2nd/10_Wiki/Topic_CSS/CSS_Grid_12Column.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-grid-12-column-layout	CSS Grid 12-column Layout	Frontend	draft	conceptual		12-column grid repeat(12, 1fr) responsive grid layout mobile first grid named grid lines col-start grid 12 column responsive		B	0.88	2026-06-23	2026-06-23			css web frontend w3schools grid responsive	https://www.w3schools.com/css/css_grid_12column.asp

CSS Grid 12-column Layout

🎯 한 줄 통찰 (One-line insight)

A 12-column grid divides horizontal space into 12 equal fluid 1fr columns via grid-template-columns: repeat(12, [col-start] 1fr), and because 12 is highly divisible, items can be placed and resized with grid-column spans and progressively rearranged through mobile-first media queries. [S1]

🧠 핵심 개념 (Core concepts)

• 12-column grid — a common and flexible method for structuring web page content, particularly for responsive web design. [S1]
• Equal-width division — the system divides the available horizontal space into 12 equal-width columns, allowing precise placement and sizing of elements. [S1]
• Flexibility — 12 is highly divisible, so designers can create halves, thirds, and quarters (2 columns of 6, 3 columns of 4, 4 columns of 3). [S1]
• Responsiveness — a 12-column grid is ideal for building responsive websites that adapt to different screen sizes (desktop, tablet, or mobile) with media queries. [S1]
• Efficiency — having a pre-defined structure speeds up the design process. [S1]

🧩 추출된 패턴 (Extracted patterns)

• repeat(12, [col-start] 1fr) — repeat(12,..) repeats the track definition 12 times; [col-start] creates a named grid line useful for placing items at specific start points; 1fr is a fractional unit giving each column an equal, fluid width. [S1]
• Item placement options — place/size items with grid-column: span <number>;, grid-column: <start-line> / span <number>;, or grid-column: <start-line> / <end-line>;. [S1]
• Mobile-first media queries — design for mobile first, showing sections in source order for small screens, then enhance at 576px and 768px breakpoints. [S1]

📖 세부 내용 (Details)

A 12-column grid is a common and flexible method for structuring web page content, particularly for responsive web design. The 12-column grid system divides the available horizontal space into 12 equal-width columns, allowing for precise placement and sizing of elements within the layout. [S1]

Benefits [S1]

• Flexibility: the number 12 is highly divisible. Designers can easily create designs with halves, thirds, and quarters (2 columns of 6, 3 columns of 4, 4 columns of 3).
• Responsiveness: a 12-column grid is ideal for building responsive websites that adapt to different screen sizes (desktop, tablet, or mobile) with media queries.
• Efficiency: having a pre-defined structure speeds up the design process.

Implementation [S1]

• Define grid container: apply display: grid; to the container element.
• Create 12 columns: use grid-template-columns: repeat(12, [col-start] 1fr);, where repeat(12,..) tells the grid to repeat the following track definition 12 times (resulting in 12 columns), [col-start] creates a named grid line (useful for placing grid items at specific start points), and 1fr is a fractional unit that represents one fraction of the total available space (so each of the 12 columns will be an equal, fluid width).
• Place grid items: grid items can then be placed and sized across these 12 columns using grid-column, via grid-column: span <number>;, grid-column: <start-line> / span <number>;, or grid-column: <start-line> / <end-line>;.
• Media queries: always design for mobile first. Display the sections in the source order (from top to bottom) for screens less than 576 pixels wide, then enhance at 576px and 768px breakpoints. [S1]

Complete example [S1]

* {
  box-sizing: border-box;
}

.container {
  display: grid;
  grid-template-columns: repeat(12, [col-start] 1fr);
  gap: 20px;
}

nav ul {
  list-style: none;
  margin: 0;
  padding: 0;
}

/* Mobile first */
.container > * {
  border: 1px solid green;
  background-color: beige;
  padding: 10px;
  grid-column: col-start / span 12;
}

@media (min-width: 576px) {
  .sidebar {
    grid-column: col-start / span 3;
    grid-row: 3;
  }
  .ads {
    grid-column: col-start / span 3;
  }
  .content, .footer {
    grid-column: col-start 4 / span 9;
  }
  nav ul {
    display: flex;
    justify-content: space-between;
  }
}

@media (min-width: 768px) {
  .nav {
    grid-column: col-start / span 2;
    grid-row: 2 / 4;
  }
  .content {
    grid-column: col-start 3 / span 8;
    grid-row: 2 / 4;
  }
  .sidebar {
    grid-column: col-start 11 / span 2;
  }
  .ads {
    grid-column: col-start 11 / span 2;
  }
  .footer {
    grid-column: col-start / span 12;
  }
  nav ul {
    flex-direction: column;
  }
}

🛠️ 적용 사례 (Applied in summary)

The page's applied case is a complete responsive page layout: a 12-column container with gap: 20px, full-width stacking on mobile, a 3/9 split at 576px, and a nav/content/sidebar/ads/footer arrangement at 768px. No external project/commit applications found in the source.

💻 코드 패턴 (Code patterns)

Define a 12-column fluid grid (language: CSS):

.container {
  display: grid;
  grid-template-columns: repeat(12, [col-start] 1fr);
  gap: 20px;
}

Mobile-first full-width default, then span at a breakpoint:

.container > * {
  grid-column: col-start / span 12;
}

@media (min-width: 576px) {
  .content, .footer {
    grid-column: col-start 4 / span 9;
  }
}

⚖️ 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 Grid Items, CSS Grid Item Named, CSS RWD Intro
• 참조 맥락: A concrete responsive layout method built on CSS Grid and media queries.

📚 출처 (Sources)

• [S1] W3Schools — CSS Grid 12-column Layout — https://www.w3schools.com/css/css_grid_12column.asp

📝 변경 이력 (Change history)

• 2026-06-23: Initial draft synthesized from the W3Schools "CSS Grid 12-column Layout" page (Astra wiki-curation, P-Reinforce v3.1 format).