2nd/10_Wiki/Topic_Programming/Topic_CSS/CSS_Property_Rule.md

id, title, category, status, verification_status, canonical_id, aliases, duplicate_of, source_trust_level, confidence_score, created_at, updated_at, review_reason, merge_history, tags, raw_sources, applied_in, github_commit

id	title	category	status	verification_status	canonical_id	aliases	duplicate_of	source_trust_level	confidence_score	created_at	updated_at	review_reason	merge_history	tags	raw_sources	applied_in	github_commit
css-property	CSS @property	Frontend	draft	conceptual		@property rule CSS at-property typed custom properties registered custom properties CSS property syntax inherits initial-value		B	0.87	2026-06-23	2026-06-23			css web frontend w3schools css-variables at-rules animation	https://www.w3schools.com/css/css3_property.asp

CSS @property

🎯 한 줄 통찰 (One-line insight)

@property defines custom CSS properties (CSS variables) directly in the stylesheet — without JavaScript — adding data-type checking, a required default value, and explicit control over inheritance. [S1]

🧠 핵심 개념 (Core concepts)

• What it is — @property is used to define custom CSS properties (CSS variables) directly in the stylesheet without having to run any JavaScript. [S1]
• Data type checking — ensures custom properties are used correctly via a declared syntax (e.g. "<color>"). [S1]
• Default value requirement — initial-value provides a fallback if an invalid value is assigned. [S1]
• Inheritance control — inherits: true | false gives full control over whether the value inherits. [S1]
• Consumed with var() — once defined, the property is used like any custom property, e.g. background-color: var(--myColor);. [S1]

🧩 추출된 패턴 (Extracted patterns)

• Typed declaration pattern — @property --name { syntax: "<type>"; inherits: <bool>; initial-value: <value>; }. [S1]
• Invalid-value fallback — when a value violates the declared syntax (e.g. assigning 2 where a <color> is expected), the property falls back to its initial-value instead of breaking. [S1]
• Animatable custom colors — declaring color custom properties with @property enables them to participate in transitions/animations (e.g. a gradient that animates between --startColor and --endColor). [S1]

📖 세부 내용 (Details)

@property is used to define custom CSS properties (CSS variables) directly in the stylesheet without having to run any JavaScript, with data type checking, default values, and inheritance control. [S1]

Basic syntax [S1]

@property --myColor {
  syntax: "<color>";
  inherits: true;
  initial-value: lightgray;
}

Usage with the var() function: [S1]

body {
  background-color: var(--myColor);
}

Example 1 — two custom properties [S1]

@property --my-bg-color {
  syntax: "<color>";
  inherits: true;
  initial-value: lightgray;
}

@property --my-txt-color {
  syntax: "<color>";
  inherits: true;
  initial-value: darkblue;
}

div {
  width: 300px;
  height: 150px;
  padding: 15px;
  background-color: var(--my-bg-color);
  color: var(--my-txt-color);
}

Example 2 — overriding custom properties per class [S1]

@property --my-bg-color {
  syntax: "<color>";
  inherits: true;
  initial-value: lightgray;
}

div {
  width: 300px;
  height: 150px;
  padding: 15px;
  background-color: var(--my-bg-color);
}

.fresh {
  --my-bg-color: #ff6347;
}

.nature {
  --my-bg-color: rgb(120, 180, 30);
}

Example 3 — type checking with an invalid value [S1] Here .nature assigns 2, which is not a valid <color>, so the property falls back to its initial-value: [S1]

@property --my-bg-color {
  syntax: "<color>";
  inherits: true;
  initial-value: lightgray;
}

div {
  width: 300px;
  height: 150px;
  padding: 15px;
  background-color: var(--my-bg-color);
}

.fresh {
  --my-bg-color: #ff6347;
}

.nature {
  --my-bg-color: 2;
}

Example 4 — inherits: false [S1]

@property --my-bg-color {
  syntax: "<color>";
  inherits: false;
  initial-value: lightgray;
}

Example 5 — inherits: true [S1]

@property --my-bg-color {
  syntax: "<color>";
  inherits: true;
  initial-value: lightgray;
}

Example 6 — animated gradient colors [S1]

@property --startColor {
  syntax: "<color>";
  initial-value: #EADEDB;
  inherits: false;
}

@property --endColor {
  syntax: "<color>";
  initial-value: #BC70A4;
  inherits: false;
}

Key benefits listed by the source [S1]

• Data type checking ensures custom properties are used correctly.
• Default value requirement provides a fallback if invalid values are assigned.
• Inheritance control gives full control over value inheritance behavior.

🛠️ 적용 사례 (Applied in summary)

The page's applied examples progress from declaring typed color properties (Example 1), overriding them per class .fresh / .nature (Example 2), demonstrating fallback to initial-value on an invalid 2 (Example 3), contrasting inherits: false vs inherits: true (Examples 4–5), and finally declaring --startColor/--endColor for an animated gradient (Example 6). No external project/commit applications found in the source.

💻 코드 패턴 (Code patterns)

Define a typed custom property (language: CSS):

@property --my-bg-color {
  syntax: "<color>";
  inherits: true;
  initial-value: lightgray;
}

Consume it (language: CSS):

div {
  background-color: var(--my-bg-color);
}

⚖️ 모순 및 업데이트 (Contradictions & updates)

No contradictions found in the source.

✅ 검증 상태 및 신뢰도

• 상태: draft
• 검증 단계: conceptual (실제 적용 사례 발견 시 applied/validated로 승격 가능)
• 출처 신뢰도: B (W3Schools — widely used educational reference, not a primary standards body)
• 신뢰 점수: 0.87
• 중복 검사 결과: 신규 생성 (New discovery)

🔗 지식 그래프 (Knowledge Graph)

• 상위/루트: CSS Tutorial
• 관련 개념: CSS Variables, CSS Variables and JavaScript, CSS Variables in Media Queries, CSS var Function
• 참조 맥락: Referenced when custom properties need type safety, guaranteed fallbacks, or animation support without JavaScript.

📚 출처 (Sources)

• [S1] W3Schools — CSS @property — https://www.w3schools.com/css/css3_property.asp

📝 변경 이력 (Change history)

• 2026-06-23: Initial draft synthesized from the W3Schools "CSS @property" page (Astra wiki-curation, P-Reinforce v3.1 format).