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Agent skill

CSS At Property

by thedaviddias in thedaviddias/Front-End-Checklist

A skill your agent uses when implementing animated gradients, complex CSS transitions that involve custom property values, or building a typed design token system where custom property misuse should…

MITAuto-check passedFrontend & Design

Install CSS At Property

skills CLI
$ npx skills add thedaviddias/Front-End-Checklist --skill css-at-property -a claude-code

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

GitHub CLI
$ gh skill install thedaviddias/Front-End-Checklist css-at-property --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/thedaviddias/Front-End-Checklist.git skills-src && mkdir -p .claude/skills && cp -r skills-src/skills/css-at-property .claude/skills/css-at-property && 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-at-property
GitHub stars
74k
Token cost
~602 tokens
SKILL.md length
255 words
Files
2 (incl. references)
Skills in repo
390
Repo updated
First seen
Licence
MIT

At a glance

A skill your agent uses when implementing animated gradients, complex CSS transitions that involve custom property values, or building a typed design token system where custom property misuse should…

  • Implementing animated gradients
  • SKILL.md covers Quick Reference, Check, Fix and Explain, plus 1 more section
  • Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md
  • Complex CSS transitions that involve custom property values

What it does

CSS At Property is an agent skill from thedaviddias/Front-End-Checklist. Use when implementing animated gradients, complex CSS transitions that involve custom property values, or building a typed design token system where custom property misuse should produce visible errors.

Its SKILL.md is about 600 tokens, which your agent loads only when the skill is triggered. The skill folder holds 2 other files, including reference files (for example `references/rule.md`).

It sits in Frontend & Design, covering Design tokens. The repository describes itself as: 🗂 The essential checklist for modern web development, for humans and AI agents. The licence is MIT.

When your agent uses it

  • Implementing animated gradients
  • Complex CSS transitions that involve custom property values
  • Building a typed design token system where custom property misuse should produce visible errors

Example prompts

  • “/css-at-property”

What it can do on your machine

Read from SKILL.md and the folder at commit e8d14d0. 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

    Links to these hosts (documentation or services it may open):

    • frontendchecklist.io

    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 At Property loads about 602 tokens when it runs, and up to ~2.3k if it reads all its reference files. Until then it costs about 55 tokens; SKILL.md has 255 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~55
When it runs · the whole SKILL.md, loaded when a task matches
~602
With references · SKILL.md plus every file in references/, read only if the agent opens them
~2.3k

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 thedaviddias/Front-End-Checklist at commit e8d14d0, republished under its MIT licence (© thedaviddias). 255 words, ~602 tokens.

Download SKILL.mdSave it as .claude/skills/css-at-property/SKILL.md (or your agent's skills folder). This skill also uses 1 other file; get the full folder from GitHub.
name
css-at-property
description
Use when implementing animated gradients, complex CSS transitions that involve custom property values, or building a typed design token system where custom property misuse should produce visible errors.
metadata.category
css
metadata.priority
low
metadata.difficulty
advanced
metadata.estimatedTime
30
metadata.source
frontendchecklist.io
metadata.url
https://frontendchecklist.io/rules/css/css-at-property

Register CSS custom properties with @property for animation and type safety

CSS custom properties are powerful but limited by default: they are untyped string substitutions that the browser cannot interpolate during transitions or animations. Registering a property with @property gives the browser the information it needs to animate between values, validate token assignments, and scope inheritance — turning custom properties from string macros into first-class typed values. This unlocks gradient animations, typed design tokens, and scoped component theming that are impossible with unregistered properties.

Quick Reference

  • Unregistered custom properties cannot be animated — they transition as discrete strings
  • @property specifies syntax (color, length, number), initial-value, and inherits
  • Registered properties enable smooth interpolation for gradients and complex values
  • inherits: false creates scoped tokens that do not cascade to children

Check

Review the CSS custom properties in this file. Identify any properties that are used in transitions or animations — these require @property registration to animate correctly.

Fix

Add @property registrations for the custom properties used in transitions or animations in this CSS. Include the correct syntax descriptor, an initial-value, and the appropriate inherits value.

Explain

Explain how @property works, why unregistered custom properties cannot be animated, what the syntax descriptor values mean, and how inherits controls cascade behaviour.

Code Review

Inspect all CSS transitions and animations that reference custom properties. Flag any custom property used in a transition or animation that is not registered with @property, and flag any @property registration that is missing initial-value.

For full implementation details, code examples, and framework-specific guidance, see references/rule.md.

Rule page: https://frontendchecklist.io/rules/css/css-at-property

© thedaviddias, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

SKILL.md and 1 other file (references) in skills/css-at-property of thedaviddias/Front-End-Checklist.

  • SKILL.md
  • references/rule.md

Open the folder on GitHubat commit e8d14d0

Compare with similar skills

CSS At Property 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 At Property compared with similar skills
SkillStarsUsed inTokensAuto-checkLicenceRepo updated
CSS At Property this skillthedaviddias/Front-End-Checklist74k—~602Automated safety check: PassMIT
Figma Design System Builderwarpdotdev/warp65k2 repos~4.4kAutomated safety check: PassAGPL-3.0
Figma use_figma Plugin API Ruleswarpdotdev/warp65k4 repos~4.4kAutomated safety check: PassAGPL-3.0
MCP Developmentcoollabsio/coolify63k1 repos~949Automated safety check: PassMIT
Design SystemOhh-889/skyroc79511 repos~1.7kAutomated safety check: PassMIT
Design Dnazanwei/design-dna1.9k1 repos~2.1kAutomated safety check: PassMIT

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Categories

Questions about CSS At Property

What does CSS At Property do?

A skill your agent uses when implementing animated gradients, complex CSS transitions that involve custom property values, or building a typed design token system where custom property misuse should…. CSS At Property is an agent skill from thedaviddias/Front-End-Checklist. Use when implementing animated gradients, complex CSS transitions that involve custom property values, or building a typed design token system where custom property misuse should produce visible errors.

When should I use CSS At Property?

CSS At Property fits situations like: implementing animated gradients; complex CSS transitions that involve custom property values; building a typed design token system where custom property misuse should produce visible errors.

How do I install CSS At Property in Claude Code?

Run `npx skills add thedaviddias/Front-End-Checklist --skill css-at-property -a claude-code`. Or copy the skill folder (skills/css-at-property in thedaviddias/Front-End-Checklist) into .claude/skills/css-at-property in your project. Claude Code loads it when a task matches its description.

How do I install CSS At Property in Codex?

Run `npx skills add thedaviddias/Front-End-Checklist --skill css-at-property -a codex`. Or copy the skill folder (skills/css-at-property in thedaviddias/Front-End-Checklist) into .agents/skills/css-at-property in your project. Codex loads it when a task matches its description.

Can I use CSS At Property 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 thedaviddias/Front-End-Checklist --skill css-at-property -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-at-property, .gemini/skills/css-at-property, .github/skills/css-at-property and .opencode/skills/css-at-property in your project.

What does CSS At Property need to run?

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

Does CSS At Property access the network?

SKILL.md names 1 domain. As links in the text: frontendchecklist.io. This is read from the text; nothing was executed.

Is CSS At Property 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 At Property use?

CSS At Property 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 CSS At Property use?

About 602 tokens (SKILL.md is roughly 2.4k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full. Its references folder adds about 1.7k tokens, read only when the agent opens those files.

What are the alternatives to CSS At Property?

Skills that share tags, products or a category with CSS At Property: Figma Design System Builder (warpdotdev/warp, 65k stars), Figma use_figma Plugin API Rules (warpdotdev/warp, 65k stars), MCP Development (coollabsio/coolify, 63k stars) and Design System (Ohh-889/skyroc, 795 stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains CSS At Property?

thedaviddias (a GitHub user) maintains it in thedaviddias/Front-End-Checklist, which has 74,421 GitHub stars. The repository holds 390 skills in this directory. The repository was last updated on October 6, 2026.

Source: thedaviddias/Front-End-Checklist on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.