---
id: howto-css-center-vertical
title: "How To - Center Elements Vertically"
category: "Web_Recipes"
status: "draft"
verification_status: "conceptual"
canonical_id: ""
aliases: ["vertical centering CSS", "transform translateY center"]
duplicate_of: ""
source_trust_level: "B"
confidence_score: 0.84
created_at: 2026-07-04
updated_at: 2026-07-04
review_reason: ""
merge_history: []
tags: ["howto", "css", "w3schools", "layout", "centering", "flexbox"]
raw_sources: ["https://www.w3schools.com/howto/howto_css_center-vertical.asp"]
applied_in: []
github_commit: ""
---

# [[HOWTO CSS Center Vertical]]

## 🎯 한 줄 통찰 (One-line insight)
This page teaches THREE distinct centering techniques and, notably, does NOT declare one universally superior — the `position: absolute` + `transform: translate(-50%, -50%)` method centers an element whose OWN size is unknown at author time (the negative-percentage transform shifts it back by exactly half of ITS OWN rendered width/height, computed at runtime), while the third technique (`display: flex; justify-content: center; align-items: center;`) achieves the identical visual result with far less code but requires flex layout on the PARENT rather than absolute positioning on the child — two fundamentally different mechanisms (offset math vs. layout algorithm) converging on the same output. [S1]

## 🧠 핵심 개념 (Core concepts)
- **Vertical-only centering** — `position: absolute; top: 50%; transform: translateY(-50%);` on a container with `position: relative`. [S1]
- **Vertical + horizontal centering (absolute method)** — `position: absolute; top: 50%; left: 50%; transform: translate(-50%, -50%);` — the transform shifts the element back by half its OWN width/height, which is why it works regardless of the element's actual size. [S1]
- **Flexbox method** — `display: flex; justify-content: center; align-items: center;` on the PARENT centers ANY child, both axes, with no transform math at all. [S1]
- **`-ms-transform` prefix** — included alongside the standard `transform` property for older IE/Edge compatibility. [S1]

## 📖 세부 내용 (Details)
- Vertical-only: `.container { height: 200px; position: relative; } .vertical-center { margin: 0; position: absolute; top: 50%; transform: translateY(-50%); }`. [S1]
- Both axes (absolute method): `.center { margin: 0; position: absolute; top: 50%; left: 50%; transform: translate(-50%, -50%); }`. [S1]
- Both axes (flexbox method): `.center { display: flex; justify-content: center; align-items: center; height: 200px; }`. [S1]

## ⚖️ 모순 및 업데이트 (Contradictions & updates)
없음 — 신규 레시피, 기존 문서와 모순되는 내용 없음.

## 🛠️ 적용 사례 (Applied in summary)
같은 텍스트를 세로만 중앙 정렬, 세로+가로 중앙 정렬(absolute), 그리고 flexbox로 중앙 정렬하는 3가지 방식이 원문에서 나란히 비교 제시됨. [S1]

## 💻 코드 패턴 (Code patterns)
Three centering techniques compared — absolute+transform vs. flexbox (CSS):
```css
/* Absolute + transform -- works for unknown element size */
.center-absolute {
  position: absolute;
  top: 50%; left: 50%;
  transform: translate(-50%, -50%);
}

/* Flexbox -- simplest, centers any child on both axes */
.center-flex {
  display: flex;
  justify-content: center;
  align-items: center;
  height: 200px;
}
```

## ✅ 검증 상태 및 신뢰도
- **상태:** draft
- **검증 단계:** conceptual
- **출처 신뢰도:** B (W3Schools — widely used educational reference)
- **신뢰 점수:** 0.84
- **중복 검사 결과:** 신규 생성 (New discovery)

## 🔗 지식 그래프 (Knowledge Graph)
- **상위/루트:** [[W3Schools HOW TO]]
- **관련 개념:** [[HOWTO CSS Center Button]], [[HOWTO CSS Center List]], [[HOWTO CSS Split Screen]]
- **참조 맥락:** CSS Layout & Positioning 섹션.

## 📚 출처 (Sources)
- [S1] W3Schools — How To - Center Elements Vertically — https://www.w3schools.com/howto/howto_css_center-vertical.asp

## 📝 변경 이력 (Change history)
- 2026-07-04: Initial draft synthesized from the W3Schools "How To - Center Elements Vertically" recipe (Astra wiki-curation, P-Reinforce v3.1 format).
