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Agent skill

CSS Expert

by RightNow-AI in RightNow-AI/openfang

CSS expert for flexbox, grid, animations, responsive design, and modern layout techniques

Apache-2.0Auto-check passedFrontend & Design

Install CSS Expert

skills CLI
$ npx skills add RightNow-AI/openfang --skill css-expert -a claude-code

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

GitHub CLI
$ gh skill install RightNow-AI/openfang css-expert --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/RightNow-AI/openfang.git skills-src && mkdir -p .claude/skills && cp -r skills-src/crates/openfang-skills/bundled/css-expert .claude/skills/css-expert && 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/

Facts

Skill name
css-expert
GitHub stars
18k
Token cost
~788 tokens
SKILL.md length
391 words
Files
1
Skills in repo
68
Repo updated
First seen
Licence
Apache-2.0

At a glance

CSS expert for flexbox, grid, animations, responsive design, and modern layout techniques

  • Tasks that involve CSS and styling
  • SKILL.md covers Key Principles, Techniques, Common Patterns and Pitfalls to Avoid
  • Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md
  • Tasks that involve Responsive design

What it does

CSS Expert is an agent skill from RightNow-AI/openfang. CSS expert for flexbox, grid, animations, responsive design, and modern layout techniques

Its SKILL.md is about 790 tokens, which your agent loads only when the skill is triggered. It is a single SKILL.md file with no bundled scripts.

It sits in Frontend & Design, covering CSS and styling and Responsive design. The repository describes itself as: Open-source Agent Operating System. The licence is Apache-2.0.

When your agent uses it

  • Tasks that involve CSS and styling
  • Tasks that involve Responsive design

Example prompts

  • “/css-expert”

What it can do on your machine

Read from SKILL.md and the folder at commit acf2587. 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.

    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

CSS Expert loads about 788 tokens when it runs. Until then it costs about 25 tokens; SKILL.md has 391 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~25
When it runs · the whole SKILL.md, loaded when a task matches
~788

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 RightNow-AI/openfang at commit acf2587, republished under its Apache-2.0 licence (© RightNow-AI). 391 words, ~788 tokens.

Download SKILL.mdSave it as .claude/skills/css-expert/SKILL.md (or your agent's skills folder).
name
css-expert
description
CSS expert for flexbox, grid, animations, responsive design, and modern layout techniques

CSS Expert

A front-end layout specialist with deep command of modern CSS, from flexbox and grid to container queries and cascade layers. This skill provides precise, standards-compliant guidance for building responsive, accessible, and maintainable user interfaces using the latest CSS specifications and best practices.

Key Principles

  • Use flexbox for one-dimensional layouts (rows or columns) and CSS Grid for two-dimensional layouts (rows and columns simultaneously)
  • Embrace custom properties (CSS variables) for theming, spacing scales, and any value that repeats or needs runtime adjustment
  • Design mobile-first with min-width media queries, layering complexity as viewport size increases
  • Prefer logical properties (inline-start, block-end) over physical ones (left, bottom) for internationalization-ready layouts
  • Leverage the cascade intentionally with @layer declarations to control specificity without resorting to !important

Techniques

  • Use flexbox justify-content and align-items for main-axis and cross-axis alignment; flex-wrap with gap for fluid card layouts
  • Define CSS Grid layouts with grid-template-areas for named regions, and auto-fit/auto-fill with minmax() for responsive grids without media queries
  • Create design tokens as custom properties on :root (--color-primary, --space-md) and override them in scoped selectors or media queries
  • Use @container queries to style components based on their parent container size rather than the viewport
  • Build animations with @keyframes and animation shorthand; prefer transform and opacity for GPU-accelerated, jank-free motion
  • Apply transitions on interactive states (hover, focus-visible) with appropriate duration (150-300ms) and easing functions
  • Use the :has() selector for parent-aware styling, :is()/:where() for grouping selectors with controlled specificity
Show full SKILL.md (155 more words)Show less

Common Patterns

  • Holy Grail Layout: CSS Grid with grid-template-rows (auto 1fr auto) and grid-template-columns (sidebar content sidebar) for header/footer/sidebar page structures
  • Fluid Typography: clamp(1rem, 2.5vw, 2rem) for font sizes that scale smoothly between minimum and maximum values without breakpoints
  • Aspect Ratio Boxes: Use the aspect-ratio property directly instead of the legacy padding-bottom hack for responsive media containers
  • Dark Mode Toggle: Define color tokens as custom properties, swap them inside a prefers-color-scheme media query or a data-theme attribute selector

Pitfalls to Avoid

  • Do not use fixed pixel widths for layout containers; prefer percentage, fr units, or min/max constraints for fluid responsiveness
  • Do not stack z-index values arbitrarily; establish a z-index scale in custom properties and document each layer's purpose
  • Do not rely on vendor prefixes without checking current browser support; tools like autoprefixer handle this systematically
  • Do not nest selectors excessively in preprocessors, as the generated CSS becomes highly specific and difficult to maintain or override

© RightNow-AI, Apache-2.0. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

Just SKILL.md in crates/openfang-skills/bundled/css-expert of RightNow-AI/openfang.

Open the folder on GitHubat commit acf2587

Compare with similar skills

CSS Expert 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.

CSS Expert compared with similar skills
SkillStarsUsed inTokensAuto-checkLicenceRepo updated
CSS Expert this skillRightNow-AI/openfang18k—~788Automated safety check: PassApache-2.0
UI StylingOhh-889/skyroc79513 repos~2.5kAutomated safety check: PassMIT
Frontend Design Routercode-yeongyu/oh-my-openagent70k—~5.3kAutomated safety check: PassCustom licence
Refero Designreferodesign/refero_skill295—~5.3kAutomated safety check: PassMIT
Tailwind CSS Patternsever-works/ever-works1583 repos~1.6kAutomated safety check: NotesAGPL-3.0
Good CSSvojtaholik/good-css120—~1.2kAutomated safety check: PassMIT

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Categories

Questions about CSS Expert

What does CSS Expert do?

CSS expert for flexbox, grid, animations, responsive design, and modern layout techniques. CSS Expert is an agent skill from RightNow-AI/openfang.

When should I use CSS Expert?

CSS Expert fits situations like: tasks that involve CSS and styling; tasks that involve Responsive design.

How do I install CSS Expert in Claude Code?

Run `npx skills add RightNow-AI/openfang --skill css-expert -a claude-code`. Or copy the skill folder (crates/openfang-skills/bundled/css-expert in RightNow-AI/openfang) into .claude/skills/css-expert in your project. Claude Code loads it when a task matches its description.

How do I install CSS Expert in Codex?

Run `npx skills add RightNow-AI/openfang --skill css-expert -a codex`. Or copy the skill folder (crates/openfang-skills/bundled/css-expert in RightNow-AI/openfang) into .agents/skills/css-expert in your project. Codex loads it when a task matches its description.

Can I use CSS Expert 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 RightNow-AI/openfang --skill css-expert -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/css-expert, .gemini/skills/css-expert, .github/skills/css-expert and .opencode/skills/css-expert in your project.

What does CSS Expert need to run?

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

Does CSS Expert 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 CSS Expert 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 CSS Expert use?

CSS Expert is published under the Apache-2.0 licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does CSS Expert use?

About 788 tokens (SKILL.md is roughly 3.2k 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 CSS Expert?

Skills that share tags, products or a category with CSS Expert: UI Styling (Ohh-889/skyroc, 795 stars), Frontend Design Router (code-yeongyu/oh-my-openagent, 70k stars), Refero Design (referodesign/refero_skill, 295 stars) and Tailwind CSS Patterns (ever-works/ever-works, 158 stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains CSS Expert?

RightNow-AI (a GitHub organization) maintains it in RightNow-AI/openfang, which has 18,213 GitHub stars. The repository holds 68 skills in this directory. The repository was last updated on July 2, 2026.

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