2nd/10_Wiki/Topic_Programming/Topic_CSS/CSS_Variables_MediaQueries.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-variables-in-media-queries	CSS Variables in Media Queries	Frontend	draft	conceptual		CSS custom properties media queries responsive CSS variables override variable in @media --fontsize media query variable breakpoints		B	0.88	2026-06-23	2026-06-23			css web frontend w3schools css-variables media-queries responsive	https://www.w3schools.com/css/css3_variables_mediaqueries.asp

CSS Variables in Media Queries

🎯 한 줄 통찰 (One-line insight)

CSS variables can be reassigned inside @media rules, so a single var()-driven design responds to screen size simply by overriding the variable's value at a breakpoint. [S1]

🧠 핵심 개념 (Core concepts)

• Media queries enable responsive styling — they allow you to set different styles for different devices/screen sizes. [S1]
• Variables are overridable per breakpoint — you can change a variable's value inside a media query, and every rule that reads it via var() updates automatically. [S1]
• Local vs. root scope — a variable defined on .container (e.g. --fontsize) can be overridden for .container inside a media query, while a variable on :root (e.g. --primary-bg-color) can be overridden globally inside the same query. [S1]

🧩 추출된 패턴 (Extracted patterns)

• Breakpoint override pattern — redefine the variable inside @media screen and (min-width: …) to switch its value above that width. [S1]
• Single-property responsiveness — changing --fontsize from 20px to 40px at min-width: 450px makes the font-size responsive without touching the font-size declaration itself. [S1]
• Multi-variable override — multiple variables (a local --fontsize on .container and a global --primary-bg-color on :root) can be overridden together within one media query. [S1]

📖 세부 내용 (Details)

Media queries let you set different style values for different devices. The page demonstrates overriding a CSS variable's value based on screen width: the --fontsize variable is 20px on small screens and becomes 40px on screens that are 450px or wider. [S1]

Example 1 — override a single variable at a breakpoint [S1]

:root {
  --primary-bg-color: #1e90ff;
  --primary-color: #ffffff;
}

body {
  background-color: var(--primary-bg-color);
}

.container {
  --fontsize: 20px;
  color: var(--primary-bg-color);
  background-color: var(--primary-color);
  padding: 15px;
  font-size: var(--fontsize);
}

.container h2 {
  border-bottom: 2px solid var(--primary-bg-color);
}

@media screen and (min-width: 450px) {
  .container {
    --fontsize: 40px;
  }
}

Example 2 — override multiple variables in the media query [S1] A second example modifies multiple variables inside the media query, additionally changing --primary-bg-color from the blue hex value to lightblue at the larger breakpoint: [S1]

:root {
  --primary-bg-color: #1e90ff;
  --primary-color: #ffffff;
}

body {
  background-color: var(--primary-bg-color);
}

.container {
  --fontsize: 20px;
  color: var(--primary-bg-color);
  background-color: var(--primary-color);
  padding: 15px;
  font-size: var(--fontsize);
}

.container h2 {
  border-bottom: 2px solid var(--primary-bg-color);
}

@media screen and (min-width: 450px) {
  .container {
    --fontsize: 40px;
  }
  :root {
    --primary-bg-color: lightblue;
  }
}

CSS var() function reference [S1]

Function	Description
var()	Inserts the value of a CSS variable

🛠️ 적용 사례 (Applied in summary)

The page's applied examples are a responsive card (.container): font size scales from 20px to 40px at the 450px breakpoint (Example 1), and in Example 2 the global background color also flips to lightblue above that width. No external project/commit applications found in the source.

💻 코드 패턴 (Code patterns)

Override a variable at a breakpoint (language: CSS):

.container {
  --fontsize: 20px;
  font-size: var(--fontsize);
}

@media screen and (min-width: 450px) {
  .container {
    --fontsize: 40px;
  }
}

⚖️ 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 Variables, CSS Variables and JavaScript, CSS Media Queries, CSS @property
• 참조 맥락: Referenced when building responsive designs whose tokens (font sizes, colors) change at viewport breakpoints via custom properties.

📚 출처 (Sources)

• [S1] W3Schools — CSS Variables in Media Queries — https://www.w3schools.com/css/css3_variables_mediaqueries.asp

📝 변경 이력 (Change history)

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