docs(10_Wiki): W3Schools 위키화 — HTML/CSS/JavaScript(core)

W3Schools 튜토리얼을 P-Reinforce v3.1 포맷으로 위키화(영어 본문, 한/영 섹션 헤더). - Topic_HTML: 59문서 (튜토리얼+예제, 레퍼런스/메타 제외) - Topic_CSS: 190문서 (메인 + Advanced/Flexbox/Grid/RWD 전체) - Topic_JavaScript: 120문서 (코어 언어; Temporal/DOM상세/BOM/WebAPI/AJAX/jQuery/Graphics 등은 후속) 각 폴더 00_INDEX.md(MOC) 포함. 코드 verbatim, 미확인분은 "Not found in source" 표기. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
2026-06-23 19:21:18 +09:00
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+---
+id: css-important
+title: "CSS !important"
+category: "Frontend"
+status: "draft"
+verification_status: "conceptual"
+canonical_id: ""
+aliases: ["!important", "important rule", "CSS override priority", "important declaration", "highest priority CSS"]
+duplicate_of: ""
+source_trust_level: "B"
+confidence_score: 0.87
+created_at: 2026-06-23
+updated_at: 2026-06-23
+review_reason: ""
+merge_history: []
+tags: ["css", "web", "frontend", "w3schools", "important", "cascade", "specificity"]
+raw_sources: ["https://www.w3schools.com/css/css_important.asp"]
+applied_in: []
+github_commit: ""
+---
+
+# [[CSS !important]]
+
+## 🎯 한 줄 통찰 (One-line insight)
+The `!important` rule forces a CSS property value to the highest priority, overriding every other styling rule for that property on an element — powerful, but to be used sparingly. [S1]
+
+## 🧠 핵심 개념 (Core concepts)
+- **Highest priority** — `!important` assigns the highest priority to a CSS property value, overriding all previous styling rules for that specific property on an element. [S1]
+- **Overrides specificity** — an `!important` declaration beats inline styles, ID selectors, and class selectors even though those would normally have higher specificity. [S1]
+- **Use sparingly** — overusing `!important` creates confusing, difficult-to-debug CSS code. [S1]
+
+## 🧩 추출된 패턴 (Extracted patterns)
+- **Property-level override pattern** — append `!important` to a single declaration (`property: value !important;`) to lock that one property's value. [S1]
+- **Accessibility escape hatch** — pairing `!important` with a `prefers-reduced-motion` media query guarantees motion is suppressed for users who request it. [S1]
+
+## 📖 세부 내용 (Details)
+**What `!important` does.** The `!important` rule assigns the highest priority to a CSS property value, overriding all previous styling rules for that specific property on an element. [S1]
+
+**Syntax.** [S1]
+```css
+selector {
+  property: value !important;
+}
+```
+
+**Example — basic override.** When `background-color: yellow !important;` is applied to paragraphs, all the paragraphs display a yellow background regardless of inline styles, ID selectors, or class selectors that would otherwise have higher specificity. [S1]
+```css
+p {
+  background-color: yellow !important;
+}
+```
+
+**Example — accessibility / reduced motion.** `!important` is used to respect a user's motion-sensitivity preference, forcing animations and transitions off for everyone who requests reduced motion. [S1]
+```css
+@media (prefers-reduced-motion: reduce) {
+  * {
+    animation: none !important;
+    transition: none !important;
+  }
+}
+```
+
+**Other examples on the page.** The page also shows competing/multiple `!important` declarations across different selectors (illustrating how this can create confusing CSS) and a link-button styling case where `!important` enforces consistent styling across conflicting selectors. The exact additional source code for these boxes was not captured verbatim from the source. [S1] (Not found in source — verbatim code.)
+
+**Fair use cases.** The page lists legitimate reasons to use `!important` [S1]:
+1. Overriding styles in a Content Management System (CMS) where the CSS cannot be edited directly.
+2. Respecting user accessibility preferences (such as reduced motion).
+3. Creating unchangeable styles for specific elements.
+
+**Warning.** Use `!important` sparingly — excessive use creates confusing, difficult-to-debug CSS code. [S1]
+
+## 🛠️ 적용 사례 (Applied in summary)
+The page's applied demonstrations include forcing a yellow paragraph background over higher-specificity rules, and the `prefers-reduced-motion` accessibility block that kills animations and transitions. No external project/commit applications found in the source.
+
+## 💻 코드 패턴 (Code patterns)
+Locking a single property (language: CSS):
+```css
+selector {
+  property: value !important;
+}
+```
+Accessibility-driven blanket override (language: CSS):
+```css
+@media (prefers-reduced-motion: reduce) {
+  * {
+    animation: none !important;
+    transition: none !important;
+  }
+}
+```
+
+## ⚖️ 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 Specificity]], [[CSS Specificity Hierarchy]], [[CSS Accessibility]]
+- **참조 맥락:** Reached for when a style must override everything else, or when ruling out an `!important` rule as the cause of an un-overridable style.
+
+## 📚 출처 (Sources)
+- [S1] W3Schools — CSS !important — https://www.w3schools.com/css/css_important.asp
+
+## 📝 변경 이력 (Change history)
+- 2026-06-23: Initial draft synthesized from the W3Schools "CSS !important" page (Astra wiki-curation, P-Reinforce v3.1 format).