---
id: css-vertical-align
title: "CSS Vertical Align"
category: "Frontend"
status: "draft"
verification_status: "conceptual"
canonical_id: ""
aliases: ["vertical align", "vertical centering", "flexbox center", "grid place-items", "transform translate center"]
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", "alignment", "flexbox", "grid"]
raw_sources: ["https://www.w3schools.com/css/css_align_vertical.asp"]
applied_in: []
github_commit: ""
---

# [[CSS Vertical Align]]

## 🎯 한 줄 통찰 (One-line insight)
Modern CSS centers content vertically with three approaches — Flexbox (`align-items: center`), Grid (`place-items: center`), or Position + Transform (`top/left: 50%` with `translate(-50%, -50%)`) — the last being the common technique for elements of unknown or dynamic dimensions. [S1]

## 🧠 핵심 개념 (Core concepts)
- **Flexbox vertical centering** — `display: flex` with `justify-content: center` and `align-items: center` centers content within a sized container. [S1]
- **Grid vertical centering** — `display: grid` with `place-items: center` achieves the same centering effect. [S1]
- **Position + Transform** — `position: absolute` with `top: 50%`, `left: 50%`, and `transform: translate(-50%, -50%)` centers content. [S1]
- **Use Position + Transform for unknown sizes** — it is a common technique when dealing with elements of unknown or dynamic dimensions. [S1]
- **Container setup** — the examples use a 200px-height container with a 3px solid green border. [S1]

## 🧩 추출된 패턴 (Extracted patterns)
- **Flexbox both-axis center** — `display: flex; justify-content: center; align-items: center;`. [S1]
- **Grid one-liner center** — `display: grid; place-items: center;`. [S1]
- **Translate -50% center** — absolutely position the child at 50%/50% then pull it back by half its own size with `translate(-50%, -50%)`. [S1]

## 📖 세부 내용 (Details)
**Center Align with Flexbox** [S1]
```css
.center {
  display: flex;
  justify-content: center;
  align-items: center;
  height: 200px;
  border: 3px solid green;
}
```

**Center Align with Grid** [S1]
```css
.center {
  display: grid;
  place-items: center;
  height: 200px;
  border: 3px solid green;
}
```

**Center Align with `position` and `transform`**
For elements of unknown or dynamic dimensions, this is a common technique. The example sets `margin: 0` on the paragraph and centers it: [S1]
```css
.container p {
  margin: 0;
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
}
```
The page directs readers to the 2D Transforms chapter for a deeper understanding of the `transform` property. [S1]

## 🛠️ 적용 사례 (Applied in summary)
The page's own applied examples are vertically centering content with Flexbox, with Grid (`place-items`), and with Position + Transform inside a 200px-height bordered container. No external project/commit applications found in the source.

## 💻 코드 패턴 (Code patterns)
Position + transform centering (language: CSS):
```css
.container p {
  margin: 0;
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
}
```

## ⚖️ 비교 및 선택 기준 (Comparison & decision criteria)
- **Flexbox vs Grid vs Position+Transform** — Flexbox and Grid are modern container-driven techniques for vertical centering; Position + Transform is the common choice when the element has unknown or dynamic dimensions because `translate(-50%, -50%)` offsets by the element's own measured size. [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 Center Align]], [[CSS Horizontal Align]], [[CSS Flexbox]], [[CSS Grid]]
- **참조 맥락:** Referenced when vertically centering content, especially elements whose height is not known in advance.

## 📚 출처 (Sources)
- [S1] W3Schools — CSS Vertical Align — https://www.w3schools.com/css/css_align_vertical.asp

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