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>

10_Wiki/Topic_CSS/CSS_Overflow_XY.md

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+---
+id: css-overflow-x-and-y
+title: "CSS Overflow X and Y"
+category: "Frontend"
+status: "draft"
+verification_status: "conceptual"
+canonical_id: ""
+aliases: ["overflow-x", "overflow-y", "CSS overflow xy", "horizontal overflow", "vertical overflow", "directional overflow"]
+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", "overflow", "layout"]
+raw_sources: ["https://www.w3schools.com/css/css_overflow_xy.asp"]
+applied_in: []
+github_commit: ""
+---
+
+# [[CSS Overflow X and Y]]
+
+## 🎯 한 줄 통찰 (One-line insight)
+`overflow-x` and `overflow-y` control overflow independently per axis — the horizontal (left/right) edges and the vertical (top/bottom) edges — giving finer control than the single `overflow` shorthand. [S1]
+
+## 🧠 핵심 개념 (Core concepts)
+- **overflow-x** — specifies what to do with the left/right edges of the content. [S1]
+- **overflow-y** — specifies what to do with the top/bottom edges of the content. [S1]
+- **independent control** — the two properties allow managing layout more precisely than using the general `overflow` property alone. [S1]
+
+## 🧩 추출된 패턴 (Extracted patterns)
+- **Asymmetric scrolling** — combine different values per axis (e.g. `overflow-x: hidden; overflow-y: scroll;`) when horizontal and vertical content should behave differently. [S1]
+- **Single-axis scroll regions** — wide tables and code blocks use `overflow-x: auto`; chat feeds use `overflow-y: scroll`. [S1]
+
+## 📖 세부 내용 (Details)
+**Core concepts** [S1]
+`overflow-x` and `overflow-y` control how content overflows independently in each direction. `overflow-x` specifies what to do with the left/right edges of the content; `overflow-y` specifies what to do with the top/bottom edges of the content. These allow developers to manage layout more precisely than using the general `overflow` property alone.
+
+**Example 1 — hide horizontal, add vertical scrollbar** [S1]
+```css
+div {
+  overflow-x: hidden;
+  overflow-y: scroll;
+}
+```
+
+**Example 2 — horizontal scrollbar only** [S1]
+```css
+div {
+  overflow-x: scroll;
+  overflow-y: hidden;
+}
+```
+
+**Common use cases** [S1]
+1. **Horizontal scrolling table** — use `overflow-x: auto` for wide data tables.
+2. **Chat windows** — use `overflow-y: scroll` for vertical message feeds.
+3. **Code blocks** — use `overflow-x: auto` to accommodate lengthy code lines.
+
+These directional properties provide granular control when different scroll behavior is needed for horizontal versus vertical content overflow.
+
+## 🛠️ 적용 사례 (Applied in summary)
+The page applies the properties to a `div`: hiding horizontal overflow while scrolling vertically, and scrolling horizontally while hiding vertical overflow. Listed real-world uses are horizontally scrolling tables, vertically scrolling chat windows, and horizontally scrolling code blocks. No external project/commit applications found in the source.
+
+## 💻 코드 패턴 (Code patterns)
+Vertical scroll, no horizontal overflow (language: CSS):
+```css
+div {
+  overflow-x: hidden;
+  overflow-y: scroll;
+}
+```
+
+Horizontal scroll, no vertical overflow (language: CSS):
+```css
+div {
+  overflow-x: scroll;
+  overflow-y: hidden;
+}
+```
+
+## ⚖️ 비교 및 선택 기준 (Comparison & decision criteria)
+- **overflow (shorthand)** — applies the same behavior to both axes. [S1]
+- **overflow-x / overflow-y** — set behavior per axis independently; choose these when horizontal and vertical content should scroll or clip differently (e.g. wide tables, chat feeds, code blocks). [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:** 0.87
+- **중복 검사 결과:** 신규 생성 (New discovery)
+
+## 🔗 지식 그래프 (Knowledge Graph)
+- **상위/루트:** [[CSS Tutorial]]
+- **관련 개념:** [[CSS Overflow]], [[CSS Position Fixed and Absolute]], [[CSS Float]]
+- **참조 맥락:** Referenced when a container needs different overflow behavior on the horizontal versus the vertical axis.
+
+## 📚 출처 (Sources)
+- [S1] W3Schools — CSS Overflow X and Y — https://www.w3schools.com/css/css_overflow_xy.asp
+
+## 📝 변경 이력 (Change history)
+- 2026-06-23: Initial draft synthesized from the W3Schools "CSS Overflow X and Y" page (Astra wiki-curation, P-Reinforce v3.1 format).