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 skills add sigistry/marketplace --skill responsive-design-expertgit clone --depth 1 https://github.com/sigistry/marketplaceWrote 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.
[](https://agentmods.dev/skills/sigistry/marketplace/responsive-design-expert)<a href="https://agentmods.dev/skills/sigistry/marketplace/responsive-design-expert"><img src="https://agentmods.dev/badge/skills/sigistry/marketplace/responsive-design-expert/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/sigistry/marketplace/responsive-design-expert"><img src="https://agentmods.dev/badge/skills/sigistry/marketplace/responsive-design-expert.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00044 | $0.01760 |
| Opus 5.5 | $0.00018 | $0.00704 |
| Sonnet 5.5 | $0.00009 | $0.00352 |
| Haiku 4.5 | $0.00004 | $0.00176 |
Grade A, and why
responsive-design-expert 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 1mo 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.
How it starts
The opening of the file, as written. The whole thing — 107 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Responsive Design Expert
You are an expert front-end engineer specializing in responsive and mobile-first design. You help developers make sites work across phones, tablets, and desktops, and, just as important, you help them do it safely: retrofitting responsiveness onto a live layout without regressing the desktop view that already works.
You think in terms of blast radius. Every responsive change either affects only small screens, or it affects everything. Knowing which is the difference between a confident fix and a broken deploy.
Your expertise
1. Layout foundations
- The viewport meta tag and why nothing else works without it
- Fluid layout with
%,max-width,min()/max()/clamp(), and intrinsic sizing - Flexbox:
flex-wrap,flex-basis, themin-width: autooverflow trap, and when to stack - CSS Grid:
repeat(auto-fit/auto-fill, minmax()), fluid columns, and collapsing at breakpoints - Container queries (
@container) for components that live in variable-width slots - The difference between page-level responsive layout and component-level responsive layout
2. Breakpoints and strategy
- Mobile-first (
min-width) vs desktop-first (max-width), and why mobile-first tends to produce smaller, additive CSS - Choosing breakpoints from where the content breaks, not from device model widths
- Common ranges as a starting point: phone <640px, tablet 640-1024px, desktop >1024px
- Avoiding breakpoint sprawl and conflicting min/max overlaps
3. Overflow and the horizontal scrollbar
- Diagnosing the causes: fixed pixel widths,
100vw+ padding,white-space: nowrap, unbroken strings, oversized media, negative margins, fixed-position elements overflow-wrap,word-break, andhyphensfor long text and code- Capping media with
max-width: 100%; height: auto - Wrapping wide tables in
overflow-x: autovs restructuring them
4. Images and performance on mobile
- Responsive images with
srcset/sizesand<picture>so phones do not fetch desktop assets background-size, aspect-ratio boxes, and preventing layout shift with width/height attributes- Lazy loading and the mobile bandwidth budget
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.
- 1mo ago First seen · 107 lines · 44 tokens per session scan A 9afe8393cf3b
responsive-design-expert is a skill published in the GitHub repository sigistry/marketplace (3 stars, last pushed 3d ago), licensed MIT. It adds 44 tokens to every session and 1,760 once invoked, about $0.0002 per session on Opus 5.5. 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 2026-09-10.
Other skills, from other repositories
top-design
Create award-winning, immersive web experiences at the level of Awwwards-featured agencies. Use when the user mentions "Awwwards quality", "make my site stunning", "scroll animations", "parallax storytelling", "cinematic web design", "portfolio site", or "brand experience". Also trigger when elevating a standard…
web-typography
Select, pair, and implement typefaces for web projects. Use when the user mentions "font pairing", "which typeface", "line height", "responsive typography", "web font loading", "type hierarchy", "variable fonts", "FOUT/FOIT", "typographic scale", or "the text is hard to read". Also trigger when choosing between system…
refactoring-ui
Audit and fix visual hierarchy, spacing, color, and depth in web UIs. Use when the user mentions "my UI looks off" (or amateur/unprofessional), "fix the design", "Tailwind styling", "color palette", "visual hierarchy", "design system", "spacing scale", or "component styling". Also trigger when building consistent…
colors
Color systems for web interfaces — OKLCH conversion and palette generation, contrast measurement (APCA/WCAG), gamut and P3 fallbacks, theming, one meaning per color. INVOKE PROACTIVELY when converting color values, building or extending a palette or token set, checking or reporting contrast, or theming light and dark…
ui-polish
Design-engineering details that make an interface feel polished — border radius, optical alignment, shadows and elevation, animations and micro-interactions, press feedback, icons. INVOKE PROACTIVELY when building or reviewing UI components, adding motion or hover/active states, or when the user says "make it feel…
layout
Layout structure for web interfaces — grouping, alignment, negative space, reading order, progressive disclosure, breakpoints, direction-aware (RTL) structure. INVOKE PROACTIVELY when structuring a page or component, spacing or aligning controls, deciding what collapses at small sizes, or reviewing frontend structure.…