---
id: howto-css-split-screen
title: "How To - Split Screen 1/2"
category: "Web_Recipes"
status: "draft"
verification_status: "conceptual"
canonical_id: ""
aliases: ["50/50 split layout CSS"]
duplicate_of: ""
source_trust_level: "B"
confidence_score: 0.83
created_at: 2026-07-04
updated_at: 2026-07-04
review_reason: ""
merge_history: []
tags: ["howto", "css", "w3schools", "layout", "position"]
raw_sources: ["https://www.w3schools.com/howto/howto_css_split_screen.asp"]
applied_in: []
github_commit: ""
---

# [[HOWTO CSS Split Screen]]

## 🎯 한 줄 통찰 (One-line insight)
Instead of floating two 50%-width columns (the technique used in `[[HOWTO CSS Two Columns]]`), this recipe fixes BOTH halves to the viewport independently — `.split { position: fixed; height: 100%; width: 50%; }` combined with `.left { left: 0; }` / `.right { right: 0; }` pins each half to an opposite screen edge, meaning the two halves never scroll and always occupy exactly half the viewport regardless of page content length, which float-based columns cannot guarantee (floated columns follow document flow and CAN scroll). [S1]

## 🧠 핵심 개념 (Core concepts)
- **`position: fixed; width: 50%; height: 100%;`** — anchors each half to the viewport, not the document flow, so both halves are always visible and exactly half-width. [S1]
- **`left: 0` / `right: 0`** — pins one half to the left edge, the other to the right edge, with no gap or overlap. [S1]
- **Centered content inside each half** — reuses the absolute+transform centering technique (`position: absolute; top: 50%; left: 50%; transform: translate(-50%, -50%);`) already seen in `[[HOWTO CSS Center Vertical]]`, applied per-half. [S1]

## 📖 세부 내용 (Details)
- Split halves: `.split { height: 100%; width: 50%; position: fixed; z-index: 1; top: 0; overflow-x: hidden; } .left { left: 0; background-color: #111; } .right { right: 0; background-color: red; }`. [S1]
- Centered content: `.centered { position: absolute; top: 50%; left: 50%; transform: translate(-50%, -50%); text-align: center; } .centered img { width: 150px; border-radius: 50%; }`. [S1]

## ⚖️ 모순 및 업데이트 (Contradictions & updates)
- **fixed 포지셔닝이 float 기반 2단 컬럼과 근본적으로 다름**: `[[HOWTO CSS Two Columns]]`의 float 기반 2단 레이아웃은 문서 흐름을 따라 스크롤되지만, 이 레시피는 두 절반을 각각 position:fixed로 뷰포트에 고정해 항상 화면 절반씩을 차지하고 스크롤되지 않는다는 점이 핵심 차이로 확인됨. [S1]

## 🛠️ 적용 사례 (Applied in summary)
왼쪽에 여성 아바타, 오른쪽에 남성 아바타를 각각 배치해 화면을 정확히 반으로 나누는 예제가 원문에서 직접 제시됨. [S1]

## 💻 코드 패턴 (Code patterns)
Two viewport-fixed halves, each pinned to an opposite edge (CSS):
```css
.split {
  height: 100%;
  width: 50%;
  position: fixed;
  top: 0;
}
.left { left: 0; background-color: #111; }
.right { right: 0; background-color: red; }
```

## ✅ 검증 상태 및 신뢰도
- **상태:** draft
- **검증 단계:** conceptual
- **출처 신뢰도:** B (W3Schools — widely used educational reference)
- **신뢰 점수:** 0.83
- **중복 검사 결과:** 신규 생성 (New discovery)

## 🔗 지식 그래프 (Knowledge Graph)
- **상위/루트:** [[W3Schools HOW TO]]
- **관련 개념:** [[HOWTO CSS Two Columns]], [[HOWTO CSS Center Vertical]], [[HOWTO CSS Fixed Sidebar]]
- **참조 맥락:** CSS Layout & Positioning 섹션.

## 📚 출처 (Sources)
- [S1] W3Schools — How To - Split Screen 1/2 — https://www.w3schools.com/howto/howto_css_split_screen.asp

## 📝 변경 이력 (Change history)
- 2026-07-04: Initial draft synthesized from the W3Schools "How To - Split Screen 1/2" recipe (Astra wiki-curation, P-Reinforce v3.1 format).