2nd/10_Wiki/Topic_CSS/CSS_Specificity_Hierarchy.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-specificity-hierarchy	CSS Specificity Hierarchy	Frontend	draft	conceptual		specificity hierarchy specificity weight specificity X-Y-Z selector ranking specificity calculation		B	0.86	2026-06-23	2026-06-23			css web frontend w3schools specificity selectors cascade	https://www.w3schools.com/css/css_specificity_hierarchy.asp

CSS Specificity Hierarchy

🎯 한 줄 통찰 (One-line insight)

Every selector earns a three-number weight (X-Y-Z) counting ID, class/attribute/pseudo-class, and element/pseudo-element selectors — the higher leftmost number wins, deciding which rule applies. [S1]

🧠 핵심 개념 (Core concepts)

• Four ranked categories — from highest to lowest the hierarchy is: inline styles, ID selectors, classes/attributes/pseudo-classes, and elements/pseudo-elements. [S1]
• Three-digit weight notation (X-Y-Z) — X counts ID selectors, Y counts class, attribute, and pseudo-class selectors, and Z counts element and pseudo-element selectors. [S1]
• Leftmost-number-wins comparison — the selector with the higher leftmost number wins; if those are equal, compare the next number, and so on. [S1]
• Universal selector contributes nothing — the universal selector (*) and :where() add no specificity weight. [S1]

🧩 추출된 패턴 (Extracted patterns)

• Count-then-compare pattern — to resolve a conflict, count each selector's ID/class/element selectors into X-Y-Z, then compare position by position from the left. [S1]
• Compound selectors stack weight — combining selector types (e.g. p#demo) adds their individual weights together (1-0-0 + 0-0-1 = 1-0-1). [S1]

📖 세부 내용 (Details)

Hierarchy of selector categories. Specificity ranks selector types as follows (highest priority first) [S1]:

Rank (high → low)	Selector category
1 (highest)	Inline styles
2	ID selectors
3	Classes, attributes, and pseudo-classes
4	Elements and pseudo-elements
5 (lowest)	Universal selector and :where()

Weight notation (X-Y-Z). Specificity is written as a three-number value where [S1]:

• X = the count of ID selectors,
• Y = the count of class selectors, attribute selectors, and pseudo-classes,
• Z = the count of element selectors and pseudo-elements.

The selector with the higher leftmost number wins; if equal, the next number is compared, and so on. [S1]

Example — competing selectors with computed weights. The page demonstrates the weights of several selectors targeting the same element. The compound selector p#demo (weight 1-0-1) beats the bare #demo (weight 1-0-0) because, with the ID counts tied at 1, its element count breaks the tie. [S1]

#demo {color: blue;} /* weight: 1-0-0 */
p#demo {color: orange;} /* weight: 1-0-1 WINS! */
.test {color: green;} /* weight: 0-1-0 */
p.test {color: green;} /* weight: 0-1-1 */
p {color: red;} /* weight: 0-0-1 */

Tie-breaking rules noted on the page. When specificity is equal, later rules win; ID selectors beat attribute selectors; and class selectors beat element selectors. [S1]

🛠️ 적용 사례 (Applied in summary)

The weight-annotated example above is the page's applied demonstration: each selector is labeled with its X-Y-Z weight so the reader can see exactly why p#demo (1-0-1) wins over the others. No external project/commit applications found in the source.

💻 코드 패턴 (Code patterns)

Annotating selectors with their specificity weight (language: CSS):

#demo {color: blue;}     /* 1-0-0 */
p#demo {color: orange;}  /* 1-0-1  — wins: ID tied, element breaks the tie */
.test {color: green;}    /* 0-1-0 */
p {color: red;}          /* 0-0-1 */

⚖️ 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: 0.86
• 중복 검사 결과: 신규 생성 (New discovery)

🔗 지식 그래프 (Knowledge Graph)

• 상위/루트: CSS Tutorial
• 관련 개념: CSS Specificity, CSS !important, CSS Selectors
• 참조 맥락: Used to compute and compare selector weights when diagnosing why a particular CSS rule does or does not apply.

📚 출처 (Sources)

• [S1] W3Schools — CSS Specificity Hierarchy — https://www.w3schools.com/css/css_specificity_hierarchy.asp

📝 변경 이력 (Change history)

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