---
id: w3css-borders
title: "W3CSS Borders"
category: "Programming_Language"
status: "draft"
verification_status: "conceptual"
canonical_id: ""
aliases: ["w3-border", "w3-leftbar", "W3.CSS 테두리"]
duplicate_of: ""
source_trust_level: "B"
confidence_score: 0.89
created_at: 2026-07-04
updated_at: 2026-07-04
review_reason: ""
merge_history: []
tags: ["w3css", "css-framework", "w3schools", "borders"]
raw_sources: ["https://www.w3schools.com/w3css/w3css_borders.asp"]
applied_in: []
github_commit: ""
---

# [[W3CSS Borders]]

## 🎯 한 줄 통찰 (One-line insight)
A border can be made "invisible" yet still functional as a hover trigger — setting `border:16px solid white` on an element paired with `w3-hover-border-green` creates a thick border that's visually undetectable against a white background until hovered, at which point it visibly appears in green, a trick that relies on the border occupying space without being seen. [S1]

## 🧠 핵심 개념 (Core concepts)
- **`w3-border` / `w3-border-{top,right,bottom,left}`** — adds borders to specific sides; `w3-border-0` removes all borders. [S1]
- **`w3-border-COLOR`** — sets border color (e.g. `w3-border-red`). [S1]
- **`w3-round-{small,large,xlarge,xxlarge}`** — rounds border corners at different intensities; plain `w3-round` is the default rounding. [S1]
- **`w3-topbar` / `w3-bottombar` / `w3-leftbar` / `w3-rightbar`** — add THICK single-side borders (heavier than normal `w3-border-*`). [S1]
- **`w3-hover-border-COLOR`** — changes border color specifically on mouse hover. [S1]
- **Invisible-until-hover border trick** — a white/matching-background border becomes visible only on hover via `w3-hover-border-*`. [S1]

## 📖 세부 내용 (Details)
- Directional borders: `<div class="w3-panel w3-border-left"><p>I have only a left border.</p></div>`. [S1]
- Colored border: `<div class="w3-panel w3-border w3-border-red"><p>I have red borders.</p></div>`. [S1]
- Thick bar border: `<div class="w3-panel w3-leftbar w3-border-blue w3-pale-blue"><p>I have a thick blue left border and a pale-blue background color.</p></div>`. [S1]
- Invisible-until-hover: `<div style="border:16px solid white" class="w3-panel w3-hover-border-green"><p>Thick (invisible) border that turns green on hover.</p></div>`. [S1]

## ⚖️ 모순 및 업데이트 (Contradictions & updates)
소스에서 모순되는 정보는 발견되지 않음.

## 🛠️ 적용 사례 (Applied in summary)
현재 발견된 실제 적용 사례가 없습니다 — 배경과 같은 색의 두꺼운 테두리를 호버 시에만 드러내는 트릭이 UI 인터랙션 디자인의 대표 실전 사례다. [S1]

## 💻 코드 패턴 (Code patterns)
Invisible border that reveals itself on hover (HTML):
```html
<div style="border:16px solid white" class="w3-panel w3-hover-border-green">
  <p>Thick (invisible) border that turns green on hover.</p>
</div>
```

## ✅ 검증 상태 및 신뢰도
- **상태:** draft
- **검증 단계:** conceptual
- **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:** [[W3.CSS Tutorial]]
- **관련 개념:** [[W3CSS Panels]], [[W3CSS Cards]], [[W3CSS Round]]
- **참조 맥락:** 패널의 시각적 강조 도구 — 카드(Cards) 챕터로 이어짐.

## 📚 출처 (Sources)
- [S1] W3Schools — W3.CSS Borders — https://www.w3schools.com/w3css/w3css_borders.asp

## 📝 변경 이력 (Change history)
- 2026-07-04: Initial draft synthesized from the W3Schools "W3.CSS Borders" page (Astra wiki-curation, P-Reinforce v3.1 format).
