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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>
120 lines
5.0 KiB
Markdown
120 lines
5.0 KiB
Markdown
---
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id: css-rgb-colors
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title: "CSS RGB Colors"
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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: ["RGB", "rgb()", "RGBA", "rgba()", "RGB color model", "CSS RGB values"]
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duplicate_of: ""
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source_trust_level: "B"
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confidence_score: 0.89
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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", "color", "rgb", "rgba"]
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raw_sources: ["https://www.w3schools.com/css/css_colors_rgb.asp"]
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applied_in: []
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github_commit: ""
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---
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# [[CSS RGB Colors]]
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## 🎯 한 줄 통찰 (One-line insight)
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An RGB color value is defined with `rgb(red, green, blue)`, where each light source ranges from 0 to 255, and `rgba()` adds an alpha channel (0.0–1.0) to control opacity. [S1]
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## 🧠 핵심 개념 (Core concepts)
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- **RGB = Red, Green, Blue** — colors are formed by combining these three light sources. [S1]
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- **Syntax** — `rgb(red, green, blue)`. [S1]
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- **Range** — each parameter (red, green, blue) defines the intensity of the color from 0 to 255. [S1]
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- **How it mixes** — `rgb(255, 0, 0)` is displayed as red, because red is set to its highest value (255) and the others are set to 0. [S1]
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- **Black and white** — black is `rgb(0, 0, 0)`; white is `rgb(255, 255, 255)`. [S1]
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- **RGBA** — RGBA extends RGB with an alpha channel for opacity: `rgba(red, green, blue, alpha)`, where alpha ranges from 0.0 (fully transparent) to 1.0 (not transparent). [S1]
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## 🧩 추출된 패턴 (Extracted patterns)
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- **Equal channels = gray** — setting red, green, and blue to the same value produces a shade of gray. [S1]
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- **Max one channel** — pushing a single channel to 255 while keeping the others at 0 produces a pure primary color (e.g. red, blue). [S1]
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- **Opacity via alpha** — append an alpha value with `rgba()` to make the same color progressively more transparent. [S1]
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## 📖 세부 내용 (Details)
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**RGB Value**
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RGB colors represent Red, Green, and Blue light sources. The syntax is `rgb(red, green, blue)`, where each parameter (red, green, and blue) defines the intensity of the color from 0 to 255. `rgb(255, 0, 0)` is displayed as red, because red is set to its highest value (255) and the others are set to 0. [S1]
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Examples of RGB color values shown on the page: [S1]
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```css
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rgb(255, 0, 0) /* red */
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rgb(0, 0, 255) /* blue */
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rgb(60, 179, 113) /* medium sea green */
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rgb(238, 130, 238)/* violet */
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rgb(255, 165, 0) /* orange */
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rgb(106, 90, 205) /* slate blue */
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```
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Black is `rgb(0, 0, 0)` and white is `rgb(255, 255, 255)`. [S1]
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**Shades of Gray**
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Shades of gray are often defined using equal values for all three light sources: [S1]
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```css
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rgb(60, 60, 60)
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rgb(90, 90, 90)
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rgb(120, 120, 120)
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rgb(180, 180, 180)
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rgb(210, 210, 210)
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rgb(240, 240, 240)
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```
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**RGBA Value**
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RGBA color values are an extension of RGB color values with an alpha channel, which specifies the opacity for a color. An RGBA color value is specified with `rgba(red, green, blue, alpha)`. The alpha parameter is a number between 0.0 (fully transparent) and 1.0 (not transparent at all). [S1]
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The page demonstrates the same color at increasing opacity: [S1]
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```css
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rgba(255, 99, 71, 0) /* fully transparent */
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rgba(255, 99, 71, 0.2)
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rgba(255, 99, 71, 0.4)
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rgba(255, 99, 71, 0.6)
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rgba(255, 99, 71, 0.8)
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rgba(255, 99, 71, 1.0) /* not transparent */
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```
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## 🛠️ 적용 사례 (Applied in summary)
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The color values above are the page's own demonstration examples. No external project/commit applications found in the source.
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## 💻 코드 패턴 (Code patterns)
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RGB function (language: CSS):
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```css
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selector {
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color: rgb(red, green, blue); /* each 0–255 */
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}
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```
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RGBA function with opacity:
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```css
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selector {
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color: rgba(red, green, blue, alpha); /* alpha 0.0–1.0 */
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}
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```
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## ⚖️ 비교 및 선택 기준 (Comparison & decision criteria)
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- **RGB vs RGBA** — use `rgb()` for an opaque color defined by red/green/blue intensities; use `rgba()` when the color also needs an opacity (alpha) value from 0.0 (fully transparent) to 1.0 (not transparent). [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:** 0.89
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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 HEX]], [[CSS HSL]], [[CSS Colors]], [[CSS Background Color]]
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- **참조 맥락:** Referenced whenever a color must be defined numerically by light intensity, or whenever an opacity channel is needed via RGBA.
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## 📚 출처 (Sources)
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- [S1] W3Schools — CSS RGB Colors — https://www.w3schools.com/css/css_colors_rgb.asp
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## 📝 변경 이력 (Change history)
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- 2026-06-23: Initial draft synthesized from the W3Schools "CSS RGB Colors" page (Astra wiki-curation, P-Reinforce v3.1 format).
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