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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
howto-css-three-columns How To - Three Column Layout Web_Recipes draft conceptual
3 column grid CSS float
B 0.81 2026-07-04 2026-07-04
howto
css
w3schools
layout
float
responsive
https://www.w3schools.com/howto/howto_css_three_columns.asp

HOWTO CSS Three Columns

🎯 한 줄 통찰 (One-line insight)

Beyond the standard equal-column formula (width: 33.33% for 3 equal float columns, same pattern as [[HOWTO CSS Four Columns]]), this recipe also shows UNEQUAL columns achieved by simply giving each column class its OWN explicit width (.left, .right { width: 25%; } .middle { width: 50%; }) instead of a shared class — proving that "N-column layout" isn't really about a fixed formula at all, just floats whose widths happen to sum to 100%, whether or not they're equal. [S1]

🧠 핵심 개념 (Core concepts)

  • Equal 3-column.column { float: left; width: 33.33%; } + .row:after clearfix. [S1]
  • Unequal 3-column — separate classes with independently-set widths that still sum to 100%: .left, .right { width: 25%; } .middle { width: 50%; }. [S1]
  • Same responsive collapse pattern@media (max-width: 600px) { .column { width: 100%; } }, identical breakpoint value to the Two/Four column recipes. [S1]

📖 세부 내용 (Details)

  • Equal columns: .column { float: left; width: 33.33%; } .row:after { content: ""; display: table; clear: both; }. [S1]
  • Unequal columns: .column { float: left; } .left, .right { width: 25%; } .middle { width: 50%; }. [S1]

⚖️ 모순 및 업데이트 (Contradictions & updates)

없음 — 신규 레시피, 기존 문서와 모순되는 내용 없음.

🛠️ 적용 사례 (Applied in summary)

동일 폭 3열과, 25%/50%/25%로 나뉜 비대칭 3열 두 가지 예제가 원문에서 나란히 제시됨. [S1]

💻 코드 패턴 (Code patterns)

Equal vs. unequal 3-column float layout (CSS):

/* Equal */
.column { float: left; width: 33.33%; }

/* Unequal -- widths just need to sum to 100% */
.left, .right { float: left; width: 25%; }
.middle { float: left; width: 50%; }

검증 상태 및 신뢰도

  • 상태: draft
  • 검증 단계: conceptual
  • 출처 신뢰도: B (W3Schools — widely used educational reference)
  • 신뢰 점수: 0.81
  • 중복 검사 결과: 신규 생성 (New discovery)

🔗 지식 그래프 (Knowledge Graph)

📚 출처 (Sources)

📝 변경 이력 (Change history)

  • 2026-07-04: Initial draft synthesized from the W3Schools "How To - Three Column Layout" recipe (Astra wiki-curation, P-Reinforce v3.1 format).