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W3Schools 튜토리얼을 P-Reinforce v3.1 포맷으로 위키화(영어 본문, 한/영 섹션 헤더). - Topic_HTML: 59문서 (튜토리얼+예제, 레퍼런스/메타 제외) - Topic_CSS: 190문서 (메인 + Advanced/Flexbox/Grid/RWD 전체) - Topic_JavaScript: 120문서 (코어 언어; Temporal/DOM상세/BOM/WebAPI/AJAX/jQuery/Graphics 등은 후속) 각 폴더 00_INDEX.md(MOC) 포함. 코드 verbatim, 미확인분은 "Not found in source" 표기. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
178 lines
6.3 KiB
Markdown
178 lines
6.3 KiB
Markdown
---
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id: css-image-sprites
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title: "CSS Image Sprites"
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category: "Frontend"
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status: "draft"
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verification_status: "conceptual"
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canonical_id: ""
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aliases: ["image sprite", "sprite image", "CSS sprites", "background-position sprite", "navigation sprite"]
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duplicate_of: ""
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source_trust_level: "B"
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confidence_score: 0.89
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created_at: 2026-06-23
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updated_at: 2026-06-23
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review_reason: ""
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merge_history: []
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tags: ["css", "web", "frontend", "w3schools", "sprites", "background-position", "performance"]
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raw_sources: ["https://www.w3schools.com/css/css_image_sprites.asp"]
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applied_in: []
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github_commit: ""
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---
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# [[CSS Image Sprites]]
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## 🎯 한 줄 통찰 (One-line insight)
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An image sprite packs many small images into one file, then uses `background-image` plus `background-position` offsets to display just the needed slice — cutting server requests and eliminating hover-load delay. [S1]
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## 🧠 핵심 개념 (Core concepts)
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- **Image sprite** — a collection of various small images put into one larger image file, called a "sprite image." [S1]
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- **Why sprites** — using a single sprite reduces the number of server requests and saves bandwidth versus loading many separate images. [S1]
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- **Two key properties** — sprites are implemented with `background-image` (the sprite file) and `background-position` (which slice to show). [S1]
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- **Transparent placeholder** — a tiny transparent image (`img_trans.gif`, `1×1`) can act as the element while CSS controls which part of the sprite is visible. [S1]
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- **Hover without extra loads** — hover effects shift `background-position` (e.g. `45px` down) to a different region of the sprite, so no additional image needs to load. [S1]
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## 🧩 추출된 패턴 (Extracted patterns)
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- **Slice selection** — fix an element's `width`/`height` to one icon's size and use a negative `background-position` to scroll the sprite so only that icon shows. [S1]
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- **Shorthand background** — combine file and position in one `background: url('sprite.gif') -47px 0;` declaration. [S1]
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- **Hover row swap** — keep horizontal offset, change the vertical offset on `:hover` to reveal a second row of the sprite for interactive feedback. [S1]
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## 📖 세부 내용 (Details)
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**What is an image sprite?**
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An image sprite is a collection of various small images put into one larger image file, called a "sprite image." This approach reduces the number of server requests and saves bandwidth. Sprites are implemented with the `background-image` and `background-position` properties. [S1]
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**Example 1 — Basic Image Sprites**
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Three elements (`#home`, `#prev`, `#next`) each set their own `width`/`height` and reference the same `img_navsprites.gif`, differing only by `background-position` so each shows a different icon. Transparent `1×1` images serve as the element bodies: [S1]
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```html
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<html>
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<head>
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<style>
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#home {
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width: 46px;
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height: 44px;
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background-image: url(img_navsprites.gif);
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background-position: 0 0;
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}
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#prev {
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width: 43px;
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height: 44px;
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background-image: url('img_navsprites.gif');
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background-position: -47px 0;
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}
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#next {
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width: 43px;
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height: 44px;
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background-image: url('img_navsprites.gif');
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background-position: -91px 0;
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}
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</style>
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</head>
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<body>
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<img id="home" src="img_trans.gif" width="1" height="1">
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<img id="prev" src="img_trans.gif" width="1" height="1">
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<img id="next" src="img_trans.gif" width="1" height="1">
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</body>
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</html>
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```
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**Example 2 — Navigation List**
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The sprite is applied to a navigation list (`<ul>`/`<li>`). The list uses relative/absolute positioning to lay items out horizontally, with each item's `left` offset and `background` shorthand isolating its icon from the sprite: [S1]
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```css
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#navlist {
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position: relative;
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}
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#navlist li {
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margin: 0;
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padding: 0;
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list-style: none;
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position: absolute;
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top: 0;
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}
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#navlist li, #navlist a {
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height: 44px;
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display: block;
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}
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#home {
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left: 0px;
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width: 46px;
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background: url('img_navsprites.gif') 0 0;
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}
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#prev {
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left: 60px;
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width: 43px;
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background: url('img_navsprites.gif') -47px 0;
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}
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#next {
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left: 120px;
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width: 43px;
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background: url('img_navsprites.gif') -91px 0;
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}
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```
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**Example 3 — Hover Effect**
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Adds interactivity by shifting `background-position` 45px down (to a hover row of `img_navsprites_hover.gif`) on `:hover`. Because all images preload in one file, there is no loading delay on hover: [S1]
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```css
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#home a:hover {
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background: url('img_navsprites_hover.gif') 0 -45px;
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}
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#prev a:hover {
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background: url('img_navsprites_hover.gif') -47px -45px;
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}
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#next a:hover {
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background: url('img_navsprites_hover.gif') -91px -45px;
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}
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```
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**Advantages highlighted:** a single server request instead of multiple image downloads; reduced bandwidth consumption; and no loading delay on hover effects since all images preload in one file. [S1]
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## 🛠️ 적용 사례 (Applied in summary)
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The page's three examples — basic sprite slices, a positioned navigation list, and a hover row swap — are the applied demonstrations. No external project/commit applications found in the source.
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## 💻 코드 패턴 (Code patterns)
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Display one slice of a sprite (language: CSS):
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```css
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#prev {
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width: 43px;
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height: 44px;
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background-image: url('img_navsprites.gif');
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background-position: -47px 0;
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}
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```
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Hover row swap with the background shorthand (language: CSS):
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```css
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#prev a:hover {
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background: url('img_navsprites_hover.gif') -47px -45px;
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}
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```
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## ⚖️ 모순 및 업데이트 (Contradictions & updates)
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No contradictions found in the source.
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## ✅ 검증 상태 및 신뢰도
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- **상태:** draft
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- **검증 단계:** conceptual (실제 적용 사례 발견 시 applied/validated로 승격 가능)
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- **출처 신뢰도:** B (W3Schools — widely used educational reference, not a primary standards body)
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- **신뢰 점수:** 0.89
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- **중복 검사 결과:** 신규 생성 (New discovery)
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## 🔗 지식 그래프 (Knowledge Graph)
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- **상위/루트:** [[CSS Tutorial]]
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- **관련 개념:** [[CSS Backgrounds]], [[CSS Position]], [[CSS Image Gallery]]
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- **참조 맥락:** Referenced when optimizing icon/asset delivery by consolidating many images into one file with positioned background slices.
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## 📚 출처 (Sources)
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- [S1] W3Schools — CSS Image Sprites — https://www.w3schools.com/css/css_image_sprites.asp
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## 📝 변경 이력 (Change history)
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- 2026-06-23: Initial draft synthesized from the W3Schools "CSS Image Sprites" page (Astra wiki-curation, P-Reinforce v3.1 format).
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