How do I install the CSS At Property skill?

Run npx skillmds@latest add thedaviddias/css-at-property in your terminal (requires Node.js), paste this page's agent-chat prompt into Claude, Cursor, or any MCP-connected agent, or download the SKILL.md file and copy it into your agent's skills directory.

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Is CSS At Property free to use?

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Who published CSS At Property?

thedaviddias (@thedaviddias) published this skill. Their other Agent Skills are listed on their SkillMD profile.

CSS At Property by thedaviddias — Agent Skill

Name: CSS At Property
Author: thedaviddias

CSS At Property

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.

thedaviddias 2074b2d 2 files · 8.8 KB Updated Sep 17, 2026

File contents

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/en/rules/css/css-at-property

---name: css-at-propertydescription: 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.---# Register CSS custom properties with @property for animation and type safetyCSS 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## CheckReview the CSS custom properties in this file. Identify any properties that are used in transitions or animations — these require @property registration to animate correctly.## FixAdd @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.## ExplainExplain how @property works, why unregistered custom properties cannot be animated, what the syntax descriptor values mean, and how inherits controls cascade behaviour.## Code ReviewInspect 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/en/rules/css/css-at-property

Frequently asked questions