2nd/10_Wiki/Topic_CSS/CSS_Background_Origin.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-background-origin	CSS Background Origin	Frontend	draft	conceptual		background-origin padding-box border-box origin content-box origin background positioning area background image start		B	0.88	2026-06-23	2026-06-23			css web frontend w3schools background background-origin	https://www.w3schools.com/css/css3_background_origin.asp

CSS Background Origin

🎯 한 줄 통찰 (One-line insight)

The background-origin property specifies where the background image is positioned relative to the box model — starting from the padding edge (default), the border edge, or the content edge. [S1]

🧠 핵심 개념 (Core concepts)

• background-origin — specifies where the background image is positioned. [S1]
• padding-box — the background image starts from the top-left corner of the padding edge; this is the default. [S1]
• border-box — the background image starts from the top-left corner of the border edge. [S1]
• content-box — the background image starts from the top-left corner of the content edge. [S1]
• Fixed-attachment caveat — this property has no effect if background-attachment is set to fixed. [S1]

🧩 추출된 패턴 (Extracted patterns)

• Box-model anchor pattern — the chosen value (padding-box / border-box / content-box) selects which box-model edge the image's top-left corner aligns to. [S1]
• Default-vs-inset pattern — border-box lets the image extend out under the border, while content-box insets it past the padding. [S1]

📖 세부 내용 (Details)

CSS background-origin Property The background-origin property specifies where the background image is positioned. [S1]

The property takes three different values: [S1]

• padding-box — the background image starts from the top-left corner of the padding edge. This is default. [S1]
• border-box — the background image starts from the top-left corner of the border edge. [S1]
• content-box — the background image starts from the top-left corner of the content edge. [S1]

Note: This property has no effect if the background-attachment property is set to fixed. [S1]

Example — the three origin values across three divs: [S1]

#div1 {
  border: 2px solid black;
  padding: 35px;
  background-image: url(img_flwr.gif);
  background-repeat: no-repeat;
  background-origin: padding-box;
}

#div2 {
  border: 2px solid black;
  padding: 35px;
  background-image: url(img_flwr.gif);
  background-repeat: no-repeat;
  background-origin: border-box;
}

#div3 {
  border: 2px solid black;
  padding: 35px;
  background-image: url(img_flwr.gif);
  background-repeat: no-repeat;
  background-origin: content-box;
}

CSS Background Properties

Property	Description
background	A shorthand property for setting all the background properties in one declaration
background-clip	Specifies the painting area of the background
background-image	Specifies one or more background images for an element
background-origin	Specifies where the background image(s) is/are positioned
background-size	Specifies the size of the background image(s)

[S1]

⚖️ 비교 및 선택 기준 (Comparison & decision criteria)

Choosing the origin value relative to the box model: [S1]

• padding-box (default) — image's top-left aligns to the padding edge; the usual behavior.
• border-box — image starts at the border edge, so it appears under the border.
• content-box — image starts at the content edge, inset past both border and padding. Note these only affect positioning of the image's origin; with background-attachment: fixed, the property has no effect. [S1]

🛠️ 적용 사례 (Applied in summary)

The page's three-div example (identical flower image with padding-box, border-box, and content-box) is the applied case. No external project/commit applications found in the source.

💻 코드 패턴 (Code patterns)

Anchor the background image to the content edge (language: CSS):

selector {
  border: 2px solid black;
  padding: 35px;
  background-image: url(img_flwr.gif);
  background-repeat: no-repeat;
  background-origin: content-box;
}

⚖️ 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 Background Clip, CSS Background Size, CSS Multiple Backgrounds
• 참조 맥락: Referenced when controlling exactly where a background image begins relative to border and padding.

📚 출처 (Sources)

• [S1] W3Schools — CSS Background Origin — https://www.w3schools.com/css/css3_background_origin.asp

📝 변경 이력 (Change history)

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