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-multiple-backgrounds
+title: "CSS Multiple Backgrounds"
+category: "Frontend"
+status: "draft"
+verification_status: "conceptual"
+canonical_id: ""
+aliases: ["multiple backgrounds", "background-image list", "stacked backgrounds", "CSS3 backgrounds", "comma-separated backgrounds", "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", "background-image"]
+raw_sources: ["https://www.w3schools.com/css/css3_backgrounds.asp"]
+applied_in: []
+github_commit: ""
+---
+
+# [[CSS Multiple Backgrounds]]
+
+## 🎯 한 줄 통찰 (One-line insight)
+CSS allows multiple background images on a single element via a comma-separated list on `background-image`, with the images stacked so the first one listed sits closest to the viewer. [S1]
+
+## 🧠 핵심 개념 (Core concepts)
+- **Multiple images** — CSS allows you to add multiple background images for an element through the `background-image` property. [S1]
+- **Comma separation** — the different background images are separated by commas. [S1]
+- **Stacking order** — the images are stacked on top of each other, where the first image is closest to the viewer. [S1]
+- **Shorthand** — the `background` shorthand can declare each image's position and repeat behavior in a single property. [S1]
+
+## 🧩 추출된 패턴 (Extracted patterns)
+- **Parallel-list pattern** — `background-image`, `background-position`, and `background-repeat` each take a comma-separated list whose items correspond positionally to each image. [S1]
+- **Shorthand-collapse pattern** — the same multi-image setup can be collapsed into one `background` declaration per image, comma-separated. [S1]
+
+## 📖 세부 내용 (Details)
+**CSS Multiple Backgrounds**
+CSS allows you to add multiple background images for an element, through the `background-image` property. The different background images are separated by commas, and the images are stacked on top of each other, where the first image is closest to the viewer. [S1]
+
+The tutorial demonstrates this with two images: a flower aligned to the bottom-right and a paper-like background at the top-left. [S1]
+
+Example — using the individual background properties: [S1]
+```css
+#example1 {
+  background-image: url(img_flwr.gif), url(paper.gif);
+  background-position: right bottom, left top;
+  background-repeat: no-repeat, repeat;
+}
+```
+
+Example — using the `background` shorthand property: [S1]
+```css
+#example1 {
+  background: url(img_flwr.gif) right bottom no-repeat, url(paper.gif) left top repeat;
+}
+```
+
+Multiple background images can be specified using either the individual background properties (as above) or the `background` shorthand property. [S1]
+
+**CSS Advanced Background Properties**
+
+| Property | Description |
+|----------|-------------|
+| `background` | A shorthand property for setting all the background properties in one declaration |
+| `background-clip` | Specifies the painting area of the background |
+| `background-image` | Specifies one or more background images for an element |
+| `background-origin` | Specifies where the background image(s) is/are positioned |
+| `background-size` | Specifies the size of the background image(s) |
+
+[S1]
+
+## ⚖️ 비교 및 선택 기준 (Comparison & decision criteria)
+The same multi-image background can be written two ways: [S1]
+- **Individual properties** (`background-image` + `background-position` + `background-repeat` lists) — more explicit and readable when each image needs distinct position/repeat values that you want to scan separately.
+- **`background` shorthand** — more compact, grouping each image's URL, position, and repeat into one comma-separated entry.
+Both produce the same result; the choice is about verbosity vs. compactness. [S1]
+
+## 🛠️ 적용 사례 (Applied in summary)
+The page's `#example1` (flower bottom-right over a repeating paper background, shown via both the longhand and shorthand forms) is the applied case. No external project/commit applications found in the source.
+
+## 💻 코드 패턴 (Code patterns)
+Two stacked backgrounds via individual properties (language: CSS):
+```css
+selector {
+  background-image: url(img_flwr.gif), url(paper.gif);
+  background-position: right bottom, left top;
+  background-repeat: no-repeat, repeat;
+}
+```
+Same result via shorthand:
+```css
+selector {
+  background: url(img_flwr.gif) right bottom no-repeat, url(paper.gif) left top repeat;
+}
+```
+
+## ⚖️ 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 Size]], [[CSS Background Origin]], [[CSS Background Clip]]
+- **참조 맥락:** Referenced when layering textures, overlays, or decorative images behind content in a single element.
+
+## 📚 출처 (Sources)
+- [S1] W3Schools — CSS Multiple Backgrounds — https://www.w3schools.com/css/css3_backgrounds.asp
+
+## 📝 변경 이력 (Change history)
+- 2026-06-23: Initial draft synthesized from the W3Schools "CSS Multiple Backgrounds" page (Astra wiki-curation, P-Reinforce v3.1 format).