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>
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id: css-background-origin
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title: "CSS Background Origin"
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category: "Frontend"
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status: "draft"
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verification_status: "conceptual"
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canonical_id: ""
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aliases: ["background-origin", "padding-box", "border-box origin", "content-box origin", "background positioning area", "background image start"]
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duplicate_of: ""
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source_trust_level: "B"
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confidence_score: 0.88
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created_at: 2026-06-23
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updated_at: 2026-06-23
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review_reason: ""
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merge_history: []
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tags: ["css", "web", "frontend", "w3schools", "background", "background-origin"]
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raw_sources: ["https://www.w3schools.com/css/css3_background_origin.asp"]
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applied_in: []
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github_commit: ""
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---
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# [[CSS Background Origin]]
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## 🎯 한 줄 통찰 (One-line insight)
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The `background-origin` property specifies where the background image is positioned relative to the box model — starting from the padding edge (default), the border edge, or the content edge. [S1]
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## 🧠 핵심 개념 (Core concepts)
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- **`background-origin`** — specifies where the background image is positioned. [S1]
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- **`padding-box`** — the background image starts from the top-left corner of the padding edge; this is the default. [S1]
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- **`border-box`** — the background image starts from the top-left corner of the border edge. [S1]
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- **`content-box`** — the background image starts from the top-left corner of the content edge. [S1]
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- **Fixed-attachment caveat** — this property has no effect if `background-attachment` is set to `fixed`. [S1]
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## 🧩 추출된 패턴 (Extracted patterns)
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- **Box-model anchor pattern** — the chosen value (`padding-box` / `border-box` / `content-box`) selects which box-model edge the image's top-left corner aligns to. [S1]
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- **Default-vs-inset pattern** — `border-box` lets the image extend out under the border, while `content-box` insets it past the padding. [S1]
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## 📖 세부 내용 (Details)
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**CSS `background-origin` Property**
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The `background-origin` property specifies where the background image is positioned. [S1]
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The property takes three different values: [S1]
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- `padding-box` — the background image starts from the top-left corner of the padding edge. This is default. [S1]
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- `border-box` — the background image starts from the top-left corner of the border edge. [S1]
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- `content-box` — the background image starts from the top-left corner of the content edge. [S1]
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**Note:** This property has no effect if the `background-attachment` property is set to `fixed`. [S1]
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Example — the three origin values across three divs: [S1]
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```css
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#div1 {
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border: 2px solid black;
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padding: 35px;
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background-image: url(img_flwr.gif);
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background-repeat: no-repeat;
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background-origin: padding-box;
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}
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#div2 {
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border: 2px solid black;
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padding: 35px;
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background-image: url(img_flwr.gif);
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background-repeat: no-repeat;
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background-origin: border-box;
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}
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#div3 {
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border: 2px solid black;
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padding: 35px;
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background-image: url(img_flwr.gif);
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background-repeat: no-repeat;
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background-origin: content-box;
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}
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```
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**CSS Background Properties**
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| Property | Description |
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|----------|-------------|
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| `background` | A shorthand property for setting all the background properties in one declaration |
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| `background-clip` | Specifies the painting area of the background |
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| `background-image` | Specifies one or more background images for an element |
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| `background-origin` | Specifies where the background image(s) is/are positioned |
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| `background-size` | Specifies the size of the background image(s) |
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[S1]
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## ⚖️ 비교 및 선택 기준 (Comparison & decision criteria)
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Choosing the origin value relative to the box model: [S1]
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- **`padding-box`** (default) — image's top-left aligns to the padding edge; the usual behavior.
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- **`border-box`** — image starts at the border edge, so it appears under the border.
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- **`content-box`** — image starts at the content edge, inset past both border and padding.
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Note these only affect positioning of the image's origin; with `background-attachment: fixed`, the property has no effect. [S1]
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## 🛠️ 적용 사례 (Applied in summary)
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The page's three-div example (identical flower image with `padding-box`, `border-box`, and `content-box`) is the applied case. No external project/commit applications found in the source.
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## 💻 코드 패턴 (Code patterns)
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Anchor the background image to the content edge (language: CSS):
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```css
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selector {
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border: 2px solid black;
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padding: 35px;
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background-image: url(img_flwr.gif);
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background-repeat: no-repeat;
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background-origin: content-box;
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}
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```
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## ⚖️ 모순 및 업데이트 (Contradictions & updates)
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No contradictions found in the source.
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## ✅ 검증 상태 및 신뢰도
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- **상태:** draft
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- **검증 단계:** conceptual (실제 적용 사례 발견 시 applied/validated로 승격 가능)
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- **출처 신뢰도:** B (W3Schools — widely used educational reference, not a primary standards body)
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- **신뢰 점수:** 0.88
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- **중복 검사 결과:** 신규 생성 (New discovery)
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## 🔗 지식 그래프 (Knowledge Graph)
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- **상위/루트:** [[CSS Tutorial]]
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- **관련 개념:** [[CSS Background Clip]], [[CSS Background Size]], [[CSS Multiple Backgrounds]]
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- **참조 맥락:** Referenced when controlling exactly where a background image begins relative to border and padding.
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## 📚 출처 (Sources)
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- [S1] W3Schools — CSS Background Origin — https://www.w3schools.com/css/css3_background_origin.asp
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## 📝 변경 이력 (Change history)
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- 2026-06-23: Initial draft synthesized from the W3Schools "CSS Background Origin" page (Astra wiki-curation, P-Reinforce v3.1 format).
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