, comparing code paths, finding bottlenecks, analyzing timeToRequest, understanding call trees from sampling profiler data, analyzing layout/paint/rendering, investigating…
next-cache-components-optimizer
Drive a Next.js route to instant navigation by setting up an agentic loop, under Cache Components / PPR, on initial load (hard navigation) and client-side navigation (soft navigation). Encode the goal as a failing @next/playwright instant() e2e and work it to green, one verified route at a time; the shipped test then…