/* ===================================================================
   个性化旅游系统 — 项目展示页样式
   Material Design 风格，朴素淡雅色调
   =================================================================== */

/* ── CSS Custom Properties ── */
:root {
  /* Color palette: Blue Grey family */
  --clr-hero-bg:    #263238;
  --clr-hero-text:  #ECEFF1;
  --clr-hero-muted: #90A4AE;

  --clr-bg:         #F8F9FA;
  --clr-surface:    #FFFFFF;
  --clr-border:     #ECEFF1;
  --clr-divider:    #CFD8DC;

  --clr-primary:    #455A64;
  --clr-primary-dk: #37474F;
  --clr-primary-lt: #B0BEC5;

  --clr-accent:     #00796B;
  --clr-accent-lt:  #B2DFDB;

  --clr-text:       #263238;
  --clr-text-2:     #546E7A;
  --clr-text-3:     #90A4AE;

  /* Elevation shadows */
  --shadow-1: 0 1px 3px rgba(0,0,0,.08), 0 1px 2px rgba(0,0,0,.06);
  --shadow-2: 0 3px 6px rgba(0,0,0,.08), 0 2px 4px rgba(0,0,0,.06);
  --shadow-3: 0 8px 24px rgba(0,0,0,.08), 0 4px 8px rgba(0,0,0,.04);

  /* Typography */
  --font-sans: 'Inter', 'Noto Sans SC', system-ui, sans-serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', monospace;

  /* Spacing */
  --section-pad: 88px;
  --container-w: 1160px;

  /* Transitions */
  --ease: cubic-bezier(.4, 0, .2, 1);
  --dur: 200ms;
}

/* ── Reset ── */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

html {
  scroll-behavior: smooth;
  font-size: 16px;
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: var(--font-sans);
  background: var(--clr-bg);
  color: var(--clr-text);
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
}

img, svg { display: block; max-width: 100%; }
a { color: inherit; text-decoration: none; }
ul, ol { list-style: none; }
button { cursor: pointer; font-family: inherit; border: none; background: none; }

/* ── Container ── */
.container {
  width: 100%;
  max-width: var(--container-w);
  margin: 0 auto;
  padding: 0 24px;
}

/* ── Navigation ── */
.nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  background: rgba(38, 50, 56, .95);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid rgba(255,255,255,.06);
  transition: box-shadow var(--dur) var(--ease);
}
.nav.scrolled { box-shadow: var(--shadow-2); }

.nav__container {
  max-width: var(--container-w);
  margin: 0 auto;
  padding: 0 24px;
  height: 56px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
}

.nav__brand {
  display: flex;
  align-items: center;
  gap: 10px;
  flex-shrink: 0;
}
.nav__icon { width: 20px; height: 20px; color: var(--clr-hero-muted); }
.nav__title {
  font-size: .9rem;
  font-weight: 600;
  color: var(--clr-hero-text);
  letter-spacing: .02em;
}
.nav__badge {
  font-size: .7rem;
  font-weight: 500;
  color: var(--clr-hero-muted);
  background: rgba(255,255,255,.08);
  padding: 2px 8px;
  border-radius: 20px;
}

.nav__links {
  display: flex;
  align-items: center;
  gap: 4px;
}
.nav__link {
  font-size: .82rem;
  font-weight: 500;
  color: var(--clr-hero-muted);
  padding: 6px 12px;
  border-radius: 6px;
  transition: color var(--dur) var(--ease), background var(--dur) var(--ease);
}
.nav__link:hover, .nav__link.active {
  color: var(--clr-hero-text);
  background: rgba(255,255,255,.08);
}

/* ── Hero ── */
.hero {
  min-height: 100vh;
  background: var(--clr-hero-bg);
  display: flex;
  justify-content: center;
  align-items: center;
}

.hero__inner {
  width: 100%;
  max-width: var(--container-w);
  display: flex;
  align-items: center;
  gap: 48px;
  padding: 100px 24px 80px;
}

.hero__content { flex: 1; max-width: 560px; }

.hero__eyebrow { margin-bottom: 20px; }
.hero__tag {
  display: inline-block;
  font-size: .75rem;
  font-weight: 500;
  letter-spacing: .08em;
  text-transform: uppercase;
  color: var(--clr-accent-lt);
  background: rgba(0,121,107,.15);
  border: 1px solid rgba(0,121,107,.3);
  padding: 5px 14px;
  border-radius: 20px;
}

.hero__title {
  font-size: clamp(2rem, 5vw, 3.2rem);
  font-weight: 700;
  color: var(--clr-hero-text);
  line-height: 1.2;
  letter-spacing: -.02em;
  margin-bottom: 20px;
}

.hero__desc {
  font-size: 1.05rem;
  color: var(--clr-hero-muted);
  line-height: 1.8;
  margin-bottom: 36px;
}

.hero__team {
  display: flex;
  align-items: center;
  gap: 16px;
  margin-bottom: 28px;
}
.hero__member {
  display: flex;
  align-items: center;
  gap: 10px;
  color: var(--clr-hero-muted);
  font-size: .9rem;
}
.hero__avatar {
  width: 36px;
  height: 36px;
  border-radius: 50%;
  background: rgba(255,255,255,.12);
  border: 1px solid rgba(255,255,255,.16);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: .8rem;
  font-weight: 600;
  color: var(--clr-hero-text);
}
.hero__sep {
  width: 1px;
  height: 24px;
  background: rgba(255,255,255,.15);
}

.hero__stack {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}
.stack-badge {
  font-size: .75rem;
  font-weight: 500;
  font-family: var(--font-mono);
  color: var(--clr-hero-muted);
  background: rgba(255,255,255,.07);
  border: 1px solid rgba(255,255,255,.1);
  padding: 4px 12px;
  border-radius: 6px;
}

.hero__visual {
  flex: 1;
  max-width: 420px;
  display: flex;
  align-items: center;
  justify-content: center;
}

.hero__qr {
  display: flex;
  align-items: center;
  gap: 14px;
  margin-top: 28px;
  padding-top: 24px;
  border-top: 1px solid rgba(255,255,255,.08);
}
.hero__qr-img {
  border-radius: 6px;
  flex-shrink: 0;
}
.hero__qr-info {
  display: flex;
  flex-direction: column;
  gap: 4px;
}
.hero__qr-url {
  font-size: .82rem;
  font-weight: 600;
  font-family: var(--font-mono);
  color: var(--clr-hero-text);
}
.hero__qr-hint {
  font-size: .72rem;
  color: var(--clr-hero-muted);
}
.hero__graph {
  width: 100%;
  opacity: .9;
}

/* ── Sections ── */
.section {
  padding: var(--section-pad) 0;
  background: var(--clr-bg);
}
.section--alt { background: var(--clr-surface); }

.section-head {
  text-align: center;
  margin-bottom: 56px;
}
.section__title {
  font-size: clamp(1.5rem, 3vw, 2.1rem);
  font-weight: 700;
  color: var(--clr-text);
  letter-spacing: -.02em;
  margin-bottom: 12px;
}
.section__sub {
  font-size: 1rem;
  color: var(--clr-text-2);
  max-width: 540px;
  margin: 0 auto;
}

/* ── Scroll Reveal ── */
.reveal {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity .55s var(--ease), transform .55s var(--ease);
  transition-delay: var(--delay, 0ms);
}
.reveal.visible { opacity: 1; transform: none; }

/* ── Features Grid ── */
.features-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
}

.feat-card {
  background: var(--clr-surface);
  border: 1px solid var(--clr-border);
  border-radius: 12px;
  padding: 28px 24px;
  position: relative;
  transition: box-shadow var(--dur) var(--ease), transform var(--dur) var(--ease);
}
.feat-card:hover {
  box-shadow: var(--shadow-2);
  transform: translateY(-2px);
}
.feat-card__num {
  position: absolute;
  top: 20px;
  right: 20px;
  font-size: .7rem;
  font-weight: 700;
  font-family: var(--font-mono);
  color: var(--clr-text-3);
  letter-spacing: .06em;
}
.feat-card__icon {
  width: 44px;
  height: 44px;
  background: var(--clr-bg);
  border: 1px solid var(--clr-border);
  border-radius: 10px;
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 16px;
}
.feat-card__icon svg {
  width: 20px;
  height: 20px;
  stroke: var(--clr-primary);
}
.feat-card h3 {
  font-size: 1rem;
  font-weight: 600;
  color: var(--clr-text);
  margin-bottom: 8px;
}
.feat-card p {
  font-size: .875rem;
  color: var(--clr-text-2);
  line-height: 1.65;
}

/* ── Architecture ── */
.arch-wrap {
  display: grid;
  grid-template-columns: 1fr 220px;
  gap: 48px;
  align-items: start;
}

.arch-diagram { display: flex; flex-direction: column; gap: 0; }

.arch-layer {
  background: var(--clr-bg);
  border: 1px solid var(--clr-border);
  border-radius: 10px;
  padding: 16px 20px;
  transition: box-shadow var(--dur) var(--ease);
}
.arch-layer:hover { box-shadow: var(--shadow-1); }
.arch-layer--highlight {
  background: #ECEFF1;
  border-color: var(--clr-primary);
  border-width: 1.5px;
}

.arch-layer__label {
  font-size: .75rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: .08em;
  color: var(--clr-primary);
  margin-bottom: 10px;
  display: flex;
  align-items: center;
  gap: 8px;
}
.arch-layer__badge {
  font-size: .65rem;
  background: var(--clr-primary);
  color: #fff;
  padding: 2px 8px;
  border-radius: 20px;
  text-transform: none;
  letter-spacing: 0;
}

.arch-layer__items { display: flex; flex-wrap: wrap; gap: 8px; }
.arch-chip {
  font-size: .8rem;
  color: var(--clr-text-2);
  background: var(--clr-surface);
  border: 1px solid var(--clr-border);
  padding: 4px 12px;
  border-radius: 20px;
}
.arch-chip--accent {
  color: var(--clr-accent);
  background: rgba(0,121,107,.05);
  border-color: rgba(0,121,107,.2);
  font-weight: 500;
}

.arch-connector {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 4px 20px;
}
.arch-connector__line {
  flex: 1;
  height: 1px;
  background: var(--clr-border);
}
.arch-connector__label {
  font-size: .7rem;
  color: var(--clr-text-3);
  white-space: nowrap;
}

.arch-stats {
  display: flex;
  flex-direction: column;
  gap: 16px;
  padding-top: 8px;
}
.arch-stat {
  background: var(--clr-bg);
  border: 1px solid var(--clr-border);
  border-radius: 10px;
  padding: 18px 20px;
  text-align: center;
}
.arch-stat__value {
  font-size: 1.8rem;
  font-weight: 700;
  color: var(--clr-primary);
  font-family: var(--font-mono);
  line-height: 1;
  margin-bottom: 6px;
}
.arch-stat__label {
  font-size: .78rem;
  color: var(--clr-text-2);
}

/* ── Data Structures Tabs ── */
.ds-panel {
  background: var(--clr-surface);
  border: 1px solid var(--clr-border);
  border-radius: 12px;
  overflow: hidden;
  box-shadow: var(--shadow-1);
}

.tab-bar {
  display: flex;
  background: var(--clr-bg);
  border-bottom: 1px solid var(--clr-border);
  padding: 0 4px;
}
.tab-btn {
  padding: 14px 20px;
  font-size: .875rem;
  font-weight: 500;
  color: var(--clr-text-2);
  border-bottom: 2px solid transparent;
  transition: color var(--dur) var(--ease), border-color var(--dur) var(--ease);
  white-space: nowrap;
  margin-bottom: -1px;
}
.tab-btn:hover { color: var(--clr-text); }
.tab-btn.active {
  color: var(--clr-primary);
  border-bottom-color: var(--clr-primary);
  background: var(--clr-surface);
}

.tab-pane { display: none; padding: 32px; }
.tab-pane.active { display: block; }

.ds-split {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 40px;
  align-items: start;
}

.ds-info h3 {
  font-size: 1.15rem;
  font-weight: 700;
  color: var(--clr-text);
  font-family: var(--font-mono);
  margin-bottom: 10px;
}
.ds-desc {
  font-size: .88rem;
  color: var(--clr-text-2);
  line-height: 1.7;
  margin-bottom: 18px;
}

.ds-meta {
  display: grid;
  grid-template-columns: auto 1fr;
  gap: 8px 16px;
  margin-bottom: 20px;
  font-size: .82rem;
}
.ds-meta dt {
  color: var(--clr-text-3);
  font-weight: 600;
  white-space: nowrap;
}
.ds-meta dd { color: var(--clr-text-2); }

/* ── Code Block ── */
.code-block {
  background: #263238;
  border-radius: 8px;
  overflow: hidden;
  font-family: var(--font-mono);
  font-size: .78rem;
  line-height: 1.7;
}
.code-block__header {
  background: rgba(255,255,255,.06);
  padding: 8px 16px;
  font-size: .72rem;
  color: #90A4AE;
  border-bottom: 1px solid rgba(255,255,255,.06);
}
.code-block pre { padding: 16px; overflow-x: auto; }
.code-block code { color: #B0BEC5; }

/* ── Viz Box ── */
.viz-box {
  display: flex;
  flex-direction: column;
  gap: 16px;
}
.viz-svg { width: 100%; border: 1px solid var(--clr-border); border-radius: 8px; background: var(--clr-bg); }
.viz-controls { display: flex; gap: 8px; flex-wrap: wrap; }
.viz-hint {
  font-size: .78rem;
  color: var(--clr-text-3);
  text-align: center;
  padding: 6px;
}
.viz-caption {
  font-size: .78rem;
  color: var(--clr-text-3);
  text-align: center;
}

/* ── Buttons ── */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  padding: 8px 18px;
  border-radius: 6px;
  font-size: .82rem;
  font-weight: 500;
  line-height: 1;
  transition: background var(--dur) var(--ease), opacity var(--dur) var(--ease);
}
.btn--primary {
  background: var(--clr-primary);
  color: #fff;
}
.btn--primary:hover { background: var(--clr-primary-dk); }
.btn--secondary {
  background: var(--clr-bg);
  color: var(--clr-primary);
  border: 1px solid var(--clr-primary-lt);
}
.btn--secondary:hover { background: var(--clr-border); }
.btn--ghost {
  background: transparent;
  color: var(--clr-text-2);
  border: 1px solid var(--clr-border);
}
.btn--ghost:hover { background: var(--clr-bg); }
.btn:disabled { opacity: .4; cursor: not-allowed; }

/* ── Inverted Index Viz ── */
.inverted-demo {
  font-family: var(--font-mono);
  font-size: .78rem;
  display: flex;
  flex-direction: column;
  gap: 12px;
  padding: 16px;
  background: var(--clr-bg);
  border: 1px solid var(--clr-border);
  border-radius: 8px;
  min-height: 200px;
}

.inv-query {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-bottom: 4px;
}
.inv-query-label { color: var(--clr-text-3); font-size: .72rem; }
.inv-query-term {
  background: var(--clr-primary);
  color: #fff;
  padding: 3px 10px;
  border-radius: 4px;
  font-weight: 600;
}

.inv-row {
  display: flex;
  align-items: center;
  gap: 10px;
}
.inv-gram {
  background: var(--clr-surface);
  border: 1px solid var(--clr-border);
  padding: 4px 10px;
  border-radius: 4px;
  color: var(--clr-text);
  min-width: 60px;
  text-align: center;
}
.inv-arrow { color: var(--clr-text-3); }
.inv-posting {
  display: flex;
  gap: 6px;
  flex-wrap: wrap;
}
.inv-doc {
  background: var(--clr-accent-lt);
  color: var(--clr-accent);
  padding: 2px 8px;
  border-radius: 4px;
  font-size: .72rem;
  font-weight: 600;
}

.inv-score-section { margin-top: 8px; border-top: 1px solid var(--clr-border); padding-top: 10px; }
.inv-score-title { color: var(--clr-text-3); font-size: .7rem; margin-bottom: 8px; }
.inv-score-row {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-bottom: 4px;
}
.inv-score-bar-wrap {
  flex: 1;
  height: 6px;
  background: var(--clr-border);
  border-radius: 3px;
  overflow: hidden;
}
.inv-score-bar {
  height: 100%;
  background: var(--clr-primary);
  border-radius: 3px;
  transition: width .6s var(--ease);
}
.inv-score-val { color: var(--clr-text-2); min-width: 36px; text-align: right; font-size: .72rem; }

/* ── Algorithm Cards ── */
.algo-card {
  background: var(--clr-surface);
  border: 1px solid var(--clr-border);
  border-radius: 12px;
  overflow: hidden;
  box-shadow: var(--shadow-1);
  margin-bottom: 28px;
}
.algo-card__hd {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 20px;
  padding: 24px 28px;
  border-bottom: 1px solid var(--clr-border);
}
.algo-card__info h3 {
  font-size: 1.05rem;
  font-weight: 700;
  color: var(--clr-text);
  margin-bottom: 6px;
}
.algo-card__info p {
  font-size: .85rem;
  color: var(--clr-text-2);
  line-height: 1.6;
}
.algo-complexity {
  display: flex;
  gap: 16px;
  margin-top: 8px;
}
.algo-complexity span {
  font-size: .75rem;
  font-family: var(--font-mono);
  color: var(--clr-accent);
  background: rgba(0,121,107,.06);
  border: 1px solid rgba(0,121,107,.15);
  padding: 2px 10px;
  border-radius: 4px;
}
.algo-controls {
  display: flex;
  gap: 8px;
  flex-shrink: 0;
}
.algo-card__bd { padding: 24px 28px; }

/* ── Dijkstra layout ── */
.dijkstra-layout {
  display: grid;
  grid-template-columns: 1fr 340px;
  gap: 24px;
  align-items: start;
}
.dijk-svg { border-radius: 8px; }

.dijk-info-wrap { display: flex; flex-direction: column; gap: 16px; }

.dijk-status-box {
  display: flex;
  align-items: center;
  gap: 10px;
  background: var(--clr-bg);
  border: 1px solid var(--clr-border);
  border-radius: 8px;
  padding: 12px 16px;
  font-size: .82rem;
  color: var(--clr-text-2);
  min-height: 48px;
}
.dijk-status-icon { color: var(--clr-text-3); font-size: .6rem; }

.dist-table {
  width: 100%;
  border-collapse: collapse;
  font-size: .75rem;
  font-family: var(--font-mono);
}
.dist-table th, .dist-table td {
  padding: 6px 8px;
  text-align: center;
  border: 1px solid var(--clr-border);
}
.dist-table th { background: var(--clr-bg); color: var(--clr-text-2); font-weight: 600; }
.dist-table td:first-child { color: var(--clr-text-3); font-size: .7rem; }
.dist-table td.active-node { background: #ECEFF1; font-weight: 700; color: var(--clr-primary); }
.dist-table td.path-node { background: rgba(0,121,107,.1); color: var(--clr-accent); font-weight: 700; }

.dijk-legend {
  display: flex;
  flex-wrap: wrap;
  gap: 8px 16px;
}
.legend-item {
  display: flex;
  align-items: center;
  gap: 6px;
  font-size: .72rem;
  color: var(--clr-text-2);
}
.legend-dot {
  width: 10px;
  height: 10px;
  border-radius: 50%;
  flex-shrink: 0;
}

/* ── Top-K layout ── */
.topk-layout {
  display: flex;
  align-items: center;
  gap: 16px;
  margin-bottom: 16px;
  flex-wrap: wrap;
}
.topk-section { flex: 1; min-width: 140px; }
.topk-label {
  font-size: .75rem;
  font-weight: 600;
  color: var(--clr-text-3);
  text-transform: uppercase;
  letter-spacing: .06em;
  margin-bottom: 10px;
}
.topk-arrow {
  font-size: 1.2rem;
  color: var(--clr-text-3);
  flex-shrink: 0;
}

.topk-stream {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  min-height: 36px;
}
.topk-num {
  width: 36px;
  height: 36px;
  border-radius: 6px;
  background: var(--clr-bg);
  border: 1px solid var(--clr-border);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: .82rem;
  font-weight: 600;
  font-family: var(--font-mono);
  color: var(--clr-text);
  transition: all .3s var(--ease);
}
.topk-num.current {
  background: var(--clr-primary);
  border-color: var(--clr-primary);
  color: #fff;
  transform: scale(1.1);
}
.topk-num.processed { opacity: .35; }
.topk-num.accepted {
  background: rgba(0,121,107,.1);
  border-color: var(--clr-accent);
  color: var(--clr-accent);
}

.topk-heap-svg {
  width: 100%;
  border: 1px solid var(--clr-border);
  border-radius: 8px;
  background: var(--clr-bg);
}

.topk-result { display: flex; flex-direction: column; gap: 6px; min-height: 120px; }
.topk-result-item {
  display: flex;
  align-items: center;
  gap: 10px;
  background: var(--clr-bg);
  border: 1px solid var(--clr-border);
  border-radius: 6px;
  padding: 8px 14px;
  font-size: .85rem;
  font-weight: 600;
  font-family: var(--font-mono);
  color: var(--clr-text);
  transition: all .3s var(--ease);
}
.topk-result-item .rank { color: var(--clr-text-3); font-size: .72rem; width: 20px; }
.topk-result-item.rank-1 {
  background: rgba(0,121,107,.06);
  border-color: rgba(0,121,107,.2);
  color: var(--clr-accent);
}

.algo-status-bar {
  background: var(--clr-bg);
  border-radius: 6px;
  padding: 10px 16px;
  font-size: .82rem;
  color: var(--clr-text-2);
  border: 1px solid var(--clr-border);
  min-height: 40px;
}

/* ── API Table ── */
.api-table-wrap {
  overflow-x: auto;
  border-radius: 12px;
  border: 1px solid var(--clr-border);
  box-shadow: var(--shadow-1);
}
.api-table {
  width: 100%;
  border-collapse: collapse;
  background: var(--clr-surface);
  font-size: .875rem;
}
.api-table thead tr {
  background: var(--clr-bg);
}
.api-table th {
  padding: 12px 16px;
  text-align: left;
  font-size: .75rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: .06em;
  color: var(--clr-text-2);
  border-bottom: 1px solid var(--clr-border);
}
.api-table td {
  padding: 13px 16px;
  border-bottom: 1px solid var(--clr-border);
  color: var(--clr-text);
  vertical-align: middle;
}
.api-table tr:last-child td { border-bottom: none; }
.api-table tr:hover td { background: var(--clr-bg); }
.api-table code {
  font-family: var(--font-mono);
  font-size: .78rem;
  color: var(--clr-primary);
  background: rgba(69,90,100,.06);
  padding: 2px 6px;
  border-radius: 4px;
}

.method-badge {
  display: inline-block;
  font-size: .7rem;
  font-weight: 700;
  font-family: var(--font-mono);
  padding: 2px 8px;
  border-radius: 4px;
  text-transform: uppercase;
  letter-spacing: .04em;
}
.method-badge.get {
  background: rgba(2,136,209,.1);
  color: #0277BD;
}
.method-badge.post {
  background: rgba(0,121,107,.1);
  color: #00796B;
}

/* ── Tech & Performance ── */
.two-col {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 48px;
  align-items: start;
}

.tech-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
}
.tech-card {
  background: var(--clr-bg);
  border: 1px solid var(--clr-border);
  border-radius: 10px;
  padding: 20px;
}
.tech-card h4 {
  font-size: .82rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: .06em;
  color: var(--clr-primary);
  margin-bottom: 12px;
}
.tech-card ul { display: flex; flex-direction: column; gap: 6px; }
.tech-card li {
  font-size: .82rem;
  color: var(--clr-text-2);
}
.tech-card strong { color: var(--clr-text); font-weight: 600; }

.perf-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
}
.perf-card {
  background: var(--clr-bg);
  border: 1px solid var(--clr-border);
  border-radius: 10px;
  padding: 24px 20px;
  text-align: center;
}
.perf-card__val {
  font-size: 1.6rem;
  font-weight: 700;
  font-family: var(--font-mono);
  color: var(--clr-primary);
  line-height: 1;
  margin-bottom: 8px;
}
.perf-card__desc {
  font-size: .78rem;
  color: var(--clr-text-2);
}

/* ── Team ── */
.team-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
  max-width: 720px;
  margin: 0 auto;
}
.team-card {
  background: var(--clr-surface);
  border: 1px solid var(--clr-border);
  border-radius: 12px;
  padding: 32px 24px;
  text-align: center;
  transition: box-shadow var(--dur) var(--ease), transform var(--dur) var(--ease);
}
.team-card:hover {
  box-shadow: var(--shadow-2);
  transform: translateY(-2px);
}
.team-card__avatar {
  width: 64px;
  height: 64px;
  border-radius: 50%;
  background: var(--clr-bg);
  border: 2px solid var(--clr-border);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.4rem;
  font-weight: 700;
  color: var(--clr-primary);
  margin: 0 auto 16px;
}
.team-card h3 {
  font-size: 1rem;
  font-weight: 700;
  color: var(--clr-text);
  margin-bottom: 6px;
}
.team-card p {
  font-size: .82rem;
  color: var(--clr-text-2);
  margin-bottom: 14px;
}
.team-card__chips {
  display: flex;
  justify-content: center;
  flex-wrap: wrap;
  gap: 6px;
}
.team-card__chips span {
  font-size: .7rem;
  color: var(--clr-text-3);
  background: var(--clr-bg);
  border: 1px solid var(--clr-border);
  padding: 2px 8px;
  border-radius: 20px;
}

/* ── Footer ── */
.footer {
  background: var(--clr-hero-bg);
  padding: 36px 0;
}
.footer__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  flex-wrap: wrap;
}
.footer__brand {
  display: flex;
  flex-direction: column;
  gap: 4px;
}
.footer__brand strong {
  font-size: .9rem;
  color: var(--clr-hero-text);
}
.footer__brand span {
  font-size: .78rem;
  color: var(--clr-hero-muted);
}
.footer__stack {
  display: flex;
  gap: 8px;
  font-size: .78rem;
  color: var(--clr-hero-muted);
}

.footer__qr {
  display: flex;
  align-items: center;
  gap: 10px;
  flex-shrink: 0;
}
.footer__qr-img { border-radius: 4px; }
.footer__qr-info {
  display: flex;
  flex-direction: column;
  gap: 3px;
}
.footer__qr-url {
  font-size: .75rem;
  font-weight: 600;
  font-family: var(--font-mono);
  color: var(--clr-hero-text);
}
.footer__qr-hint {
  font-size: .68rem;
  color: var(--clr-hero-muted);
}

/* ── Hamburger button (desktop: hidden) ── */
.nav__hamburger {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 4px;
  padding: 8px;
  border-radius: 6px;
  color: var(--clr-hero-muted);
  flex-shrink: 0;
  transition: background var(--dur) var(--ease);
}
.nav__hamburger:hover { background: rgba(255,255,255,.08); }
.nav__hamburger span {
  display: block;
  width: 18px;
  height: 2px;
  background: currentColor;
  border-radius: 2px;
  transition: transform .22s var(--ease), opacity .22s var(--ease);
}
.nav__hamburger[aria-expanded="true"] span:nth-child(1) {
  transform: translateY(6px) rotate(45deg);
}
.nav__hamburger[aria-expanded="true"] span:nth-child(2) { opacity: 0; }
.nav__hamburger[aria-expanded="true"] span:nth-child(3) {
  transform: translateY(-6px) rotate(-45deg);
}

/* ── Dist table scroll wrapper ── */
.dist-table-scroll { overflow-x: auto; -webkit-overflow-scrolling: touch; }

/* ── Innovation Section ── */
.innov-compare {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  gap: 24px;
  align-items: center;
}

.innov-vs {
  font-size: .82rem;
  font-weight: 700;
  color: var(--clr-text-3);
  letter-spacing: .06em;
  padding: 0 4px;
  text-align: center;
}

.innov-side {
  border: 1px solid var(--clr-border);
  border-radius: 12px;
  padding: 24px;
}

.innov-side--before { background: var(--clr-bg); }

.innov-side--after {
  background: rgba(0,121,107,.03);
  border-color: rgba(0,121,107,.2);
}

.innov-side__header { margin-bottom: 18px; }

.innov-badge {
  display: inline-block;
  font-size: .7rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: .07em;
  padding: 4px 12px;
  border-radius: 20px;
}
.innov-badge--muted { background: var(--clr-divider); color: var(--clr-text-2); }
.innov-badge--accent { background: rgba(0,121,107,.12); color: var(--clr-accent); }

.innov-flow {
  display: flex;
  align-items: stretch;
  margin-bottom: 18px;
}

.innov-node {
  flex: 1;
  min-width: 0;
  background: var(--clr-surface);
  border: 1px solid var(--clr-border);
  border-radius: 8px;
  padding: 12px 10px;
}

.innov-node--accent {
  border-color: rgba(0,121,107,.2);
  background: rgba(0,121,107,.04);
}

.innov-node__phase {
  font-size: .63rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: .08em;
  color: var(--clr-text-3);
  margin-bottom: 6px;
}
.innov-node--accent .innov-node__phase { color: var(--clr-accent); }

.innov-node__name {
  font-size: .82rem;
  font-weight: 600;
  color: var(--clr-text);
  margin-bottom: 3px;
  line-height: 1.3;
}

.innov-node__sub {
  font-size: .72rem;
  color: var(--clr-text-2);
}

.innov-edge {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 4px;
  padding: 0 6px;
  flex-shrink: 0;
}

.innov-edge__line {
  width: 20px;
  height: 2px;
  border-radius: 1px;
}
.innov-edge--broken .innov-edge__line {
  background: repeating-linear-gradient(
    to right,
    var(--clr-divider) 0, var(--clr-divider) 4px,
    transparent 4px, transparent 8px
  );
}
.innov-edge--solid .innov-edge__line { background: var(--clr-accent); }

.innov-edge__label {
  font-size: .58rem;
  font-weight: 600;
  white-space: nowrap;
}
.innov-edge--broken .innov-edge__label { color: var(--clr-text-3); }
.innov-edge--solid .innov-edge__label { color: var(--clr-accent); }

.innov-desc {
  font-size: .82rem;
  color: var(--clr-text-2);
  line-height: 1.65;
}

/* ── Innovation: Agent Cards ── */
.innov-agents {
  margin-top: 56px;
  padding-top: 48px;
  border-top: 1px solid var(--clr-border);
}

.innov-agents__head {
  text-align: center;
  margin-bottom: 40px;
}

.innov-agents__title {
  font-size: clamp(1.1rem, 2.5vw, 1.5rem);
  font-weight: 700;
  color: var(--clr-text);
  letter-spacing: -.02em;
  margin-bottom: 12px;
}

.innov-agents__sub {
  font-size: .9rem;
  color: var(--clr-text-2);
  line-height: 1.75;
  max-width: 600px;
  margin: 0 auto;
}

.innov-agents__grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
}

.innov-agent-card {
  background: var(--clr-bg);
  border: 1px solid var(--clr-border);
  border-radius: 12px;
  padding: 28px 24px;
  display: flex;
  flex-direction: column;
  gap: 10px;
  transition: box-shadow var(--dur) var(--ease), transform var(--dur) var(--ease);
}
.innov-agent-card:hover {
  box-shadow: var(--shadow-2);
  transform: translateY(-2px);
}

.innov-agent-card--mid {
  background: rgba(0,121,107,.03);
  border-color: rgba(0,121,107,.18);
}

.innov-agent-card__phase {
  font-size: .68rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: .1em;
  color: var(--clr-text-3);
}
.innov-agent-card--mid .innov-agent-card__phase { color: var(--clr-accent); }

.innov-agent-card__name {
  font-size: 1rem;
  font-weight: 700;
  color: var(--clr-text);
  margin-bottom: 2px;
}

.innov-agent-card__desc {
  font-size: .84rem;
  color: var(--clr-text-2);
  line-height: 1.75;
  flex: 1;
}

.innov-agent-card__calls {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin-top: 4px;
}
.innov-agent-card__calls span {
  font-size: .7rem;
  font-weight: 500;
  font-family: var(--font-mono);
  color: var(--clr-primary);
  background: rgba(69,90,100,.07);
  border: 1px solid rgba(69,90,100,.12);
  padding: 3px 9px;
  border-radius: 4px;
}
.innov-agent-card--mid .innov-agent-card__calls span {
  color: var(--clr-accent);
  background: rgba(0,121,107,.07);
  border-color: rgba(0,121,107,.15);
}

/* ── Responsive: Tablet (≤ 900px) ── */
@media (max-width: 900px) {
  .hero__inner {
    flex-direction: column;
    text-align: center;
    padding-top: 100px;
  }
  .hero__team { justify-content: center; }
  .hero__stack { justify-content: center; }
  .hero__qr { justify-content: center; }
  .hero__visual { max-width: 320px; }

  .innov-compare { grid-template-columns: 1fr; }
  .innov-vs { padding: 8px 0; }
  .innov-agents__grid { grid-template-columns: 1fr; }
  .features-grid { grid-template-columns: 1fr 1fr; }
  .arch-wrap { grid-template-columns: 1fr; }
  .arch-stats { flex-direction: row; flex-wrap: wrap; }
  .arch-stat { flex: 1; min-width: 120px; }
  .ds-split { grid-template-columns: 1fr; }
  .dijkstra-layout { grid-template-columns: 1fr; }
  .two-col { grid-template-columns: 1fr; }
  .team-grid { grid-template-columns: 1fr 1fr; max-width: 480px; }
  .algo-card__hd { flex-direction: column; align-items: flex-start; gap: 16px; }
  .algo-controls { flex-wrap: wrap; }
}

/* ── Responsive: Mobile (≤ 600px) ── */
@media (max-width: 600px) {
  :root { --section-pad: 48px; }

  /* Nav */
  .nav__hamburger { display: flex; }
  .nav__links {
    position: fixed;
    top: 56px; left: 0; right: 0;
    background: #1c313a;
    flex-direction: column;
    gap: 0;
    padding: 4px 0 8px;
    border-top: 1px solid rgba(255,255,255,.08);
    box-shadow: 0 8px 24px rgba(0,0,0,.3);
    transform: translateY(-8px);
    opacity: 0;
    pointer-events: none;
    transition: transform .22s var(--ease), opacity .22s var(--ease);
    z-index: 99;
  }
  .nav__links.open {
    transform: translateY(0);
    opacity: 1;
    pointer-events: auto;
  }
  .nav__links li { width: 100%; }
  .nav__link {
    display: block;
    padding: 14px 24px;
    font-size: .9rem;
    border-bottom: 1px solid rgba(255,255,255,.05);
  }
  .nav__links li:last-child .nav__link { border-bottom: none; }

  /* Hero */
  .hero { min-height: 100svh; min-height: 100vh; }
  .hero__inner {
    padding: 80px 20px 48px;
    gap: 32px;
  }
  .hero__visual { display: none; }   /* 小屏隐藏装饰图，专注内容 */
  .hero__title { font-size: 2rem; }
  .hero__desc { font-size: .9rem; }
  .hero__team { flex-wrap: wrap; gap: 12px; }
  .hero__sep { display: none; }
  .hero__qr { justify-content: center; }

  /* Sections */
  .section-head { margin-bottom: 36px; }
  .features-grid { grid-template-columns: 1fr; }

  /* Architecture */
  .arch-stats {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 12px;
  }
  .arch-layer__items { gap: 6px; }
  .arch-chip { font-size: .75rem; }

  /* Data structures */
  .tab-bar { overflow-x: auto; -webkit-overflow-scrolling: touch; }
  .tab-btn { padding: 12px 14px; font-size: .8rem; white-space: nowrap; min-height: 44px; }
  .tab-pane { padding: 20px 16px; }
  .ds-meta { font-size: .78rem; }
  .code-block { font-size: .72rem; }

  /* Algorithm cards */
  .algo-card__hd { padding: 18px 16px; }
  .algo-card__bd { padding: 16px; }
  .algo-controls { width: 100%; }
  .algo-controls .btn { flex: 1; min-height: 44px; font-size: .8rem; }
  .algo-complexity { flex-wrap: wrap; gap: 6px; }

  /* Dijkstra */
  .dijk-status-box { font-size: .8rem; }
  .dijk-svg { min-height: 220px; }

  /* Top-K */
  .topk-layout { flex-direction: column; align-items: stretch; gap: 12px; }
  .topk-arrow { transform: rotate(90deg); text-align: center; }
  .topk-section { min-width: unset; }

  /* Tech grid */
  .tech-grid { grid-template-columns: 1fr; }
  .perf-grid { grid-template-columns: 1fr 1fr; }

  /* Team */
  .team-grid { grid-template-columns: 1fr; max-width: 280px; }

  /* Buttons */
  .btn { min-height: 40px; }

  /* Footer */
  .footer__inner {
    flex-direction: column;
    align-items: center;
    text-align: center;
    gap: 20px;
  }
  .footer__stack { flex-wrap: wrap; justify-content: center; }
  .footer__qr { flex-direction: column; align-items: center; text-align: center; }
}

/* ── Responsive: Small mobile (≤ 400px) ── */
@media (max-width: 400px) {
  .hero__title { font-size: 1.75rem; }
  .perf-grid { grid-template-columns: 1fr; }
  .arch-stats { grid-template-columns: 1fr 1fr; }
  .hero__member span { font-size: .8rem; }
}