---
id: css-rgb-colors
title: "CSS RGB Colors"
category: "Frontend"
status: "draft"
verification_status: "conceptual"
canonical_id: ""
aliases: ["RGB", "rgb()", "RGBA", "rgba()", "RGB color model", "CSS RGB values"]
duplicate_of: ""
source_trust_level: "B"
confidence_score: 0.89
created_at: 2026-06-23
updated_at: 2026-06-23
review_reason: ""
merge_history: []
tags: ["css", "web", "frontend", "w3schools", "color", "rgb", "rgba"]
raw_sources: ["https://www.w3schools.com/css/css_colors_rgb.asp"]
applied_in: []
github_commit: ""
---

# [[CSS RGB Colors]]

## 🎯 한 줄 통찰 (One-line insight)
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]

## 🧠 핵심 개념 (Core concepts)
- **RGB = Red, Green, Blue** — colors are formed by combining these three light sources. [S1]
- **Syntax** — `rgb(red, green, blue)`. [S1]
- **Range** — each parameter (red, green, blue) defines the intensity of the color from 0 to 255. [S1]
- **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]
- **Black and white** — black is `rgb(0, 0, 0)`; white is `rgb(255, 255, 255)`. [S1]
- **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]

## 🧩 추출된 패턴 (Extracted patterns)
- **Equal channels = gray** — setting red, green, and blue to the same value produces a shade of gray. [S1]
- **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]
- **Opacity via alpha** — append an alpha value with `rgba()` to make the same color progressively more transparent. [S1]

## 📖 세부 내용 (Details)
**RGB Value**
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]

Examples of RGB color values shown on the page: [S1]
```css
rgb(255, 0, 0)    /* red */
rgb(0, 0, 255)    /* blue */
rgb(60, 179, 113) /* medium sea green */
rgb(238, 130, 238)/* violet */
rgb(255, 165, 0)  /* orange */
rgb(106, 90, 205) /* slate blue */
```

Black is `rgb(0, 0, 0)` and white is `rgb(255, 255, 255)`. [S1]

**Shades of Gray**
Shades of gray are often defined using equal values for all three light sources: [S1]
```css
rgb(60, 60, 60)
rgb(90, 90, 90)
rgb(120, 120, 120)
rgb(180, 180, 180)
rgb(210, 210, 210)
rgb(240, 240, 240)
```

**RGBA Value**
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]

The page demonstrates the same color at increasing opacity: [S1]
```css
rgba(255, 99, 71, 0)    /* fully transparent */
rgba(255, 99, 71, 0.2)
rgba(255, 99, 71, 0.4)
rgba(255, 99, 71, 0.6)
rgba(255, 99, 71, 0.8)
rgba(255, 99, 71, 1.0)  /* not transparent */
```

## 🛠️ 적용 사례 (Applied in summary)
The color values above are the page's own demonstration examples. No external project/commit applications found in the source.

## 💻 코드 패턴 (Code patterns)
RGB function (language: CSS):
```css
selector {
  color: rgb(red, green, blue); /* each 0–255 */
}
```
RGBA function with opacity:
```css
selector {
  color: rgba(red, green, blue, alpha); /* alpha 0.0–1.0 */
}
```

## ⚖️ 비교 및 선택 기준 (Comparison & decision criteria)
- **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]

## ⚖️ 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:** 0.89
- **중복 검사 결과:** 신규 생성 (New discovery)

## 🔗 지식 그래프 (Knowledge Graph)
- **상위/루트:** [[CSS Tutorial]]
- **관련 개념:** [[CSS HEX]], [[CSS HSL]], [[CSS Colors]], [[CSS Background Color]]
- **참조 맥락:** Referenced whenever a color must be defined numerically by light intensity, or whenever an opacity channel is needed via RGBA.

## 📚 출처 (Sources)
- [S1] W3Schools — CSS RGB Colors — https://www.w3schools.com/css/css_colors_rgb.asp

## 📝 변경 이력 (Change history)
- 2026-06-23: Initial draft synthesized from the W3Schools "CSS RGB Colors" page (Astra wiki-curation, P-Reinforce v3.1 format).