/* =============================================
   BASE & RESET
   ============================================= */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

:root {
  --color-bg:        #0d0f14;
  --color-surface:   #151820;
  --color-surface2:  #1c2030;
  --color-border:    #2a2f45;
  --color-primary:   #6c8fff;
  --color-primary2:  #a78bfa;
  --color-accent:    #38bdf8;
  --color-text:      #e2e8f0;
  --color-muted:     #8892a4;
  --color-lyric:     #a78bfa;
  --color-white:     #ffffff;

  --font-sans:  'Inter', system-ui, sans-serif;
  --font-serif: 'Playfair Display', Georgia, serif;

  --radius-card: 14px;
  --radius-sm:    8px;

  --shadow-card: 0 4px 24px rgba(0,0,0,0.45);
  --shadow-glow: 0 0 40px rgba(108,143,255,0.15);

  --transition: 0.3s cubic-bezier(0.4,0,0.2,1);
}

html {
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-sans);
  background-color: var(--color-bg);
  color: var(--color-text);
  line-height: 1.7;
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
}

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

.container {
  max-width: 1140px;
  margin: 0 auto;
  padding: 0 24px;
}

/* =============================================
   HERO
   ============================================= */
.hero {
  position: relative;
  padding: 100px 24px 80px;
  text-align: center;
  overflow: hidden;
  background: radial-gradient(ellipse 80% 60% at 50% 0%,
    rgba(108,143,255,0.18) 0%,
    transparent 70%),
    var(--color-bg);
}

/* animated grid lines background */
.hero::before {
  content: '';
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(rgba(108,143,255,0.06) 1px, transparent 1px),
    linear-gradient(90deg, rgba(108,143,255,0.06) 1px, transparent 1px);
  background-size: 48px 48px;
  pointer-events: none;
}



.venue-badge {
  display: inline-block;
  background: linear-gradient(135deg, var(--color-primary), var(--color-primary2));
  color: #fff;
  font-size: 0.78rem;
  font-weight: 600;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  padding: 5px 18px;
  border-radius: 999px;
  margin-bottom: 28px;
}

.hero-inner {
  position: relative;
  z-index: 1;
  width: min(92%, 1100px);
  margin: 0 auto;
}

.paper-title {
  font-family: var(--font-serif);
  font-size: clamp(1.8rem, 4vw, 2.8rem);
  font-weight: 700;
  line-height: 1.18;
  color: var(--color-white);
  margin: 0 auto 1.75rem;
  letter-spacing: -0.02em;
  width: 100%;
}


.authors {
  font-size: 1.02rem;
  font-weight: 500;
  color: var(--color-text);
  margin-bottom: 6px;
  line-height: 1.8;
}

.affiliation {
  font-size: 0.92rem;
  color: var(--color-muted);
  margin-bottom: 36px;
}

/* Buttons */
.btn-group {
  display: flex;
  gap: 12px;
  justify-content: center;
  flex-wrap: wrap;
  margin-bottom: 56px;
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 7px;
  padding: 10px 24px;
  border-radius: 999px;
  font-size: 0.92rem;
  font-weight: 600;
  transition: all var(--transition);
  cursor: pointer;
  border: 2px solid transparent;
}

.btn-primary {
  background: linear-gradient(135deg, var(--color-primary), var(--color-primary2));
  color: #fff;
  box-shadow: 0 4px 20px rgba(108,143,255,0.35);
}
.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 28px rgba(108,143,255,0.5);
  color: #fff;
}

.btn-outline {
  border-color: var(--color-border);
  color: var(--color-text);
  background: rgba(255,255,255,0.04);
  backdrop-filter: blur(8px);
}
.btn-outline:hover {
  border-color: var(--color-primary);
  color: var(--color-primary);
  transform: translateY(-2px);
}

/* Teaser */
.teaser-wrap {
  margin-top: 8px;
}

.teaser-video {
  width: 100%;
  max-width: 780px;
  border-radius: 16px;
  border: 1px solid var(--color-border);
  box-shadow: var(--shadow-card), var(--shadow-glow);
  display: block;
  margin: 0 auto;
}

.teaser-caption {
  margin-top: 14px;
  font-size: 0.88rem;
  color: var(--color-muted);
  font-style: italic;
}

/* =============================================
   SECTIONS
   ============================================= */
.section {
  padding: 88px 0;
}

.section-light {
  background-color: var(--color-bg);
}

.section-dark {
  background-color: var(--color-surface);
  border-top: 1px solid var(--color-border);
  border-bottom: 1px solid var(--color-border);
}

.sec-title {
  font-family: var(--font-serif);
  font-size: clamp(1.6rem, 3vw, 2.2rem);
  font-weight: 700;
  color: var(--color-white);
  text-align: center;
  margin-bottom: 16px;
  position: relative;
}

/* underline accent */
.sec-title::after {
  content: '';
  display: block;
  width: 56px;
  height: 3px;
  background: linear-gradient(90deg, var(--color-primary), var(--color-primary2));
  border-radius: 999px;
  margin: 12px auto 0;
}

.sec-title-light {
  color: var(--color-white);
}

.sec-sub {
  text-align: center;
  color: var(--color-muted);
  max-width: 700px;
  margin: 0 auto 56px;
  font-size: 0.97rem;
  line-height: 1.8;
}

.sec-sub-light {
  color: #7a8499;
}

/* =============================================
   ABSTRACT
   ============================================= */
.abstract-box {
  max-width: 780px;
  margin: 32px auto 0;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-card);
  padding: 40px 48px;
  box-shadow: var(--shadow-card);
}

.abstract-box p {
  color: var(--color-text);
  font-size: 0.97rem;
  line-height: 1.9;
  margin-bottom: 18px;
}
.abstract-box p:last-child { margin-bottom: 0; }

/* =============================================
   METHOD CARDS
   ============================================= */
.method-cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 20px;
  margin-top: 44px;
}

.method-card {
  background: var(--color-surface2);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-card);
  padding: 32px 28px;
  transition: transform var(--transition), box-shadow var(--transition),
              border-color var(--transition);
}

.method-card:hover {
  transform: translateY(-5px);
  box-shadow: 0 12px 36px rgba(0,0,0,0.5);
  border-color: var(--color-primary);
}

.method-icon {
  font-size: 2rem;
  margin-bottom: 16px;
}

.method-card h3 {
  font-size: 1rem;
  font-weight: 600;
  color: var(--color-white);
  margin-bottom: 10px;
}

.method-card p {
  font-size: 0.88rem;
  color: var(--color-muted);
  line-height: 1.75;
}

/* =============================================
   DOMAIN BLOCKS
   ============================================= */
.domain-block {
  margin-top: 72px;
}

.domain-block:first-of-type {
  margin-top: 48px;
}

.domain-title {
  font-size: 1.3rem;
  font-weight: 600;
  color: var(--color-white);
  margin-bottom: 10px;
  display: flex;
  align-items: center;
  gap: 10px;
}

.domain-emoji {
  font-size: 1.4rem;
}

.domain-desc {
  color: var(--color-muted);
  font-size: 0.93rem;
  max-width: 680px;
  margin-bottom: 28px;
  line-height: 1.8;
}

/* =============================================
   VIDEO GRID
   ============================================= */
.video-grid {
  display: grid;
  gap: 20px;
}

.grid-3 {
  grid-template-columns: repeat(3, 1fr);
}

.grid-2-center {
  grid-template-columns: repeat(2, 1fr);
  max-width: 720px;
}

/* VIDEO CARD */
.vcard {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-card);
  overflow: hidden;
  transition: transform var(--transition), box-shadow var(--transition),
              border-color var(--transition);
  display: flex;
  flex-direction: column;
}

.vcard:hover {
  transform: translateY(-4px);
  box-shadow: 0 16px 40px rgba(0,0,0,0.55);
  border-color: rgba(108,143,255,0.4);
}

.vcard-video {
  width: 100%;
  background: #000;
  aspect-ratio: 16/9;
  overflow: hidden;
}

.vcard-video video {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
}

.vcard-caption {
  padding: 14px 16px 16px;
  font-size: 0.82rem;
  color: var(--color-muted);
  line-height: 1.7;
  flex: 1;
}

.lyric {
  display: block;
  margin-top: 6px;
  color: var(--color-lyric);
  font-style: italic;
  font-size: 0.8rem;
}

/* =============================================
   CITATION
   ============================================= */
.bibtex-box {
  position: relative;
  background: #0a0c12;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-card);
  padding: 32px 36px;
  max-width: 700px;
  margin: 32px auto 0;
}

.bibtex-box pre {
  font-family: 'JetBrains Mono', 'Fira Code', monospace;
  font-size: 0.85rem;
  color: #7dd3fc;
  line-height: 1.8;
  white-space: pre-wrap;
  word-break: break-word;
}

.copy-btn {
  position: absolute;
  top: 14px;
  right: 16px;
  background: rgba(108,143,255,0.15);
  border: 1px solid var(--color-border);
  color: var(--color-primary);
  font-size: 0.8rem;
  font-weight: 600;
  padding: 5px 14px;
  border-radius: 999px;
  cursor: pointer;
  transition: all var(--transition);
}

.copy-btn:hover {
  background: rgba(108,143,255,0.3);
  border-color: var(--color-primary);
}

.copy-btn.copied {
  background: rgba(56,189,248,0.2);
  border-color: var(--color-accent);
  color: var(--color-accent);
}

/* =============================================
   FOOTER
   ============================================= */
.footer {
  padding: 48px 24px;
  text-align: center;
  background: var(--color-bg);
  border-top: 1px solid var(--color-border);
}

.footer p {
  font-size: 0.88rem;
  color: var(--color-muted);
  margin-bottom: 8px;
}

.footer p strong {
  color: var(--color-text);
}

.footer-notice {
  font-size: 0.82rem !important;
  color: #5a6478 !important;
  margin-top: 6px;
}

.footer-credit {
  margin-top: 16px !important;
  font-size: 0.8rem !important;
}

.footer-credit a {
  color: var(--color-primary);
}
.footer-credit a:hover {
  color: var(--color-accent);
}

/* =============================================
   SCROLL FADE-IN ANIMATION
   ============================================= */
.fade-in {
  opacity: 0;
  transform: translateY(28px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

.fade-in.visible {
  opacity: 1;
  transform: translateY(0);
}

/* stagger delay for grid children */
.video-grid .fade-in:nth-child(1) { transition-delay: 0.05s; }
.video-grid .fade-in:nth-child(2) { transition-delay: 0.15s; }
.video-grid .fade-in:nth-child(3) { transition-delay: 0.25s; }

.method-cards .method-card:nth-child(1) { transition-delay: 0.05s; }
.method-cards .method-card:nth-child(2) { transition-delay: 0.13s; }
.method-cards .method-card:nth-child(3) { transition-delay: 0.21s; }
.method-cards .method-card:nth-child(4) { transition-delay: 0.29s; }

/* =============================================
   STICKY NAV (top bar that appears on scroll)
   ============================================= */
.topnav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 999;
  background: rgba(13,15,20,0.85);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--color-border);
  padding: 0 32px;
  height: 52px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  transform: translateY(-100%);
  transition: transform 0.35s cubic-bezier(0.4,0,0.2,1);
}

.topnav.show {
  transform: translateY(0);
}

.topnav-title {
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--color-white);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  max-width: 360px;
}

.topnav-links {
  display: flex;
  gap: 24px;
  list-style: none;
}

.topnav-links a {
  font-size: 0.82rem;
  font-weight: 500;
  color: var(--color-muted);
  transition: color var(--transition);
}

.topnav-links a:hover {
  color: var(--color-primary);
}

/* =============================================
   SCROLLBAR
   ============================================= */
::-webkit-scrollbar {
  width: 6px;
}
::-webkit-scrollbar-track {
  background: var(--color-bg);
}
::-webkit-scrollbar-thumb {
  background: var(--color-border);
  border-radius: 999px;
}
::-webkit-scrollbar-thumb:hover {
  background: var(--color-primary);
}

/* =============================================
   SELECTION
   ============================================= */
::selection {
  background: rgba(108,143,255,0.3);
  color: var(--color-white);
}

/* =============================================
   RESPONSIVE
   ============================================= */
@media (max-width: 900px) {
  .grid-3 {
    grid-template-columns: repeat(2, 1fr);
  }

  .abstract-box {
    padding: 28px 28px;
  }

  .topnav-links {
    display: none;
  }
}

@media (max-width: 600px) {
  .hero {
    padding: 72px 20px 60px;
  }

  .paper-title {
    font-size: 1.65rem;
  }

  .grid-3,
  .grid-2-center {
    grid-template-columns: 1fr;
  }

  .grid-2-center {
    max-width: 100%;
  }

  .abstract-box {
    padding: 24px 20px;
  }

  .bibtex-box {
    padding: 44px 20px 24px;
  }

  .method-cards {
    grid-template-columns: 1fr;
  }

  .section {
    padding: 60px 0;
  }

  .topnav {
    padding: 0 20px;
  }

  .topnav-title {
    max-width: 240px;
    font-size: 0.78rem;
  }
}


/* =============================================
   AUTHOR LINKS / AFFILIATION ENHANCEMENT
   ============================================= */
.authors a {
  color: var(--color-text);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: all var(--transition);
}

.authors a:hover {
  color: var(--color-primary);
  border-color: rgba(108,143,255,0.4);
}

.affiliation {
  font-size: 0.92rem;
  color: var(--color-muted);
  margin-bottom: 36px;
  line-height: 1.8;
}

.affiliation .inst {
  display: inline-block;
  margin: 0 10px;
}

/* =============================================
   HERO TEASER IMAGE
   ============================================= */
.teaser-image {
  width: 100%;
  max-width: 900px;
  border-radius: 16px;
  border: 1px solid var(--color-border);
  box-shadow: var(--shadow-card), var(--shadow-glow);
  display: block;
  margin: 0 auto 18px;
  background: #000;
}

/* =============================================
   FIGURE CARD
   ============================================= */
.figure-card {
  max-width: 980px;
  margin: 36px auto 0;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-card);
  padding: 18px;
  box-shadow: var(--shadow-card);
}

.figure-card img {
  width: 100%;
  display: block;
  border-radius: 10px;
}

.figure-caption {
  margin-top: 12px;
  font-size: 0.9rem;
  color: var(--color-muted);
  line-height: 1.8;
  text-align: left;
}

/* =============================================
   BUTTON GROUP POLISH
   ============================================= */
.btn-group.compact {
  margin-bottom: 42px;
}

.btn .emoji {
  font-size: 0.95rem;
  line-height: 1;
}

/* =============================================
   SECTION ANCHOR OFFSET
   ============================================= */
section[id] {
  scroll-margin-top: 72px;
}