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-background-shorthand
+title: "CSS Background Shorthand"
+category: "Frontend"
+status: "draft"
+verification_status: "conceptual"
+canonical_id: ""
+aliases: ["background shorthand", "background property", "CSS background shorthand", "shorthand background", "background: shorthand"]
+duplicate_of: ""
+source_trust_level: "B"
+confidence_score: 0.88
+created_at: 2026-06-23
+updated_at: 2026-06-23
+review_reason: ""
+merge_history: []
+tags: ["css", "web", "frontend", "w3schools", "background", "shorthand"]
+raw_sources: ["https://www.w3schools.com/css/css_background_shorthand.asp"]
+applied_in: []
+github_commit: ""
+---
+
+# [[CSS Background Shorthand]]
+
+## 🎯 한 줄 통찰 (One-line insight)
+To shorten the code, the `background` shorthand property lets you specify all the background properties in one single declaration. [S1]
+
+## 🧠 핵심 개념 (Core concepts)
+- **background shorthand** — to shorten the code, it is possible to specify all the background properties in one single property. [S1]
+- **Replaces longhand** — a single `background:` declaration can replace separate `background-color`, `background-image`, `background-repeat`, and `background-position` declarations. [S1]
+- **Constituent properties** — the page lists the individual properties the shorthand can combine: `background-attachment`, `background-clip`, `background-color`, `background-image`, `background-origin`, `background-position`, `background-repeat`, and `background-size`. [S1]
+- **Omitted values** — if some property values are missing, they will be set to their initial (default) values. [S1]
+
+## 🧩 추출된 패턴 (Extracted patterns)
+- **Collapse the longhand** — replace a block of `background-*` declarations with one `background:` line for brevity. [S1]
+- **Rely on defaults** — only list the values you need; omitted ones fall back to their initial values. [S1]
+
+## 📖 세부 내용 (Details)
+**Background - Shorthand property**
+To shorten the code, it is also possible to specify all the background properties in one single property. This is called a shorthand property. [S1]
+
+Instead of writing the properties separately: [S1]
+```css
+body {
+  background-color: #ffffff;
+  background-image: url("img_tree.png");
+  background-repeat: no-repeat;
+  background-position: right top;
+}
+```
+
+You can use the shorthand `background` property: [S1]
+```css
+body {
+  background: #ffffff url("img_tree.png") no-repeat right top;
+}
+```
+
+The shorthand `background` property can combine the following individual background properties: [S1]
+- `background-attachment`
+- `background-clip`
+- `background-color`
+- `background-image`
+- `background-origin`
+- `background-position`
+- `background-repeat`
+- `background-size`
+
+If some of the property values are missing, they will be set to their initial (default) values. [S1]
+
+**Order of values:** The page does not explicitly prescribe a required ordering of the values; the example writes them as color, image, repeat, then position (`#ffffff url("img_tree.png") no-repeat right top`). An explicit ordering rule was: Not found in source. [S1]
+
+## 🛠️ 적용 사례 (Applied in summary)
+The longhand and shorthand `body` rules above are the page's own demonstration examples. No external project/commit applications found in the source.
+
+## 💻 코드 패턴 (Code patterns)
+Background shorthand (language: CSS):
+```css
+selector {
+  background: #ffffff url("img_tree.png") no-repeat right top;
+}
+```
+
+## ⚖️ 비교 및 선택 기준 (Comparison & decision criteria)
+- **Longhand vs shorthand** — separate `background-*` declarations are explicit and easy to read property by property; the `background` shorthand is more compact and sets any unspecified values to their initial defaults. Choose the shorthand to shorten the code. [S1]
+
+## ⚖️ 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:** 0.88
+- **중복 검사 결과:** 신규 생성 (New discovery)
+
+## 🔗 지식 그래프 (Knowledge Graph)
+- **상위/루트:** [[CSS Tutorial]]
+- **관련 개념:** [[CSS Background Color]], [[CSS Background Image]], [[CSS Background Repeat]], [[CSS Background Attachment]]
+- **참조 맥락:** Referenced when collapsing multiple background-* declarations into one concise rule.
+
+## 📚 출처 (Sources)
+- [S1] W3Schools — CSS Background Shorthand — https://www.w3schools.com/css/css_background_shorthand.asp
+
+## 📝 변경 이력 (Change history)
+- 2026-06-23: Initial draft synthesized from the W3Schools "CSS Background Shorthand" page (Astra wiki-curation, P-Reinforce v3.1 format).