---
id: css-rwd-viewport
title: "CSS RWD Viewport"
category: "Frontend"
status: "draft"
verification_status: "conceptual"
canonical_id: ""
aliases: ["viewport meta tag", "responsive viewport", "device-width", "RWD viewport", "viewport scaling"]
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", "responsive", "viewport"]
raw_sources: ["https://www.w3schools.com/css/css_rwd_viewport.asp"]
applied_in: []
github_commit: ""
---

# [[CSS RWD Viewport]]

## 🎯 한 줄 통찰 (One-line insight)
The viewport is the user's visible area of a web page, and adding a single `<meta name="viewport">` tag tells the browser to match the page width to the device and set the initial zoom so content fits without horizontal scrolling. [S1]

## 🧠 핵심 개념 (Core concepts)
- **Viewport definition** — the viewport is the user's visible area of a web page, and it varies with the device (smaller on a phone than on a computer screen). [S1]
- **The viewport meta tag** — to give the browser instructions on how to control the page's dimensions and scaling, every web page should include the viewport `<meta>` tag. [S1]
- **`width=device-width`** — sets the width of the page to follow the screen-width of the device. [S1]
- **`initial-scale=1.0`** — sets the initial zoom level when the page is first loaded by the browser. [S1]
- **No horizontal scrolling** — users are used to scrolling websites vertically but not horizontally; forcing horizontal scrolling or zoom-out degrades the experience. [S1]

## 🧩 추출된 패턴 (Extracted patterns)
- **Standard responsive header line** — placing the viewport meta tag in the `<head>` of every page is the baseline step for responsive web design. [S1]
- **Size content to the viewport** — keep elements fluid rather than fixed-width so they never exceed the device's visible area. [S1]

## 📖 세부 내용 (Details)
**What is The Viewport?**
The viewport is the user's visible area of a web page. The viewport varies with the device, and will be smaller on a mobile phone than on a computer screen. [S1]

**Setting The Viewport**
To give the browser instructions on how to control the page's dimensions and scaling, you should include the following `<meta>` viewport element in all your web pages: [S1]
```html
<meta name="viewport" content="width=device-width, initial-scale=1.0">
```
This gives the browser instructions on how to control the page's dimensions and scaling. The `width=device-width` part sets the width of the page to follow the screen-width of the device (which will vary depending on the device). The `initial-scale=1.0` part sets the initial zoom level when the page is first loaded by the browser. [S1]

The page demonstrates the visual difference between a page without the viewport meta tag and a page with it. **Tip:** If you are browsing this page with a phone or a tablet, you can click on the two links above to see the difference. (Those comparison demos are links/images only — no inline code.) [S1]

**Size Content to The Viewport**
Users are used to scroll websites vertically both on desktop and mobile devices - but not horizontally! So, if the user is forced to scroll horizontally, or zoom out, to see the whole web page it results in a poor user experience. Some additional rules to follow: [S1]

1. **Do NOT use large fixed-width elements** — For example, if an image has a width wider than the viewport, it causes the viewport to scroll horizontally. [S1]
2. **Do NOT let the content rely on a particular width to render well** — Since screen dimensions vary widely between devices, content should not rely on a particular viewport width to render well. [S1]
3. **Use CSS media queries to apply different styling for small and large screens** — Setting large absolute CSS widths for page elements will cause the elements to be too wide for smaller devices. Instead, consider using relative width values, such as `width: 100%`. [S1]

## 🛠️ 적용 사례 (Applied in summary)
The meta viewport tag above is the page's own applied example — the one line W3Schools instructs to place in all web pages. No external project/commit applications found in the source.

## 💻 코드 패턴 (Code patterns)
The viewport meta tag (language: HTML):
```html
<meta name="viewport" content="width=device-width, initial-scale=1.0">
```

## ⚖️ 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 RWD Grid View]], [[CSS RWD Media Queries]], [[CSS RWD Images]]
- **참조 맥락:** The first technical step in responsive web design, referenced before media queries and fluid grids are applied.

## 📚 출처 (Sources)
- [S1] W3Schools — CSS RWD Viewport — https://www.w3schools.com/css/css_rwd_viewport.asp

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