/* ============================================================
   Lecture · 관계대수 (3과목 · 관계대수) — slide layout extensions
   Builds on /colors_and_type.css and /slides/_slide.css
   ─ 22강 DB시스템구성 lecture.css 전체 계승(comp-grid·dg-box/dg-arr SVG·flow·
     obj-grid·step-grid·cmp-tbl.compact·tree-frame+dg-* + def-box·metaphor·
     mnemonic·real·pass-tip·trap-row·q-source 코어 재사용).
   ─ 신규: 연산자 기호 카드(op-grid·op-card — σ·π·⋈·÷ 순수 yellow / ∪·∩·−·× 집합 dark).
     기호표가 25강 시그니처. 기호는 텍스트 렌더(폰트 family 변경 금지 — 브라우저
     per-glyph fallback로 ⋈ 등 수학기호 자동 대체).
   ─ 코어(_slide.css) 승격 컴포넌트는 재정의하지 않음:
     def-box · metaphor · mnemonic · real · pass-tip
     · cmp-tbl · trap-row · q-source · tbl.compact · callout.compact
   ============================================================ */

/* ---------- 4-objective grid (학습 목표) — 08·10강 패턴 재사용 ---------- */
.obj-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 14px;
}
.obj-item {
  display: grid;
  grid-template-columns: 52px 1fr;
  gap: 16px;
  align-items: center;
  padding: 16px 20px;
  background: var(--ink-50);
  border: 1.5px solid var(--ink-200);
  border-radius: 12px;
}
.obj-item .badge {
  width: 52px;
  height: 52px;
  background: var(--eduwill-yellow);
  color: var(--ink-1000);
  display: grid;
  place-items: center;
  font: 800 26px/1 var(--font-sans);
  border-radius: 12px;
}
.obj-item h3 { margin: 0; font: 800 18px/1.15 var(--font-sans); color: var(--ink-1000); }
.obj-item p  { margin: 4px 0 0; font-size: 13px; color: var(--ink-700); line-height: 1.4; }

/* ============================================================
   흐름 노드 행 — A → B → C inline 시퀀스
   08·10·11강 .flow 재사용 (σ→π 중첩 처리순서·SQL 다리 흐름)
   ============================================================ */
.flow {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  flex-wrap: wrap;
}
.flow .box {
  padding: 10px 16px;
  border-radius: 10px;
  background: white;
  border: 1.5px solid var(--ink-300);
  font: 700 16px/1.2 var(--font-sans);
  color: var(--ink-900);
  text-align: center;
}
.flow .box.dark { background: var(--ink-1000); color: white; border-color: var(--ink-1000); }
.flow .box.mid  { background: var(--eduwill-yellow); color: var(--ink-1000); border-color: var(--eduwill-yellow); font-weight: 800; }
.flow .box small { display: block; font-size: 11px; font-weight: 600; opacity: 0.7; margin-top: 2px; }
.flow .arw { color: var(--ink-500); font-size: 20px; font-weight: 800; }

/* ============================================================
   ▼▼▼ 연산자 기호 카드 (op-grid·op-card) — 25강 신규 시그니처 ▼▼▼
   ─ 순수 4종(σ·π·⋈·÷) = yellow top bar / 집합 4종(∪·∩·−·×) = dark top bar
   ─ 8연산자 종합은 c4 그리드 2행으로 결합
   ============================================================ */
.op-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 10px; }
.op-grid.c2 { grid-template-columns: repeat(2, 1fr); }
.op-card {
  background: white;
  border: 1.5px solid var(--ink-200);
  border-top: 5px solid var(--eduwill-yellow);
  border-radius: 12px;
  padding: 12px 10px 11px;
  text-align: center;
}
.op-card.set { border-top-color: var(--ink-1000); }
.op-card .sym {
  font: 800 34px/1 var(--font-sans);
  color: var(--ink-1000);
  letter-spacing: -0.01em;
}
.op-card.set .sym { color: var(--ink-700); }
.op-card .nm { margin-top: 6px; font: 800 14px/1.1 var(--font-sans); color: var(--ink-1000); }
.op-card .en { font-size: 10.5px; font-weight: 700; color: var(--ink-500); letter-spacing: 0.02em; }
.op-card .ds { margin-top: 6px; font-size: 11.5px; line-height: 1.4; color: var(--ink-700); }
.op-card .ds b { color: var(--ink-1000); }

/* ============================================================
   SVG diagram primitives — 노드/간선/박스 (08·10·11·22강 dg-* 재사용)
   ============================================================ */
.dg-line   { stroke: var(--ink-300); stroke-width: 2; }
.dg-line-y { stroke: var(--eduwill-yellow-600); stroke-width: 2.5; }
.dg-edge   { stroke: var(--ink-400); stroke-width: 2.5; }
.dg-edge-y { stroke: var(--eduwill-yellow-600); stroke-width: 3; }
.dg-cap    { fill: var(--ink-500); font: 700 12px var(--font-sans); text-anchor: middle; }

/* 트리/그래프 도식 프레임 */
.tree-frame {
  background: var(--ink-50);
  border: 1.5px solid var(--ink-200);
  border-radius: 12px;
  padding: 12px;
  display: grid;
  place-items: center;
}
.tree-frame.hi { background: var(--eduwill-yellow-50); border-color: var(--eduwill-yellow); }
.tree-frame svg { width: 100%; height: auto; max-height: 200px; display: block; }
.tree-frame .cap { margin-top: 6px; font-size: 12px; color: var(--ink-500); font-weight: 600; text-align: center; }

/* ---------- utility: small caption ---------- */
.cap { font-size: 12px; color: var(--ink-500); }

/* DRM/적층 도식 SVG primitives (22강 계승 — 본 데크에선 미사용이나 호환 유지) */
.dg-box   { fill: white; stroke: var(--ink-300); stroke-width: 2; rx: 8; }
.dg-box-d { fill: var(--ink-1000); stroke: var(--ink-1000); }
.dg-box-y { fill: var(--eduwill-yellow); stroke: var(--eduwill-yellow-600); }
.dg-bt    { fill: var(--ink-1000); font: 800 13px var(--font-sans); text-anchor: middle; dominant-baseline: central; }
.dg-bt-w  { fill: white; font: 800 13px var(--font-sans); text-anchor: middle; dominant-baseline: central; }
.dg-arr   { stroke: var(--ink-400); stroke-width: 2.5; fill: none; marker-end: url(#ah); }
.dg-arr-y { stroke: var(--eduwill-yellow-600); stroke-width: 3; fill: none; marker-end: url(#ahy); }
.dg-flab  { fill: var(--ink-500); font: 700 11px var(--font-sans); text-anchor: middle; }

/* ============================================================
   단계 카드 그리드 — 조인 종류 카드 등 (22강 step-grid 계승)
   ============================================================ */
.step-grid { display: grid; gap: 10px; }
.step-grid.c2 { grid-template-columns: 1fr 1fr; }
.step-grid.c3 { grid-template-columns: 1fr 1fr 1fr; }
.step-card {
  background: white;
  border: 1.5px solid var(--ink-200);
  border-radius: 12px;
  border-left: 5px solid var(--eduwill-yellow);
  padding: 12px 16px;
}
.step-card.gray { border-left-color: var(--ink-1000); }
.step-card.info { border-left-color: var(--info-500); }
.step-card .hd { display: flex; align-items: baseline; gap: 10px; }
.step-card .hd .nm { font: 800 16px/1 var(--font-sans); color: var(--ink-1000); }
.step-card .hd .badge2 { margin-left: auto; font: 800 13px/1 var(--font-mono); color: var(--eduwill-yellow-700); }
.step-card .bd { margin-top: 6px; font-size: 13px; line-height: 1.45; color: var(--ink-800); }
.step-card .bd b { color: var(--ink-1000); }

/* ============================================================
   comp-grid — 카드 그리드 (22강 계승, 본 데크 보조)
   ============================================================ */
.comp-grid { display: grid; grid-template-columns: 1fr 1fr 1fr; gap: 10px; }
.comp-card {
  background: white;
  border: 1.5px solid var(--ink-200);
  border-top: 5px solid var(--ink-1000);
  border-radius: 10px;
  padding: 11px 13px;
}
.comp-card.part { border-top-color: var(--eduwill-yellow); }
.comp-card .hd { display: flex; align-items: baseline; gap: 8px; }
.comp-card .ch { font: 800 22px/1 var(--font-sans); color: var(--eduwill-yellow-700); }
.comp-card .nm { font: 800 14.5px/1.15 var(--font-sans); color: var(--ink-1000); letter-spacing: -0.01em; }
.comp-card .ds { font-size: 11.5px; color: var(--ink-700); line-height: 1.4; margin-top: 6px; }
.comp-card .ds b { color: var(--ink-1000); }

/* ============================================================
   미니 테이블 페어 — σ/π 연산 before/after 결과표 (예제 슬라이드)
   ─ tbl.compact를 가로로 결합 + 가운데 연산 화살표
   ============================================================ */
.tbl-pair {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  gap: 12px;
  align-items: center;
}
.tbl-pair .op-arrow {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 3px;
  flex-shrink: 0;
}
.tbl-pair .op-arrow .glyph { font: 800 22px/1 var(--font-sans); color: var(--eduwill-yellow-700); }
.tbl-pair .op-arrow .lab { font-size: 10px; font-weight: 700; color: var(--ink-500); white-space: nowrap; }
.tbl-pair .mini-cap { font-size: 11px; font-weight: 700; color: var(--ink-500); margin-bottom: 4px; text-align: center; }
.mini-tbl { width: 100%; border-collapse: collapse; font-size: 12.5px; }
.mini-tbl thead th { background: var(--ink-1000); color: white; padding: 6px 8px; text-align: left; font-weight: 700; font-size: 11.5px; }
.mini-tbl tbody td { padding: 5px 8px; border-bottom: 1px solid var(--ink-200); color: var(--ink-900); }
.mini-tbl tbody tr:nth-child(even) td { background: var(--ink-50); }
.mini-tbl tbody tr.hi td { background: var(--eduwill-yellow-100); font-weight: 700; }
.mini-tbl tbody tr.drop td { color: var(--ink-400); text-decoration: line-through; }

/* ============================================================
   푸터 안전영역(y≤672) 압축 — 22강 검증값 계승
   _slide.css 코어보다 뒤에 로드되므로 이 데크에만 적용됨.
   ============================================================ */
.slide-content { gap: 22px; }

.def-box { grid-template-columns: 118px 1fr; }
.def-box .term { padding: 14px 10px; }
.def-box .term .abbr { font-size: 25px; letter-spacing: -0.02em; line-height: 1.05; }
.def-box .term .full { font-size: 10px; margin-top: 4px; line-height: 1.25; word-break: keep-all; }
.def-box .body { padding: 14px 20px; }
.def-box .body .label { font-size: 11px; }
.def-box .body .text { font-size: 15.5px; line-height: 1.45; margin-top: 4px; }

.metaphor { padding: 13px 18px; }
.metaphor .icon { width: 38px; height: 38px; font-size: 18px; }
.metaphor .text { font-size: 14.5px; line-height: 1.45; }

.pass-tip, .real, .callout.compact { padding: 12px 18px; }
.pass-tip .text, .real .text { font-size: 14.5px; line-height: 1.45; }
.mnemonic { padding: 13px 20px; }
.mnemonic .phrase { font-size: 18px; }

/* ---------- cmp-tbl 압축 변형 (다축 비교표 안전영역 보존) ---------- */
.cmp-tbl.compact { font-size: 13.5px; }
.cmp-tbl.compact thead th { padding: 8px 14px; font-size: 13px; }
.cmp-tbl.compact tbody td { padding: 7px 14px; }
.cmp-tbl.compact tbody td:first-child { width: 110px; }