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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>
123 lines
4.8 KiB
Markdown
123 lines
4.8 KiB
Markdown
---
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id: css-add-external
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title: "CSS Add External"
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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: ["external CSS", "external style sheet", "link stylesheet", "mystyle.css", "how to add CSS"]
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duplicate_of: ""
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source_trust_level: "B"
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confidence_score: 0.9
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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", "stylesheet"]
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raw_sources: ["https://www.w3schools.com/css/css_howto.asp"]
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applied_in: []
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github_commit: ""
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---
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# [[CSS Add External]]
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## 🎯 한 줄 통찰 (One-line insight)
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There are three ways to insert CSS — external, internal, and inline; an external style sheet lets you change the look of an entire website by editing just one `.css` file, referenced from each page via a `<link>` element in the head. [S1]
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## 🧠 핵심 개념 (Core concepts)
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- **Three ways to insert CSS** — External CSS (link to an external `.css` file), Internal CSS (use the `<style>` element in the head section), and Inline CSS (use the `style` attribute on HTML elements). [S1]
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- **External CSS power** — with an external style sheet, you can change the look of an entire website by changing just one file. [S1]
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- **Reference mechanism** — each HTML page must include a reference to the external style sheet file inside the `<link>` element, inside the head section. [S1]
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- **No space before units** — do not add a space between the property value and the unit (e.g. `20px`, not `20 px`). [S1]
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## 🧩 추출된 패턴 (Extracted patterns)
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- **Single source of truth** — one external `.css` file linked from many pages centralizes site-wide styling. [S1]
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- **Head linkage** — `<link rel="stylesheet" href="…css">` inside `<head>` connects a page to its stylesheet. [S1]
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## 📖 세부 내용 (Details)
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CSS can be added to HTML documents in 3 ways: [S1]
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1. **External CSS** — link to an external `.css` file.
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2. **Internal CSS** — use the `<style>` element in the head section.
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3. **Inline CSS** — use the `style` attribute on HTML elements.
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**External CSS** — with an external style sheet, you can change the look of an entire website by changing just one file! Each HTML page must include a reference to the external style sheet file inside the `<link>` element, inside the head section. [S1]
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```html
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<!DOCTYPE html>
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<html>
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<head>
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<link rel="stylesheet" href="mystyle.css">
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</head>
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<body>
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<h1>This is a heading</h1>
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<p>This is a paragraph.</p>
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</body>
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</html>
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```
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An external style sheet can be written in any text editor and must be saved with a `.css` extension. The external `.css` file (`mystyle.css`) should not contain any HTML tags — it holds only style rules: [S1]
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```css
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body {
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background-color: lightblue;
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}
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h1 {
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color: navy;
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margin-left: 20px;
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}
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```
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**Note:** Do not add a space between the property value and the unit. [S1]
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- Incorrect (space): `margin-left: 20 px;`
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- Correct (no space): `margin-left: 20px;`
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## 🛠️ 적용 사례 (Applied in summary)
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The page's own example links an HTML page to `mystyle.css`, which styles `body` and `h1`. No external project/commit applications found in the source.
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## 💻 코드 패턴 (Code patterns)
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Linking an external stylesheet from the head (language: HTML):
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```html
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<head>
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<link rel="stylesheet" href="mystyle.css">
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</head>
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```
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The external stylesheet file (language: CSS):
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```css
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body {
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background-color: lightblue;
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}
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h1 {
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color: navy;
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margin-left: 20px;
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}
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```
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## ⚖️ 비교 및 선택 기준 (Comparison & decision criteria)
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| Method | How it is added | Best use |
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| --- | --- | --- |
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| External CSS | `<link>` to a `.css` file in `<head>` | Change an entire website's look by editing one file [S1] |
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| Internal CSS | `<style>` element in the head section | A single HTML page with a unique style [S1] |
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| Inline CSS | `style` attribute on an HTML element | A unique style for a single element [S1] |
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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:** 0.9
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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 Add Internal]], [[CSS Add Inline]], [[CSS Multiple Style Sheets]]
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- **참조 맥락:** Referenced when connecting an HTML page to a centralized, site-wide stylesheet.
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## 📚 출처 (Sources)
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- [S1] W3Schools — CSS Add External — https://www.w3schools.com/css/css_howto.asp
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## 📝 변경 이력 (Change history)
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- 2026-06-23: Initial draft synthesized from the W3Schools "CSS Add External" page (Astra wiki-curation, P-Reinforce v3.1 format).
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