2nd/10_Wiki/Topic_CSS/CSS_Transitions.md

---
id: css-transitions
title: "CSS Transitions"
category: "Frontend"
status: "draft"
verification_status: "conceptual"
canonical_id: ""
aliases: ["transition", "CSS transition", "smooth transition", "hover transition", "transition shorthand"]
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", "transition", "animation"]
raw_sources: ["https://www.w3schools.com/css/css3_transitions.asp"]
applied_in: []
github_commit: ""
---

# [[CSS Transitions]]

## 🎯 한 줄 통찰 (One-line insight)
CSS transitions allow you to change property values smoothly, over a given duration, typically triggered by a state change such as `:hover`. [S1]

## 🧠 핵심 개념 (Core concepts)
- **Purpose** — CSS transitions allow you to change property values smoothly, over a given duration. [S1]
- **Shorthand** — the `transition` property is a shorthand for `transition-property`, `transition-duration`, `transition-timing-function`, and `transition-delay`. [S1]
- **Trigger required** — a transition runs when the targeted property changes value (for example, on `:hover`). [S1]
- **Per-property durations** — multiple properties can each be given their own duration in a single comma-separated `transition` declaration. [S1]

## 🧩 추출된 패턴 (Extracted patterns)
- **Property + duration** — at minimum specify which property to transition and how long it takes: `transition: width 2s;`. [S1]
- **State-change activation** — define the base rule, then change the property in a `:hover` (or similar) rule to drive the transition. [S1]
- **Comma-separated multi-property** — list several `property duration` pairs separated by commas to transition them concurrently with different timings. [S1]

## 📖 세부 내용 (Details)
**The CSS `transition` Property**
CSS transitions allows you to change property values smoothly, over a given duration. [S1]

**CSS Transition Example**
The following example shows a 100px * 100px `<div>` element. The `<div>` element has specified a transition effect for the width property, with a duration of 2 seconds: [S1]
```css
div {
  width: 100px;
  height: 100px;
  background-color: red;
  transition: width 2s;
}
```

**How to Trigger the Transition**
Now, we add a `div:hover` class that specifies a new value for the width property when a user mouses over the `<div>` element: [S1]
```css
div:hover {
  width: 300px;
}
```

**Change Multiple Property Values**
The following example adds a transition effect for the width, height, and background-color properties, with a duration of 2 seconds for the width, 4 seconds for the height, and 3 seconds for the background-color: [S1]
```css
div {
  transition: width 2s, height 4s, background-color 3s;
}
```

**CSS Transition Properties**
The following table lists the CSS transition properties: [S1]

| Property | Description |
|----------|-------------|
| `transition` | A shorthand property for setting the four transition properties into a single property |
| `transition-delay` | Specifies a delay (in seconds) for the transition effect |
| `transition-duration` | Specifies how many seconds or milliseconds a transition effect takes to complete |
| `transition-property` | Specifies the name of the CSS property the transition effect is for |
| `transition-timing-function` | Specifies the speed curve of the transition effect |

## 🛠️ 적용 사례 (Applied in summary)
The page applies a transition to a `<div>` whose width grows from 100px to 300px over 2 seconds on hover, and a multi-property example transitioning width, height, and background-color with distinct durations. No external project/commit applications found in the source.

## 💻 코드 패턴 (Code patterns)
Single-property transition triggered on hover (language: CSS):
```css
div {
  width: 100px;
  height: 100px;
  background-color: red;
  transition: width 2s;
}

div:hover {
  width: 300px;
}
```
Multiple properties with different durations:
```css
div {
  transition: width 2s, height 4s, background-color 3s;
}
```

## ⚖️ 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 Transition Timing]], [[CSS Animations]], [[CSS 3D Transforms]]
- **참조 맥락:** The entry point for smoothly animating property changes between two states; deeper control lives in the transition timing/delay properties.

## 📚 출처 (Sources)
- [S1] W3Schools — CSS Transitions — https://www.w3schools.com/css/css3_transitions.asp

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