2nd/10_Wiki/Topic_CSS/CSS_Accessibility.md

---
id: css-accessibility
title: "CSS Accessibility"
category: "Frontend"
status: "draft"
verification_status: "conceptual"
canonical_id: ""
aliases: ["CSS a11y", "accessible CSS", "focus styles", "color contrast", "prefers-reduced-motion"]
duplicate_of: ""
source_trust_level: "B"
confidence_score: 0.88
created_at: 2026-06-23
updated_at: 2026-06-23
review_reason: ""
merge_history: []
tags: ["css", "web", "frontend", "w3schools", "accessibility", "a11y", "focus"]
raw_sources: ["https://www.w3schools.com/css/css_accessibility.asp"]
applied_in: []
github_commit: ""
---

# [[CSS Accessibility]]

## 🎯 한 줄 통찰 (One-line insight)
Accessible CSS rests on a few habits: high color contrast, readable fonts, visible focus indicators, semantic HTML, and respecting user preferences such as reduced motion. [S1]

## 🧠 핵심 개념 (Core concepts)
- **High color contrast** — ensure foreground text stands out strongly against the background. [S1]
- **Readable typography** — use legible font families, adequate font sizes, and generous line height. [S1]
- **Visible focus indicators** — interactive elements must have a clear visual focus style. [S1]
- **Don't hide focus** — never remove the focus outline without providing a visible replacement. [S1]
- **Semantic HTML** — style semantic elements (`<nav>`, `<aside>`) rather than generic `<div>`s. [S1]
- **Respect user preferences** — honor settings like reduced motion. [S1]

## 🧩 추출된 패턴 (Extracted patterns)
- **Focus-ring pattern** — apply a visible `outline` on `:focus` for links, buttons, and inputs. [S1]
- **Reduced-motion pattern** — wrap a global animation/transition kill-switch in a `prefers-reduced-motion: reduce` media query. [S1]

## 📖 세부 내용 (Details)
**High color contrast.** Use a strong contrast between text and background. The good example uses an `#ffffff` background with `#000000` text; the bad example uses an `#eeeeee` background with `#cccccc` text (too low contrast). [S1]

**Font, size, and line height.** Choose readable typography. The good example uses Arial/sans-serif at `1rem` with `1.6` line-height; the bad example uses Georgia/serif at `12px`, italic, small-caps variant, with `90%` line-height. [S1]

**Visible focus indicators.** Always use the `:focus` pseudo-class to ensure that interactive elements (like links, buttons, input fields) have a clear visual focus style. [S1]
```css
a:focus, button:focus, input:focus {
  outline: 2px solid orange;
}
```

**Avoid hiding focus.** Never use `outline: none` without replacement styling. Use a visible alternative such as `outline: 2px solid orange`. [S1]

**Semantic HTML with CSS.** Style `<nav>` and `<aside>` elements (for example with backgrounds) instead of generic `<div>` tags, so the document remains meaningful to assistive technology. [S1]

**Respect user preferences (reduced motion).** Honor a user's reduced-motion preference by disabling animations and transitions inside a media query. [S1]
```css
@media (prefers-reduced-motion: reduce) {
  * {
    animation: none !important;
    transition: none !important;
  }
}
```

(Note: the exact color/font example code boxes for the contrast and typography sections were described but not captured verbatim from the source. — Not found in source.)

## 🛠️ 적용 사례 (Applied in summary)
The page's applied demonstrations contrast accessible vs inaccessible choices (white-on-black vs grey-on-light-grey; Arial 1rem/1.6 vs Georgia 12px italic), add a visible orange focus outline to links/buttons/inputs, and disable motion for users who request reduced motion. No external project/commit applications found in the source.

## 💻 코드 패턴 (Code patterns)
Visible focus ring (language: CSS):
```css
a:focus, button:focus, input:focus {
  outline: 2px solid orange;
}
```
Respect reduced-motion preference (language: CSS):
```css
@media (prefers-reduced-motion: reduce) {
  * {
    animation: none !important;
    transition: none !important;
  }
}
```

## ⚖️ 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:** 0.88
- **중복 검사 결과:** 신규 생성 (New discovery)

## 🔗 지식 그래프 (Knowledge Graph)
- **상위/루트:** [[CSS Tutorial]]
- **관련 개념:** [[CSS !important]], [[CSS Optimization]], [[CSS Website Layout]]
- **참조 맥락:** Consulted when making a page usable for keyboard users, low-vision users, and people sensitive to motion.

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

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