/* ============================================================
   DB Study — 공통 스타일시트
   PostgreSQL · ClickHouse · Elasticsearch 학습 사이트
   ============================================================ */

:root {
  --bg: #0d1117;
  --bg-soft: #161b22;
  --bg-card: #1c2128;
  --bg-inset: #10151c;
  --border: #30363d;
  --border-soft: #21262d;
  --text: #e6edf3;
  --text-dim: #9aa7b3;
  --text-faint: #6e7a86;

  --pg: #336791;
  --pg-soft: #4c8ec4;
  --ch: #f2c744;
  --ch-soft: #ffdd66;
  --es: #10b981;
  --es-soft: #34d399;
  --or: #c74634;
  --or-soft: #e2705a;

  --accent: #58a6ff;
  --accent-soft: rgba(88, 166, 255, .12);
  --ok: #3fb950;
  --warn: #d29922;
  --danger: #f85149;
  --purple: #bc8cff;

  --radius: 12px;
  --radius-sm: 8px;
  --sidebar-w: 280px;
  --font-mono: "SF Mono", "JetBrains Mono", Consolas, "Nanum Gothic Coding", monospace;
  --shadow: 0 8px 30px rgba(0, 0, 0, .35);
}

html[data-theme="light"] {
  --bg: #f6f8fa;
  --bg-soft: #ffffff;
  --bg-card: #ffffff;
  --bg-inset: #eef1f5;
  --border: #d0d7de;
  --border-soft: #e4e9ee;
  --text: #1f2328;
  --text-dim: #57606a;
  --text-faint: #848d97;
  --accent: #0969da;
  --accent-soft: rgba(9, 105, 218, .08);
  --ok: #1a7f37;
  --warn: #9a6700;
  --danger: #cf222e;
  --purple: #8250df;
  --shadow: 0 8px 30px rgba(31, 35, 40, .10);
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: "Pretendard", "Apple SD Gothic Neo", "Noto Sans KR", "Malgun Gothic", system-ui, sans-serif;
  font-size: 16px;
  line-height: 1.75;
  -webkit-font-smoothing: antialiased;
}

a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }

/* ---------- 상단 바 ---------- */
.topbar {
  position: sticky;
  top: 0;
  z-index: 50;
  display: flex;
  align-items: center;
  gap: 14px;
  padding: 0 20px;
  height: 56px;
  background: color-mix(in srgb, var(--bg) 82%, transparent);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--border-soft);
}
.topbar .brand {
  font-weight: 800;
  font-size: 16px;
  color: var(--text);
  display: flex;
  align-items: center;
  gap: 8px;
  white-space: nowrap;
}
.topbar .brand:hover { text-decoration: none; }
.topbar .brand .logo { font-size: 20px; }
.topbar .db-switch {
  display: flex;
  gap: 6px;
  margin-left: 8px;
}
.topbar .db-switch a {
  padding: 5px 12px;
  border-radius: 999px;
  font-size: 13px;
  font-weight: 600;
  color: var(--text-dim);
  border: 1px solid transparent;
}
.topbar .db-switch a:hover { text-decoration: none; color: var(--text); background: var(--bg-card); }
.topbar .db-switch a.on-pg { color: #fff; background: var(--pg); }
.topbar .db-switch a.on-ch { color: #1f2328; background: var(--ch); }
.topbar .db-switch a.on-es { color: #fff; background: var(--es); }
.topbar .db-switch a.on-or { color: #fff; background: var(--or); }
.topbar .spacer { flex: 1; }
.topbar button {
  background: none;
  border: 1px solid var(--border);
  color: var(--text-dim);
  border-radius: var(--radius-sm);
  padding: 5px 10px;
  cursor: pointer;
  font-size: 14px;
}
.topbar button:hover { color: var(--text); background: var(--bg-card); }
#nav-toggle { display: none; }

/* ---------- 레이아웃 ---------- */
.layout {
  display: flex;
  max-width: 1480px;
  margin: 0 auto;
}

.sidebar {
  width: var(--sidebar-w);
  flex: none;
  position: sticky;
  top: 56px;
  height: calc(100vh - 56px);
  overflow-y: auto;
  padding: 20px 12px 40px;
  border-right: 1px solid var(--border-soft);
  scrollbar-width: thin;
}
.sidebar .group-title {
  font-size: 11px;
  font-weight: 700;
  letter-spacing: .08em;
  text-transform: uppercase;
  color: var(--text-faint);
  margin: 18px 10px 6px;
}
.sidebar a.chap {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 6px 10px;
  border-radius: var(--radius-sm);
  color: var(--text-dim);
  font-size: 13.5px;
  line-height: 1.4;
}
.sidebar a.chap:hover { background: var(--bg-card); color: var(--text); text-decoration: none; }
.sidebar a.chap.active {
  background: var(--accent-soft);
  color: var(--accent);
  font-weight: 700;
}
.sidebar a.chap .num {
  flex: none;
  width: 24px;
  height: 24px;
  border-radius: 6px;
  background: var(--bg-inset);
  border: 1px solid var(--border-soft);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  font-size: 11px;
  font-weight: 700;
  font-family: var(--font-mono);
}
.sidebar a.chap.done .num { background: var(--ok); border-color: var(--ok); color: #fff; }
.sidebar a.chap.active .num { border-color: var(--accent); color: var(--accent); }

main.content {
  flex: 1;
  min-width: 0;
  padding: 36px 48px 120px;
  max-width: 940px;
}

/* ---------- 타이포그래피 ---------- */
h1 { font-size: 32px; line-height: 1.3; margin: 8px 0 6px; letter-spacing: -.02em; }
h2 {
  font-size: 23px;
  margin: 56px 0 14px;
  padding-top: 18px;
  border-top: 1px solid var(--border-soft);
  letter-spacing: -.01em;
}
h2:first-of-type { border-top: none; margin-top: 28px; }
h3 { font-size: 18px; margin: 34px 0 10px; }
p { margin: 12px 0; }
.lead { font-size: 17.5px; color: var(--text-dim); margin-bottom: 8px; }
strong { color: var(--text); }
ul, ol { padding-left: 24px; }
li { margin: 5px 0; }
hr { border: none; border-top: 1px solid var(--border-soft); margin: 40px 0; }

.chapter-meta {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
  margin: 14px 0 24px;
}
.tag {
  font-size: 12px;
  font-weight: 600;
  padding: 3px 10px;
  border-radius: 999px;
  border: 1px solid var(--border);
  color: var(--text-dim);
  background: var(--bg-card);
}
.tag.lv-basic { color: var(--ok); border-color: color-mix(in srgb, var(--ok) 40%, transparent); }
.tag.lv-mid { color: var(--warn); border-color: color-mix(in srgb, var(--warn) 40%, transparent); }
.tag.lv-adv { color: var(--danger); border-color: color-mix(in srgb, var(--danger) 40%, transparent); }

/* ---------- 코드 ---------- */
pre {
  position: relative;
  background: var(--bg-inset);
  border: 1px solid var(--border-soft);
  border-radius: var(--radius);
  padding: 16px 18px;
  overflow-x: auto;
  font-size: 13.5px;
  line-height: 1.65;
  margin: 16px 0;
}
code { font-family: var(--font-mono); }
p code, li code, td code, h2 code, h3 code {
  background: var(--bg-inset);
  border: 1px solid var(--border-soft);
  border-radius: 5px;
  padding: 1.5px 6px;
  font-size: .88em;
  color: var(--accent);
  white-space: nowrap;
}
pre .copy-btn {
  position: absolute;
  top: 8px;
  right: 8px;
  font-size: 11px;
  padding: 3px 9px;
  border-radius: 6px;
  border: 1px solid var(--border);
  background: var(--bg-card);
  color: var(--text-dim);
  cursor: pointer;
  opacity: 0;
  transition: opacity .15s;
}
pre:hover .copy-btn { opacity: 1; }
pre .copy-btn:hover { color: var(--text); }

/* 코드 하이라이트 (수동 span) */
.k  { color: #ff7b72; }              /* keyword */
.s  { color: #a5d6ff; }              /* string */
.n  { color: #79c0ff; }              /* number */
.c  { color: var(--text-faint); font-style: italic; } /* comment */
.f  { color: #d2a8ff; }              /* function */
html[data-theme="light"] .k { color: #cf222e; }
html[data-theme="light"] .s { color: #0a3069; }
html[data-theme="light"] .n { color: #0550ae; }
html[data-theme="light"] .f { color: #8250df; }

/* ---------- 표 ---------- */
.table-wrap { overflow-x: auto; margin: 16px 0; border-radius: var(--radius); border: 1px solid var(--border-soft); }
table { border-collapse: collapse; width: 100%; font-size: 14px; }
th, td { padding: 9px 14px; border-bottom: 1px solid var(--border-soft); text-align: left; vertical-align: top; }
th { background: var(--bg-inset); font-size: 13px; white-space: nowrap; }
tr:last-child td { border-bottom: none; }

/* ---------- 콜아웃 ---------- */
.callout {
  display: flex;
  gap: 12px;
  padding: 14px 16px;
  border-radius: var(--radius);
  border: 1px solid var(--border-soft);
  background: var(--bg-card);
  margin: 18px 0;
  font-size: 15px;
}
.callout .ico { flex: none; font-size: 18px; line-height: 1.5; }
.callout p { margin: 4px 0; }
.callout.tip { border-left: 4px solid var(--ok); }
.callout.info { border-left: 4px solid var(--accent); }
.callout.warn { border-left: 4px solid var(--warn); }
.callout.danger { border-left: 4px solid var(--danger); }
.callout .callout-title { font-weight: 700; font-size: 14px; }

/* ---------- 애니메이션 씬 (핵심 컴포넌트) ---------- */
.anim {
  margin: 26px 0;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--bg-card);
  overflow: hidden;
  box-shadow: var(--shadow);
}
.anim .anim-head {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 10px 16px;
  border-bottom: 1px solid var(--border-soft);
  background: var(--bg-inset);
}
.anim .anim-head .dot { width: 9px; height: 9px; border-radius: 50%; background: var(--accent); animation: pulse 2s infinite; }
.anim .anim-head .anim-title { font-size: 13.5px; font-weight: 700; color: var(--text-dim); }
.anim .anim-stage { padding: 18px; background: var(--bg-soft); }
.anim svg { display: block; width: 100%; height: auto; }

.anim .anim-caption {
  min-height: 52px;
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 10px 16px;
  font-size: 14.5px;
  border-top: 1px solid var(--border-soft);
  background: var(--bg-card);
  color: var(--text);
}
.anim .anim-caption .step-badge {
  flex: none;
  font-family: var(--font-mono);
  font-size: 11px;
  font-weight: 700;
  background: var(--accent-soft);
  color: var(--accent);
  border-radius: 6px;
  padding: 2px 8px;
}
.anim .anim-controls {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 10px 14px;
  border-top: 1px solid var(--border-soft);
  background: var(--bg-inset);
}
.anim .anim-controls button {
  border: 1px solid var(--border);
  background: var(--bg-card);
  color: var(--text);
  border-radius: 8px;
  padding: 6px 13px;
  font-size: 13px;
  font-weight: 600;
  cursor: pointer;
  transition: background .15s, transform .1s;
}
.anim .anim-controls button:hover { background: var(--bg-soft); }
.anim .anim-controls button:active { transform: scale(.96); }
.anim .anim-controls button.play-btn {
  background: var(--accent);
  border-color: var(--accent);
  color: #fff;
  min-width: 84px;
}
.anim .anim-controls .anim-progress {
  flex: 1;
  height: 5px;
  border-radius: 99px;
  background: var(--border-soft);
  overflow: hidden;
}
.anim .anim-controls .anim-progress > i {
  display: block;
  height: 100%;
  width: 0%;
  background: var(--accent);
  border-radius: 99px;
  transition: width .35s ease;
}

/* 스텝 표시/숨김: data-show="N" → step >= N 부터 보임, data-show="N-M" → 구간만 */
.anim [data-show] { opacity: 0; transition: opacity .5s ease, transform .5s ease; }
.anim [data-show].shown { opacity: 1; }
.anim [data-hide].hidden-step { opacity: 0 !important; }
.anim [data-active] { transition: all .4s ease; }
.anim .rise { transform: translateY(8px); }
.anim .rise.shown { transform: translateY(0); }

/* SVG 공통 클래스 */
.sv-box { fill: var(--bg-inset); stroke: var(--border); stroke-width: 1.4; rx: 8; }
.sv-box-accent { fill: var(--accent-soft); stroke: var(--accent); stroke-width: 1.6; }
.sv-label { fill: var(--text); font-size: 13px; font-weight: 600; font-family: inherit; }
.sv-label-sm { fill: var(--text-dim); font-size: 11px; font-family: inherit; }
.sv-mono { font-family: var(--font-mono); }
.sv-line { stroke: var(--text-faint); stroke-width: 1.6; fill: none; }
.sv-arrow { stroke: var(--accent); stroke-width: 2; fill: none; }
.sv-dim { opacity: .35; }

/* 흐르는 점 애니메이션 */
@keyframes flowdash { to { stroke-dashoffset: -24; } }
.flow-line {
  stroke-dasharray: 6 6;
  animation: flowdash 1s linear infinite;
}
@keyframes pulse {
  0%, 100% { opacity: 1; }
  50% { opacity: .35; }
}
.pulse { animation: pulse 1.6s ease-in-out infinite; }
@keyframes blink-fill {
  0%, 100% { fill-opacity: .15; }
  50% { fill-opacity: .55; }
}
.blink { animation: blink-fill 1.4s ease-in-out infinite; }
@keyframes floaty {
  0%, 100% { transform: translateY(0); }
  50% { transform: translateY(-5px); }
}

/* ---------- 다이어그램(정적) ---------- */
.diagram {
  margin: 20px 0;
  padding: 18px;
  border: 1px solid var(--border-soft);
  border-radius: var(--radius);
  background: var(--bg-card);
}
.diagram svg { display: block; width: 100%; height: auto; }
.diagram .diagram-caption {
  text-align: center;
  font-size: 13px;
  color: var(--text-faint);
  margin-top: 10px;
}

/* ---------- 퀴즈 ---------- */
.quiz {
  margin: 22px 0;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
}
.quiz .quiz-q {
  padding: 14px 18px;
  background: var(--bg-card);
  font-weight: 600;
  display: flex;
  gap: 10px;
}
.quiz .quiz-q::before { content: "❓"; }
.quiz .quiz-opts { padding: 6px 14px 14px; background: var(--bg-card); display: grid; gap: 8px; }
.quiz .quiz-opts button {
  text-align: left;
  padding: 10px 14px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border-soft);
  background: var(--bg-inset);
  color: var(--text);
  font-size: 14.5px;
  cursor: pointer;
  transition: border-color .15s;
}
.quiz .quiz-opts button:hover { border-color: var(--accent); }
.quiz .quiz-opts button.correct { border-color: var(--ok); background: color-mix(in srgb, var(--ok) 12%, var(--bg-inset)); }
.quiz .quiz-opts button.wrong { border-color: var(--danger); background: color-mix(in srgb, var(--danger) 10%, var(--bg-inset)); }
.quiz .quiz-expl {
  display: none;
  padding: 13px 18px;
  border-top: 1px solid var(--border-soft);
  background: var(--bg-inset);
  font-size: 14px;
  color: var(--text-dim);
}
.quiz.answered .quiz-expl { display: block; }

/* ---------- 카드 그리드 ---------- */
.grid { display: grid; gap: 16px; margin: 20px 0; }
.grid.g2 { grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); }
.grid.g3 { grid-template-columns: repeat(auto-fit, minmax(220px, 1fr)); }
.card {
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--bg-card);
  padding: 18px 20px;
}
.card h4 { margin: 0 0 8px; font-size: 15.5px; }
.card p { margin: 6px 0 0; font-size: 14px; color: var(--text-dim); }

/* ---------- 챕터 하단 네비 ---------- */
.chapter-nav {
  display: flex;
  justify-content: space-between;
  gap: 14px;
  margin-top: 70px;
  padding-top: 24px;
  border-top: 1px solid var(--border-soft);
}
.chapter-nav a {
  flex: 1;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 14px 18px;
  background: var(--bg-card);
}
.chapter-nav a:hover { border-color: var(--accent); text-decoration: none; }
.chapter-nav a .dir { font-size: 12px; color: var(--text-faint); }
.chapter-nav a .title { font-weight: 700; font-size: 15px; color: var(--text); }
.chapter-nav a.next { text-align: right; }
.chapter-nav .done-btn {
  flex: none;
  align-self: center;
  border: 1px solid var(--ok);
  color: var(--ok);
  background: none;
  border-radius: var(--radius);
  padding: 12px 18px;
  font-size: 14px;
  font-weight: 700;
  cursor: pointer;
}
.chapter-nav .done-btn.done { background: var(--ok); color: #fff; }

/* ---------- 홈(허브) 전용 ---------- */
.hero {
  text-align: center;
  padding: 76px 24px 40px;
  max-width: 860px;
  margin: 0 auto;
}
.hero h1 { font-size: clamp(30px, 5vw, 48px); margin-bottom: 14px; }
.hero .hero-sub { font-size: 18px; color: var(--text-dim); max-width: 640px; margin: 0 auto; }
.hero .hero-badges { display: flex; gap: 10px; justify-content: center; margin-top: 22px; flex-wrap: wrap; }

.db-cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(290px, 1fr));
  gap: 22px;
  max-width: 1150px;
  margin: 30px auto 60px;
  padding: 0 24px;
}
.db-card {
  display: block;
  border: 1px solid var(--border);
  border-radius: 18px;
  background: var(--bg-card);
  padding: 28px;
  color: var(--text);
  transition: transform .2s ease, border-color .2s ease, box-shadow .2s ease;
  position: relative;
  overflow: hidden;
}
.db-card:hover { transform: translateY(-5px); text-decoration: none; box-shadow: var(--shadow); }
.db-card.pg:hover { border-color: var(--pg-soft); }
.db-card.ch:hover { border-color: var(--ch); }
.db-card.es:hover { border-color: var(--es); }
.db-card.or:hover { border-color: var(--or-soft); }
.db-card .db-ico { font-size: 40px; margin-bottom: 10px; display: block; animation: floaty 3.4s ease-in-out infinite; }
.db-card h2 { border: none; margin: 0 0 6px; padding: 0; font-size: 22px; }
.db-card .db-desc { color: var(--text-dim); font-size: 14.5px; min-height: 66px; }
.db-card .db-stats { display: flex; gap: 8px; margin-top: 16px; flex-wrap: wrap; }
.db-card .bar { height: 4px; border-radius: 99px; margin-top: 20px; }
.db-card.pg .bar { background: linear-gradient(90deg, var(--pg), var(--pg-soft)); }
.db-card.ch .bar { background: linear-gradient(90deg, #d9a514, var(--ch)); }
.db-card.es .bar { background: linear-gradient(90deg, #0b8a61, var(--es)); }
.db-card.or .bar { background: linear-gradient(90deg, #96352a, var(--or-soft)); }

.home-section { max-width: 1150px; margin: 0 auto 70px; padding: 0 24px; }
.home-section > h2 { border: none; text-align: center; font-size: 26px; margin-bottom: 8px; }
.home-section > .sec-sub { text-align: center; color: var(--text-dim); margin: 0 0 28px; }

footer.site-footer {
  border-top: 1px solid var(--border-soft);
  padding: 30px 24px 50px;
  text-align: center;
  color: var(--text-faint);
  font-size: 13.5px;
}

/* ---------- 반응형 ---------- */
@media (max-width: 960px) {
  #nav-toggle { display: inline-block; }
  .sidebar {
    position: fixed;
    left: 0;
    top: 56px;
    background: var(--bg);
    z-index: 40;
    transform: translateX(-100%);
    transition: transform .25s ease;
    box-shadow: var(--shadow);
  }
  body.nav-open .sidebar { transform: translateX(0); }
  main.content { padding: 26px 20px 90px; }
  .topbar .db-switch { display: none; }
  h1 { font-size: 26px; }
}