responsive-design-advisor

responsive-design-advisor is a skill for Claude Code from armanzeroeight/fastagent-plugins. It costs 37 tokens per session (2,173 once invoked), scanned A, original, MIT.

A guide for building layouts that adapt to phones, tablets, and desktops. It explains breakpoints, mobile-first design, flexible units, CSS Grid, and Flexbox.

In plain words
What is it for?
Use it to choose breakpoints, build flexible grids, create mobile-first layouts, and test designs across screen sizes.
Why use it?
It helps prevent layouts from breaking when screen sizes change. It provides a way to organize styles for different devices.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin.

Part of the frontend-developer plugin — 3 skills shipped together

Good fit Use it to choose breakpoints, build flexible grids, create mobile-first layouts, and…

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/armanzeroeight/fastagent-plugins/responsive-design-advisor
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 armanzeroeight/fastagent-plugins --skill responsive-design-advisor
Clone the repo
git clone --depth 1 https://github.com/armanzeroeight/fastagent-plugins

Made for: Claude Code.

Or install frontend-developer, the plugin that ships this one along with the rest of its 3 skills.

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 responsive-design-advisor

README.md
[![agentmods](https://agentmods.dev/badge/skills/armanzeroeight/fastagent-plugins/responsive-design-advisor.svg)](https://agentmods.dev/skills/armanzeroeight/fastagent-plugins/responsive-design-advisor)
Your own site
<a href="https://agentmods.dev/skills/armanzeroeight/fastagent-plugins/responsive-design-advisor"><img src="https://agentmods.dev/badge/skills/armanzeroeight/fastagent-plugins/responsive-design-advisor.svg" alt="Measured on agentmods" height="20"></a>
Per session 37 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,173 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 original No closer match found 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 $0.00037 $0.02173
Opus 5 $0.00018 $0.01086
Sonnet 5 $0.00007 $0.00435
Haiku 4.5 $0.00004 $0.00217

Measured 3d ago against content hash 3a13cd13c7c0, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

responsive-design-advisor 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 3d 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.

plugins/frontend-developer/skills/responsive-design-advisor/SKILL.md · 447 lines

How it starts

The opening of the file, as written. The whole thing — 447 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Responsive Design Advisor

Design responsive layouts that work across all device sizes.

Quick Start

Use mobile-first approach, flexible units (rem, %), CSS Grid/Flexbox, and test on real devices.

Instructions

Mobile-First Approach

Start with mobile, enhance for larger screens:

/* Base styles (mobile) */
.container {
  padding: 1rem;
}

/* Tablet */
@media (min-width: 768px) {
  .container {
    padding: 2rem;
  }
}

/* Desktop */
@media (min-width: 1024px) {
  .container {
    padding: 3rem;
    max-width: 1200px;
    margin: 0 auto;
  }
}

Common Breakpoints

Standard breakpoints:

/* Mobile: 0-639px (default) */

/* Tablet: 640px+ */
@media (min-width: 640px) { }

/* Laptop: 1024px+ */
@media (min-width: 1024px) { }

/* Desktop: 1280px+ */
@media (min-width: 1280px) { }

/* Large: 1536px+ */
@media (min-width: 1536px) { }

Tailwind breakpoints:

<div className="
  w-full          // Mobile
  md:w-1/2        // Tablet
  lg:w-1/3        // Desktop
">
  Content
</div>

Flexible Layouts

CSS Grid:

.grid {
  display: grid;
  gap: 1rem;
  
  /* Mobile: 1 column */
  grid-template-columns: 1fr;
}

@media (min-width: 768px) {
  .grid {
    /* Tablet: 2 columns */
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (min-width: 1024px) {
  .grid {
    /* Desktop: 3 columns */
    grid-template-columns: repeat(3, 1fr);
  }
}

Auto-fit grid:

.grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 1rem;
}

Flexbox:

.flex-container {
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
}

.flex-item {
  flex: 1 1 100%; /* Mobile: full width */
}

@media (min-width: 768px) {
  .flex-item {
    flex: 1 1 calc(50% - 0.5rem); /* Tablet: 2 columns */
  }
}

@media (min-width: 1024px) {
  .flex-item {
    flex: 1 1 calc(33.333% - 0.667rem); /* Desktop: 3 columns */
  }
}

Responsive Typography

Fluid typography:

h1 {
  font-size: clamp(2rem, 5vw, 4rem);
}

p {
  font-size: clamp(1rem, 2vw, 1.125rem);
}

Read the full file on GitHub · 447 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. 3d ago First seen · 447 lines · 37 tokens per session scan A 3a13cd13c7c0

Subscribe to this mod's changes

responsive-design-advisor is a skill published in the GitHub repository armanzeroeight/fastagent-plugins (29 stars, last pushed 1mo ago), licensed MIT. It adds 37 tokens to every session and 2,173 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 2026-09-03.

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