2nd/10_Wiki/Topic_CSS/CSS_Supports_Rule.md

id, title, category, status, verification_status, canonical_id, aliases, duplicate_of, source_trust_level, confidence_score, created_at, updated_at, review_reason, merge_history, tags, raw_sources, applied_in, github_commit

id	title	category	status	verification_status	canonical_id	aliases	duplicate_of	source_trust_level	confidence_score	created_at	updated_at	review_reason	merge_history	tags	raw_sources	applied_in	github_commit
css-supports	CSS @supports	Frontend	draft	conceptual		@supports feature queries CSS feature query supports rule progressive enhancement CSS browser feature detection CSS		B	0.89	2026-06-23	2026-06-23			css web frontend w3schools at-rule progressive-enhancement	https://www.w3schools.com/css/css_supports_rule.asp

CSS @supports

🎯 한 줄 통찰 (One-line insight)

The @supports rule (a feature query) checks whether the browser supports a specific CSS property or value and applies styles only when it does, letting you define fallbacks for unsupported features. [S1]

🧠 핵심 개념 (Core concepts)

• @supports rule — lets you check if the browser supports a specific CSS property or value, and define fallback styles if the feature is not supported. [S1]
• Conditional application — useful for applying styles only when the browser can handle them. [S1]
• Operators — you can use and, or, and not for multiple conditions. [S1]
• Negation — not applies styles only when a feature is not supported. [S1]
• Fallback rule (Note) — always provide fallback styles outside of @supports, for older browsers. [S1]

🧩 추출된 패턴 (Extracted patterns)

• Test then enhance — write base/fallback styles normally, then wrap the enhanced styles in @supports (property: value) { ... }. [S1]
• Combine conditions — chain feature tests with and/or (e.g. (display: grid) and (gap: 10px)). [S1]
• Negative guard — use @supports not (...) to style a warning or fallback path when a feature is absent. [S1]

📖 세부 내용 (Details)

The @supports rule lets you check if the browser supports a specific CSS property or value, and to define fallback styles if the feature is not supported. This is useful for applying styles only when the browser can handle them. [S1]

Basic syntax [S1]

@supports (property: value) {
  /* CSS rules to apply if condition is true */
}

Example — flex fallback [S1]

/* use this CSS if the browser does not support display: flex */
.container {
  float: left;
  width: 100%;
}

/* use this CSS if the browser supports display: flex */
@supports (display: flex) {
  .container {
    display: flex;
  }
}

Example — grid fallback [S1]

/* use this CSS if the browser does not support display: grid */
.container {
  display: table;
  width: 90%;
  background-color: #2196F3;
  padding: 10px;
}

/* use this CSS if the browser supports display: grid */
@supports (display: grid) {
  .container {
    display: grid;
    grid: auto;
    grid-gap: 10px;
    background-color: #2196F3;
    padding: 10px;
  }
}

Negating with not — you can use not to apply styles only when a feature is not supported: [S1]

@supports not (display: grid) {
  .warning {
    background-color: pink;
    padding: 10px;
    border: 1px solid red;
  }
}

Combining conditions — you can use and, or, and not for multiple conditions: [S1]

@supports (display: grid) and (gap: 10px) {
  .container {
    display: grid;
    gap: 10px;
  }
}

Note: Always provide fallback styles outside of @supports, for older browsers. [S1]

Reference table [S1]

At-rule	Description
@supports	Used to test whether a browser supports a CSS feature

🛠️ 적용 사례 (Applied in summary)

The page's applied cases are progressive-enhancement layouts: a float fallback enhanced to flex, a table fallback enhanced to grid, a not-guarded warning box, and a combined (display: grid) and (gap: 10px) query. No external project/commit applications found in the source.

💻 코드 패턴 (Code patterns)

Feature query with fallback (language: CSS):

.container {
  float: left;
  width: 100%;
}

@supports (display: flex) {
  .container {
    display: flex;
  }
}

Negative feature query:

@supports not (display: grid) {
  .warning {
    background-color: pink;
    padding: 10px;
    border: 1px solid red;
  }
}

Combined conditions:

@supports (display: grid) and (gap: 10px) {
  .container {
    display: grid;
    gap: 10px;
  }
}

⚖️ 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 Grid 12-column Layout, CSS RWD Intro, CSS Grid Align
• 참조 맥락: Browser feature detection for safely adopting newer CSS layout features with fallbacks.

📚 출처 (Sources)

• [S1] W3Schools — CSS @supports — https://www.w3schools.com/css/css_supports_rule.asp

📝 변경 이력 (Change history)

• 2026-06-23: Initial draft synthesized from the W3Schools "CSS @supports" page (Astra wiki-curation, P-Reinforce v3.1 format).