/* ============================================================
   FGGS-LiDAR project page
   Dark, token-driven theme (inspired by gsplayground / unilabsim)
   ============================================================ */

:root {
  color-scheme: dark;

  /* surfaces */
  --bg:        #06091a;
  --bg-alt:    #0a0f24;
  --card:      #0d1330;
  --card-2:    #111838;
  --footer:    #04061a;
  --border:    rgba(255, 255, 255, 0.08);
  --border-strong: rgba(255, 255, 255, 0.16);

  /* text */
  --text:      #e6e8f3;
  --muted:     #a8aed0;
  --faint:     #7b82a8;

  /* accents */
  --cyan:      #22d3ee;
  --blue:      #38bdf8;
  --indigo:    #818cf8;
  --mint:      #34d399;
  --amber:     #fbbf24;
  --accent-grad: linear-gradient(135deg, #5eead4 0%, #38bdf8 50%, #818cf8 100%);
  --glow-cyan: 0 0 28px rgba(34, 211, 238, 0.18);

  /* layout */
  --container: 1120px;
  --radius:    16px;
  --radius-sm: 10px;

  --font-sans: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", "Noto Sans",
               "Helvetica Neue", Arial, "PingFang SC", "Microsoft YaHei", sans-serif;
  --font-mono: "JetBrains Mono", "SFMono-Regular", Menlo, Consolas, monospace;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; scroll-padding-top: 86px; }

body {
  margin: 0;
  font-family: var(--font-sans);
  background: var(--bg);
  color: var(--text);
  line-height: 1.65;
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
  overflow-x: hidden;
}

/* faint teaser backdrop behind everything */
body::before {
  content: "";
  position: fixed;
  inset: 0;
  background:
    radial-gradient(1200px 600px at 70% -10%, rgba(56, 189, 248, 0.10), transparent 60%),
    radial-gradient(1000px 600px at 10% 10%, rgba(129, 140, 248, 0.08), transparent 55%);
  pointer-events: none;
  z-index: -1;
}

a { color: var(--blue); text-decoration: none; transition: color 0.2s ease; }
a:hover { color: var(--cyan); }

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

/* ---------- i18n: show one language at a time ---------- */
html[data-lang="en"] .i18n-zh { display: none !important; }
html[data-lang="zh"] .i18n-en { display: none !important; }
html[data-lang="zh"] body { font-family: var(--font-sans); }

/* ============================================================
   Navbar
   ============================================================ */
.nav {
  position: sticky;
  top: 0;
  z-index: 50;
  background: rgba(6, 9, 26, 0.72);
  backdrop-filter: saturate(180%) blur(14px);
  -webkit-backdrop-filter: saturate(180%) blur(14px);
  border-bottom: 1px solid var(--border);
}
.nav-inner {
  display: flex;
  align-items: center;
  gap: 18px;
  height: 64px;
  max-width: var(--container);
  margin: 0 auto;
  padding: 0 24px;
}
.brand {
  display: flex;
  align-items: center;
  gap: 10px;
  font-weight: 800;
  letter-spacing: 0.2px;
  color: var(--text);
  font-size: 1.05rem;
}
.brand .logo {
  width: 26px; height: 26px;
  border-radius: 7px;
  background: var(--accent-grad);
  box-shadow: var(--glow-cyan);
  flex: none;
}
.nav-links {
  display: flex;
  align-items: center;
  gap: 22px;
  margin-left: 14px;
}
.nav-links a {
  color: var(--muted);
  font-size: 0.92rem;
  font-weight: 500;
}
.nav-links a:hover { color: var(--text); }
.nav-right {
  margin-left: auto;
  display: flex;
  align-items: center;
  gap: 10px;
}
.nav-ghost {
  display: inline-flex; align-items: center; gap: 6px;
  height: 36px; padding: 0 14px;
  border: 1px solid var(--border-strong);
  border-radius: 999px;
  color: var(--text);
  font-size: 0.85rem; font-weight: 600;
}
.nav-ghost:hover { border-color: var(--cyan); color: var(--cyan); }

/* language toggle */
.lang-toggle {
  display: inline-flex;
  border: 1px solid var(--border-strong);
  border-radius: 999px;
  overflow: hidden;
  font-size: 0.8rem;
  font-weight: 700;
}
.lang-toggle button {
  background: transparent;
  border: none;
  color: var(--muted);
  padding: 6px 12px;
  cursor: pointer;
  font-family: inherit;
  transition: all 0.2s ease;
}
.lang-toggle button.active {
  background: var(--accent-grad);
  color: #06091a;
}

.nav-burger { display: none; }

/* ============================================================
   Buttons
   ============================================================ */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  height: 44px;
  padding: 0 20px;
  border-radius: 999px;
  font-weight: 700;
  font-size: 0.95rem;
  border: 1px solid var(--border-strong);
  color: var(--text);
  background: rgba(255, 255, 255, 0.03);
  transition: transform 0.15s ease, border-color 0.2s ease, color 0.2s ease, box-shadow 0.2s ease;
}
.btn svg { width: 18px; height: 18px; }
.btn:hover { transform: translateY(-2px); border-color: var(--cyan); color: var(--cyan); }
.btn-primary {
  background: var(--accent-grad);
  color: #06091a;
  border-color: transparent;
  box-shadow: var(--glow-cyan);
}
.btn-primary:hover { color: #06091a; opacity: 0.92; }

/* ============================================================
   Hero
   ============================================================ */
.hero {
  padding: 80px 0 40px;
  text-align: center;
}
.eyebrow {
  display: inline-block;
  font-size: 0.78rem;
  font-weight: 700;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--cyan);
  margin-bottom: 18px;
}
.hero h1 {
  font-size: clamp(2.6rem, 6vw, 4.2rem);
  line-height: 1.02;
  margin: 0 0 14px;
  font-weight: 800;
  letter-spacing: -0.02em;
  background: linear-gradient(180deg, #ffffff 0%, #b9c2ee 100%);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
}
.hero .subtitle {
  max-width: 760px;
  margin: 0 auto 22px;
  font-size: clamp(1.05rem, 2.2vw, 1.3rem);
  color: var(--muted);
  font-weight: 500;
}

/* acceptance banner */
.accept-banner {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  margin: 6px auto 26px;
  padding: 9px 20px;
  border-radius: 999px;
  font-weight: 800;
  font-size: 1.02rem;
  color: #06091a;
  background: linear-gradient(135deg, #fbbf24, #f59e0b);
  box-shadow: 0 0 26px rgba(251, 191, 36, 0.28);
}

/* authors */
.authors {
  max-width: 880px;
  margin: 0 auto 8px;
  font-size: 1.05rem;
  color: var(--text);
  line-height: 1.9;
}
.authors sup { color: var(--cyan); font-weight: 700; }
.affil {
  max-width: 880px;
  margin: 6px auto 30px;
  font-size: 0.92rem;
  color: var(--faint);
}
.affil sup { color: var(--cyan); }
.note-line {
  font-size: 0.86rem;
  color: var(--faint);
  margin-top: 4px;
}

.cta-row {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  justify-content: center;
  margin-top: 8px;
}

/* ============================================================
   Sections
   ============================================================ */
.section { padding: 64px 0; }
.section-alt { background: var(--bg-alt); border-top: 1px solid var(--border); border-bottom: 1px solid var(--border); }
.section-head { text-align: center; margin-bottom: 40px; }
.section-head .eyebrow { margin-bottom: 10px; }
.section h2 {
  font-size: clamp(1.8rem, 3.5vw, 2.5rem);
  margin: 0 0 6px;
  font-weight: 800;
  letter-spacing: -0.01em;
}
.lead {
  max-width: 820px;
  margin: 0 auto;
  text-align: justify;
  color: var(--muted);
  font-size: 1.05rem;
}
.lead.center { text-align: center; }

/* ============================================================
   Teaser / video
   ============================================================ */
.media-wrap {
  border-radius: var(--radius);
  overflow: hidden;
  border: 1px solid var(--border);
  background: #000;
  box-shadow: 0 24px 60px rgba(0, 0, 0, 0.45);
}
video.demo, img.figure {
  display: block;
  width: 100%;
  height: auto;
}
img.figure { background: #0b1024; }
.caption {
  text-align: center;
  color: var(--faint);
  font-size: 0.92rem;
  margin-top: 14px;
}
.video-stack > * + * { margin-top: 36px; }

/* ============================================================
   Metric grid
   ============================================================ */
.metrics {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 16px;
}
.metric {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 26px 22px;
  text-align: center;
  transition: transform 0.2s ease, border-color 0.2s ease;
}
.metric:hover { transform: translateY(-3px); border-color: var(--border-strong); }
.metric .num {
  font-family: var(--font-mono);
  font-size: 1.9rem;
  font-weight: 700;
  background: var(--accent-grad);
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
  line-height: 1.1;
}
.metric .label { color: var(--muted); font-size: 0.92rem; margin-top: 8px; }

/* ============================================================
   Highlights (contribution cards)
   ============================================================ */
.cards {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 18px;
}
.card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 28px 24px;
  transition: transform 0.2s ease, border-color 0.2s ease;
}
.card:hover { transform: translateY(-3px); border-color: var(--border-strong); }
.card .idx {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  font-weight: 700;
  color: var(--cyan);
  letter-spacing: 0.1em;
}
.card h3 { margin: 10px 0 8px; font-size: 1.18rem; font-weight: 700; }
.card p { color: var(--muted); font-size: 0.96rem; margin: 0; }

/* ============================================================
   Method blocks (figure + text)
   ============================================================ */
.block { margin-top: 48px; }
.block:first-of-type { margin-top: 0; }
.block h3 {
  font-size: 1.5rem;
  font-weight: 700;
  text-align: center;
  margin: 0 0 4px;
}
.block .sub {
  text-align: center;
  color: var(--cyan);
  font-family: var(--font-mono);
  font-size: 0.82rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  margin-bottom: 20px;
}
.block .figure { border-radius: var(--radius); border: 1px solid var(--border); }
.block .explain {
  max-width: 880px;
  margin: 18px auto 0;
  text-align: justify;
  color: var(--muted);
  font-size: 1rem;
}
.block .explain + .explain { margin-top: 12px; }
.block .explain b { color: var(--text); }

/* ============================================================
   BibTeX
   ============================================================ */
.bibtex-box {
  position: relative;
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 22px 22px 18px;
  max-width: 880px;
  margin: 0 auto;
}
.bibtex-box pre {
  margin: 0;
  overflow-x: auto;
  font-family: var(--font-mono);
  font-size: 0.85rem;
  line-height: 1.6;
  color: var(--text);
}
.copy-btn {
  position: absolute;
  top: 14px; right: 14px;
  height: 32px; padding: 0 14px;
  border-radius: 8px;
  border: 1px solid var(--border-strong);
  background: rgba(255, 255, 255, 0.04);
  color: var(--muted);
  font-family: var(--font-sans);
  font-size: 0.8rem; font-weight: 600;
  cursor: pointer;
  transition: all 0.2s ease;
}
.copy-btn:hover { color: var(--cyan); border-color: var(--cyan); }

/* ============================================================
   Footer
   ============================================================ */
.footer {
  background: var(--footer);
  border-top: 1px solid var(--border);
  padding: 40px 0 32px;
  text-align: center;
  color: var(--faint);
  font-size: 0.9rem;
}
.footer a { color: var(--muted); }
.footer .foot-links {
  display: flex; flex-wrap: wrap; gap: 18px; justify-content: center;
  margin-bottom: 16px;
}

/* ============================================================
   Data tables
   ============================================================ */
.table-card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 22px;
  margin-top: 30px;
  overflow-x: auto;
}
.table-card h3 {
  font-size: 1.2rem;
  font-weight: 700;
  margin: 0 0 4px;
  text-align: center;
}
.table-card .sub {
  text-align: center;
  color: var(--cyan);
  font-family: var(--font-mono);
  font-size: 0.78rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  margin-bottom: 16px;
}
table.data {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.9rem;
  min-width: 460px;
}
table.data th, table.data td {
  padding: 9px 12px;
  text-align: center;
  border-bottom: 1px solid var(--border);
  white-space: nowrap;
}
table.data thead th {
  color: var(--muted);
  font-weight: 700;
  border-bottom: 1px solid var(--border-strong);
}
table.data thead tr.grouphdr th { color: var(--text); }
table.data td.name, table.data th.name { text-align: left; }
table.data tr.group td {
  color: var(--cyan);
  font-weight: 700;
  text-align: left;
  background: rgba(34, 211, 238, 0.06);
  font-family: var(--font-mono);
  font-size: 0.78rem;
  letter-spacing: 0.04em;
}
table.data td.best { background: rgba(52, 211, 153, 0.16); color: #d7ffe9; font-weight: 700; }
table.data td.snd  { background: rgba(251, 191, 36, 0.14); }
table.data tr.sum td { font-weight: 700; border-top: 1px solid var(--border-strong); }
.table-note { color: var(--faint); font-size: 0.82rem; margin-top: 12px; line-height: 1.5; }
.legend { display: inline-flex; gap: 14px; flex-wrap: wrap; font-size: 0.78rem; color: var(--faint); margin-top: 10px; }
.legend span { display: inline-flex; align-items: center; gap: 6px; }
.legend i { width: 12px; height: 12px; border-radius: 3px; display: inline-block; }
.legend i.b { background: rgba(52, 211, 153, 0.5); }
.legend i.s { background: rgba(251, 191, 36, 0.5); }

/* ============================================================
   Paper blog (article)
   ============================================================ */
.article { max-width: 820px; margin: 0 auto; }
.article .anchor { scroll-margin-top: 86px; }
.article h2 {
  font-size: clamp(1.5rem, 3vw, 2rem);
  margin: 48px 0 14px;
  font-weight: 800;
  border-bottom: 1px solid var(--border);
  padding-bottom: 10px;
}
.article h2 .secnum { color: var(--cyan); font-family: var(--font-mono); margin-right: 10px; font-size: 0.9em; }
.article h3 { font-size: 1.15rem; font-weight: 700; margin: 28px 0 8px; color: var(--text); }
.article p { color: var(--muted); margin: 0 0 14px; text-align: justify; }
.article p b, .article p strong { color: var(--text); }
.article ul { color: var(--muted); padding-left: 1.2em; }
.article li { margin-bottom: 8px; }
.article figure { margin: 30px 0; }
.article figure img { width: 100%; border-radius: var(--radius); border: 1px solid var(--border); display: block; }
.article figcaption { color: var(--faint); font-size: 0.88rem; margin-top: 12px; text-align: justify; }
.eq {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 10px 16px;
  margin: 16px 0;
  overflow-x: auto;
  text-align: center;
}
.refs { font-size: 0.85rem; color: var(--faint); }
.refs li { margin-bottom: 6px; }

/* ============================================================
   Responsive
   ============================================================ */
@media (max-width: 860px) {
  .nav-links { display: none; }
  .nav-links.open {
    display: flex;
    position: absolute;
    top: 64px; left: 0; right: 0;
    flex-direction: column;
    gap: 0;
    background: rgba(6, 9, 26, 0.97);
    border-bottom: 1px solid var(--border);
    padding: 8px 24px 16px;
    margin-left: 0;
  }
  .nav-links.open a { padding: 10px 0; }
  .nav-burger {
    display: inline-flex;
    width: 40px; height: 36px;
    align-items: center; justify-content: center;
    border: 1px solid var(--border-strong);
    border-radius: 8px;
    background: transparent;
    color: var(--text);
    cursor: pointer;
  }
  .metrics { grid-template-columns: repeat(2, 1fr); }
  .cards { grid-template-columns: 1fr; }
  .nav-ghost span.hide-sm { display: none; }
}
@media (max-width: 520px) {
  .metrics { grid-template-columns: 1fr; }
  .hero { padding: 56px 0 30px; }
}