/* ============================================================
   RobustSpeechFlow Demo Page — Main Stylesheet
   ============================================================
   Table of Contents:
     1.  Variables & Reset
     2.  Background Effects
     3.  Layout
     4.  Navigation
     5.  Buttons
     6.  Hero
     7.  Key Highlights (stat cards)
     8.  Sections (common)
     9.  Abstract
    10.  Method Overview
    11.  Results & Tables
    12.  Figure Grid (CER curves)
    13.  Audio Demos & Tabs
    14.  Download / Evaluation Sets
    15.  Footer
    16.  Utilities (divider, animations)
    17.  Responsive
   ============================================================ */


/* ==========================================================
   1. Variables & Reset
   ========================================================== */

:root {
  --primary: #6366f1;
  --primary-light: #818cf8;
  --primary-dark: #4f46e5;
  --accent: #06b6d4;
  --accent-light: #22d3ee;
  --bg: #0f0f1a;
  --bg-card: #1a1a2e;
  --bg-card-alt: #16162a;
  --surface: #252542;
  --text: #e2e8f0;
  --text-muted: #94a3b8;
  --text-dim: #64748b;
  --border: #2d2d4a;
  --glow: rgba(99, 102, 241, 0.15);
  --success: #10b981;
  --warning: #f59e0b;
  --radius: 12px;
}

* { margin: 0; padding: 0; box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.7;
  overflow-x: hidden;
}


/* ==========================================================
   2. Background Effects
   ========================================================== */

.noise-overlay {
  position: fixed;
  inset: 0;
  pointer-events: none;
  z-index: 9999;
  opacity: 0.03;
  background-image: url("data:image/svg+xml,%3Csvg viewBox='0 0 256 256' xmlns='http://www.w3.org/2000/svg'%3E%3Cfilter id='noise'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.9' numOctaves='4' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23noise)'/%3E%3C/svg%3E");
}

.bg-grid {
  position: fixed;
  inset: 0;
  pointer-events: none;
  z-index: 0;
  background-size: 60px 60px;
  background-image:
    linear-gradient(to right, rgba(99,102,241,0.04) 1px, transparent 1px),
    linear-gradient(to bottom, rgba(99,102,241,0.04) 1px, transparent 1px);
  mask-image: radial-gradient(ellipse 80% 60% at 50% 30%, black 30%, transparent 100%);
}


/* ==========================================================
   3. Layout
   ========================================================== */

.container {
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 24px;
  position: relative;
  z-index: 1;
}


/* ==========================================================
   4. Navigation
   ========================================================== */

nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  backdrop-filter: blur(20px) saturate(1.5);
  background: rgba(15, 15, 26, 0.75);
  border-bottom: 1px solid var(--border);
  transition: box-shadow 0.3s;
}

nav.scrolled {
  box-shadow: 0 4px 30px rgba(0,0,0,0.3);
}

nav .nav-inner {
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 60px;
}

nav .logo {
  font-weight: 700;
  font-size: 1.1rem;
  background: linear-gradient(135deg, var(--primary-light), var(--accent));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  letter-spacing: -0.5px;
}

nav ul {
  list-style: none;
  display: flex;
  gap: 8px;
}

nav a {
  color: var(--text-muted);
  text-decoration: none;
  font-size: 0.85rem;
  font-weight: 500;
  padding: 6px 14px;
  border-radius: 8px;
  transition: all 0.2s;
}

nav a:hover {
  color: var(--text);
  background: var(--surface);
}


/* ==========================================================
   5. Buttons
   ========================================================== */

.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 10px 22px;
  border-radius: 10px;
  font-size: 0.9rem;
  font-weight: 600;
  text-decoration: none;
  transition: all 0.25s;
  cursor: pointer;
  border: none;
}

.btn svg { width: 18px; height: 18px; }

.btn-primary {
  background: linear-gradient(135deg, var(--primary), var(--primary-dark));
  color: #fff;
  box-shadow: 0 4px 20px rgba(99,102,241,0.3);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 30px rgba(99,102,241,0.4);
}

.btn-outline {
  background: transparent;
  color: var(--text);
  border: 1px solid var(--border);
}

.btn-outline:hover {
  background: var(--surface);
  border-color: var(--primary);
}


/* ==========================================================
   6. Hero
   ========================================================== */

.hero {
  padding: 160px 0 60px;
  text-align: center;
  position: relative;
}

.hero::before {
  content: '';
  position: absolute;
  top: 60px;
  left: 50%;
  transform: translateX(-50%);
  width: 600px;
  height: 600px;
  background: radial-gradient(circle, rgba(99,102,241,0.12) 0%, transparent 70%);
  pointer-events: none;
}

.hero .badge {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 6px 16px;
  border-radius: 999px;
  background: rgba(99,102,241,0.1);
  border: 1px solid rgba(99,102,241,0.2);
  font-size: 0.8rem;
  font-weight: 500;
  color: var(--primary-light);
  margin-bottom: 28px;
}

.badge .dot {
  width: 6px; height: 6px;
  border-radius: 50%;
  background: var(--success);
  animation: pulse 2s infinite;
}

@keyframes pulse {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.4; }
}

.hero h1 {
  font-size: clamp(2.2rem, 5vw, 3.2rem);
  font-weight: 800;
  letter-spacing: -1.5px;
  line-height: 1.15;
  margin-bottom: 20px;
  background: linear-gradient(135deg, #fff 0%, #c7d2fe 50%, var(--accent-light) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.hero .subtitle {
  font-size: 1.05rem;
  color: var(--text-muted);
  max-width: 750px;
  margin: 0 auto 16px;
  font-weight: 400;
  line-height: 1.6;
}

.hero .authors {
  font-size: 0.95rem;
  color: var(--text-dim);
  margin-bottom: 12px;
}

.hero .keywords {
  font-size: 0.78rem;
  color: var(--text-dim);
  margin-bottom: 32px;
  display: flex;
  justify-content: center;
  flex-wrap: wrap;
  gap: 8px;
}

.hero .kw-tag {
  padding: 3px 10px;
  border-radius: 6px;
  background: rgba(99,102,241,0.08);
  border: 1px solid rgba(99,102,241,0.15);
  color: var(--text-dim);
  font-size: 0.72rem;
  font-weight: 500;
}

.hero .links {
  display: flex;
  justify-content: center;
  gap: 12px;
  flex-wrap: wrap;
}


/* ==========================================================
   7. Key Highlights (stat cards)
   ========================================================== */

.highlights {
  padding: 0 0 80px;
}

.highlights-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 16px;
}

.highlight-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px;
  text-align: center;
  position: relative;
  overflow: hidden;
  transition: border-color 0.3s, transform 0.3s;
}

.highlight-card:hover {
  border-color: rgba(99,102,241,0.3);
  transform: translateY(-2px);
}

.highlight-card::before {
  content: '';
  position: absolute;
  top: 0; left: 0; right: 0;
  height: 2px;
  background: linear-gradient(90deg, var(--primary), var(--accent));
}

.highlight-card .stat-value {
  font-size: 2rem;
  font-weight: 800;
  font-family: 'JetBrains Mono', monospace;
  background: linear-gradient(135deg, var(--primary-light), var(--accent-light));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  line-height: 1.2;
  margin-bottom: 6px;
}

.highlight-card .stat-label {
  font-size: 0.78rem;
  font-weight: 600;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 1px;
}

.highlight-card .stat-detail {
  font-size: 0.72rem;
  color: var(--text-dim);
  margin-top: 4px;
}


/* ==========================================================
   8. Sections (common)
   ========================================================== */

section { padding: 80px 0; }

.section-label {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 2px;
  color: var(--primary-light);
  margin-bottom: 12px;
}

.section-label::before {
  content: '';
  width: 20px; height: 2px;
  background: var(--primary);
  border-radius: 2px;
}

.section-title {
  font-size: clamp(1.6rem, 3vw, 2.2rem);
  font-weight: 700;
  letter-spacing: -0.8px;
  margin-bottom: 16px;
}

.section-desc {
  color: var(--text-muted);
  max-width: 700px;
  margin-bottom: 48px;
  font-size: 1rem;
}


/* ==========================================================
   9. Abstract
   ========================================================== */

.abstract-card {
  background: linear-gradient(135deg, var(--bg-card), var(--bg-card-alt));
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 40px;
  position: relative;
  overflow: hidden;
}

.abstract-card::before {
  content: '';
  position: absolute;
  top: 0; left: 0; right: 0;
  height: 3px;
  background: linear-gradient(90deg, var(--primary), var(--accent));
}

.abstract-card p {
  font-size: 1rem;
  line-height: 1.85;
  color: var(--text-muted);
  text-align: justify;
}


/* ==========================================================
   10. Method Overview
   ========================================================== */

.method-steps {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
  margin-top: 12px;
}

.method-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 28px 24px;
  position: relative;
  overflow: hidden;
}

.method-card .step-num {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 32px; height: 32px;
  border-radius: 8px;
  background: linear-gradient(135deg, var(--primary), var(--accent));
  color: #fff;
  font-size: 0.82rem;
  font-weight: 700;
  margin-bottom: 16px;
}

.method-card h3 {
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: 10px;
}

.method-card p {
  font-size: 0.88rem;
  color: var(--text-muted);
  line-height: 1.65;
}

.method-card .formula {
  margin-top: 12px;
  padding: 10px 14px;
  background: var(--bg-card-alt);
  border: 1px solid var(--border);
  border-radius: 8px;
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.78rem;
  color: var(--accent-light);
  overflow-x: auto;
}


/* ==========================================================
   10b. Augmentation Simulation
   ========================================================== */

.aug-samples {
  display: flex;
  flex-direction: column;
  gap: 28px;
}

.aug-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
}

.aug-card .aug-header {
  padding: 18px 24px;
  border-bottom: 1px solid var(--border);
  display: flex;
  align-items: center;
  gap: 10px;
}

.aug-card .aug-header h3 {
  font-size: 0.95rem;
  font-weight: 600;
}

.aug-card .aug-text {
  padding: 14px 24px;
  background: var(--bg-card-alt);
  border-bottom: 1px solid var(--border);
  font-size: 0.88rem;
  color: var(--text);
  font-style: italic;
  line-height: 1.6;
}

.aug-card .aug-text .label {
  font-size: 0.7rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 1.5px;
  color: var(--text-dim);
  margin-bottom: 4px;
  font-style: normal;
}

.aug-audio-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1px;
  background: var(--border);
}

.aug-audio-cell {
  background: var(--bg-card);
  padding: 16px 20px;
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.aug-audio-cell .aug-audio-label {
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 1px;
}

.aug-audio-cell .aug-audio-label.original { color: var(--text-muted); }
.aug-audio-cell .aug-audio-label.repeat   { color: #ef4444; }
.aug-audio-cell .aug-audio-label.skip     { color: var(--warning); }

.aug-audio-cell audio {
  width: 100%;
  height: 40px;
  border-radius: 8px;
}

.aug-audio-cell .aug-desc {
  font-size: 0.72rem;
  color: var(--text-dim);
  line-height: 1.5;
}

.aug-legend {
  margin-top: 20px;
  padding: 20px 24px;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.aug-legend-item {
  display: flex;
  align-items: flex-start;
  gap: 12px;
  font-size: 0.85rem;
  color: var(--text-muted);
  line-height: 1.5;
}

.aug-legend-item .aug-tag {
  flex-shrink: 0;
  padding: 3px 10px;
  border-radius: 6px;
  font-size: 0.72rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.aug-tag.repeat-tag {
  background: rgba(239,68,68,0.1);
  color: #ef4444;
  border: 1px solid rgba(239,68,68,0.2);
}

.aug-tag.skip-tag {
  background: rgba(245,158,11,0.1);
  color: var(--warning);
  border: 1px solid rgba(245,158,11,0.2);
}

@media (max-width: 768px) {
  .aug-audio-grid { grid-template-columns: 1fr; }
}


/* ==========================================================
   11. Results & Tables
   ========================================================== */

.results-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 32px;
}

.result-block {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
}

.result-block .block-header {
  padding: 20px 28px;
  border-bottom: 1px solid var(--border);
  display: flex;
  align-items: center;
  gap: 10px;
}

.result-block .block-header h3 {
  font-size: 1rem;
  font-weight: 600;
}

.result-block .block-header .icon {
  width: 32px; height: 32px;
  border-radius: 8px;
  background: rgba(99,102,241,0.1);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--primary-light);
  font-size: 0.9rem;
}

.table-scroll {
  overflow-x: auto;
}

table {
  width: 100%;
  border-collapse: collapse;
}

thead th {
  text-align: left;
  padding: 14px 16px;
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 1px;
  color: var(--text-dim);
  background: var(--bg-card-alt);
  border-bottom: 1px solid var(--border);
  white-space: nowrap;
}

tbody td {
  padding: 12px 16px;
  border-bottom: 1px solid rgba(45,45,74,0.5);
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.82rem;
  white-space: nowrap;
}

tbody td:first-child {
  font-family: 'Inter', sans-serif;
  font-size: 0.88rem;
}

tbody tr:last-child td { border-bottom: none; }
tbody tr:hover { background: rgba(99,102,241,0.03); }

.row-ours { background: rgba(99,102,241,0.06) !important; }
.row-ours td { color: var(--primary-light); font-weight: 600; }
.best-val { color: var(--accent-light); font-weight: 700; }
.second-val { text-decoration: underline; text-underline-offset: 3px; }

.table-sep td {
  padding: 0;
  height: 2px;
  border-bottom: 2px solid var(--border) !important;
}


/* ==========================================================
   12. Figure Grid (CER curves)
   ========================================================== */

.figure-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
  padding: 24px;
}

.figure-grid img {
  width: 100%;
  border-radius: 8px;
  border: 1px solid var(--border);
}

.figure-grid .fig-label {
  text-align: center;
  font-size: 0.78rem;
  color: var(--text-dim);
  margin-top: 6px;
}

.figure-container {
  padding: 24px;
  display: flex;
  justify-content: center;
  align-items: center;
  min-height: 200px;
}

.figure-container img {
  max-width: 100%;
  border-radius: 8px;
}

.figure-placeholder {
  width: 100%;
  min-height: 200px;
  border: 2px dashed var(--border);
  border-radius: 8px;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  color: var(--text-dim);
  gap: 8px;
  font-size: 0.85rem;
}

.figure-placeholder svg {
  width: 40px; height: 40px;
  opacity: 0.4;
}

.figure-caption {
  padding: 0 28px 20px;
  font-size: 0.85rem;
  color: var(--text-dim);
  text-align: center;
  line-height: 1.5;
}


/* ==========================================================
   13. Audio Demos & Tabs
   ========================================================== */

.demo-tabs {
  display: flex;
  gap: 8px;
  margin-bottom: 32px;
  flex-wrap: wrap;
}

.demo-tab {
  padding: 8px 20px;
  border-radius: 10px;
  background: var(--bg-card);
  border: 1px solid var(--border);
  color: var(--text-muted);
  font-size: 0.85rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.2s;
  user-select: none;
}

.demo-tab:hover {
  border-color: var(--primary);
  color: var(--text);
}

.demo-tab.active {
  background: linear-gradient(135deg, var(--primary), var(--primary-dark));
  border-color: var(--primary);
  color: #fff;
  box-shadow: 0 4px 16px rgba(99,102,241,0.25);
}

/* Benchmark group heading */
.demo-group {
  transition: opacity 0.3s, max-height 0.3s;
}

.demo-group.hidden {
  display: none;
}

.demo-group-header {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 24px;
  padding-bottom: 12px;
  border-bottom: 1px solid var(--border);
}

.demo-group-header h3 {
  font-size: 1.1rem;
  font-weight: 700;
}

.demo-group-note {
  margin: -16px 0 24px;
  padding: 8px 14px;
  background: rgba(245,158,11,0.06);
  border-left: 3px solid var(--warning);
  border-radius: 0 6px 6px 0;
  font-size: 0.8rem;
  font-weight: 500;
  color: var(--warning);
  line-height: 1.5;
}

.demo-group-badge {
  padding: 4px 12px;
  border-radius: 6px;
  font-size: 0.7rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.demo-group-badge.seed {
  background: rgba(99,102,241,0.1);
  color: var(--primary-light);
  border: 1px solid rgba(99,102,241,0.2);
}

.demo-group-badge.z5en {
  background: rgba(16,185,129,0.1);
  color: var(--success);
  border: 1px solid rgba(16,185,129,0.2);
}

.demo-group-badge.z5ko {
  background: rgba(6,182,212,0.1);
  color: var(--accent-light);
  border: 1px solid rgba(6,182,212,0.2);
}

.demo-samples {
  display: flex;
  flex-direction: column;
  gap: 28px;
  margin-bottom: 48px;
}

.demo-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
  transition: border-color 0.3s;
}

.demo-card:hover { border-color: rgba(99,102,241,0.3); }

.demo-header {
  padding: 16px 24px;
  border-bottom: 1px solid var(--border);
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.demo-header h3 {
  font-size: 0.95rem;
  font-weight: 600;
  display: flex;
  align-items: center;
  gap: 10px;
}

.demo-number {
  width: 28px; height: 28px;
  border-radius: 8px;
  background: linear-gradient(135deg, var(--primary), var(--accent));
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.78rem;
  font-weight: 700;
  color: #fff;
  flex-shrink: 0;
}

.demo-text {
  padding: 14px 24px;
  background: var(--bg-card-alt);
  border-bottom: 1px solid var(--border);
}

.demo-text .label {
  font-size: 0.7rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 1.5px;
  color: var(--text-dim);
  margin-bottom: 6px;
}

.demo-text p {
  font-size: 0.92rem;
  color: var(--text);
  font-style: italic;
  line-height: 1.6;
}

.audio-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 1px;
  background: var(--border);
}

@media (max-width: 960px) {
  .audio-grid { grid-template-columns: repeat(2, 1fr); }
}

@media (max-width: 520px) {
  .audio-grid { grid-template-columns: 1fr; }
}

.audio-cell {
  background: var(--bg-card);
  padding: 16px 20px;
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.audio-cell .audio-label {
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.5px;
  color: var(--text-dim);
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  gap: 5px;
}

.audio-cell .audio-label.ref { color: var(--text-muted); }
.audio-cell .audio-label.baseline { color: var(--warning); }
.audio-cell .audio-label.contrastive { color: var(--success); }
.audio-cell .audio-label.ours { color: var(--accent-light); }

.audio-cell audio {
  width: 100%;
  height: 40px;
  border-radius: 8px;
}

.audio-cell audio::-webkit-media-controls-panel {
  background: var(--surface);
}

/* Transcript + WER display */
.audio-meta {
  margin-top: 2px;
  padding: 8px 10px;
  background: var(--bg-card-alt);
  border: 1px solid var(--border);
  border-radius: 8px;
  font-size: 0.72rem;
  line-height: 1.5;
}

.audio-meta .transcript-label {
  color: var(--text-dim);
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.5px;
  font-size: 0.65rem;
}

.audio-meta .transcript-text {
  display: block;
  color: var(--text-muted);
  margin-top: 2px;
  font-style: italic;
  word-break: break-word;
}

.wer-badge {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  padding: 2px 8px;
  border-radius: 4px;
  font-family: 'JetBrains Mono', monospace;
  font-size: 0.68rem;
  font-weight: 600;
  flex-shrink: 0;
  white-space: nowrap;
}

.wer-badge.good {
  background: rgba(16,185,129,0.1);
  color: var(--success);
  border: 1px solid rgba(16,185,129,0.15);
}

.wer-badge.mid {
  background: rgba(245,158,11,0.1);
  color: var(--warning);
  border: 1px solid rgba(245,158,11,0.15);
}

.wer-badge.bad {
  background: rgba(239,68,68,0.1);
  color: #ef4444;
  border: 1px solid rgba(239,68,68,0.15);
}


/* ==========================================================
   14. Download / Evaluation Sets
   ========================================================== */

.download-cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  gap: 20px;
}

.download-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 32px;
  display: flex;
  flex-direction: column;
  gap: 16px;
  transition: all 0.3s;
  position: relative;
  overflow: hidden;
}

.download-card::before {
  content: '';
  position: absolute;
  inset: 0;
  background: linear-gradient(135deg, rgba(99,102,241,0.05), transparent);
  opacity: 0;
  transition: opacity 0.3s;
  pointer-events: none;
}

.download-card:hover::before { opacity: 1; }

.download-card:hover {
  border-color: rgba(99,102,241,0.3);
  transform: translateY(-2px);
}

.download-card .dl-icon {
  width: 48px; height: 48px;
  border-radius: 12px;
  background: rgba(99,102,241,0.1);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--primary-light);
}

.download-card h3 { font-size: 1.05rem; font-weight: 600; }
.download-card p  { font-size: 0.88rem; color: var(--text-muted); line-height: 1.6; }

.download-card .meta {
  font-size: 0.78rem;
  color: var(--text-dim);
  display: flex;
  gap: 16px;
}

.download-card .meta span {
  display: flex;
  align-items: center;
  gap: 4px;
}

.download-card .btn-download {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 10px 20px;
  border-radius: 10px;
  background: var(--surface);
  color: var(--text);
  font-size: 0.85rem;
  font-weight: 600;
  text-decoration: none;
  border: 1px solid var(--border);
  transition: all 0.2s;
  width: fit-content;
  position: relative;
  z-index: 1;
}

.download-card .btn-download:hover {
  background: var(--primary);
  border-color: var(--primary);
}


/* ==========================================================
   15. Footer
   ========================================================== */

footer {
  padding: 40px 0;
  border-top: 1px solid var(--border);
  text-align: center;
  color: var(--text-dim);
  font-size: 0.82rem;
}

footer a {
  color: var(--primary-light);
  text-decoration: none;
}


/* ==========================================================
   16. Utilities (divider, animations)
   ========================================================== */

.divider {
  height: 1px;
  background: linear-gradient(90deg, transparent, var(--border), transparent);
  margin: 0;
}

.fade-in {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

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


/* ==========================================================
   17. Responsive
   ========================================================== */

@media (max-width: 900px) {
  .method-steps { grid-template-columns: 1fr; }
  .figure-grid { grid-template-columns: 1fr; }
}

@media (max-width: 768px) {
  .hero { padding: 120px 0 40px; }
  .abstract-card { padding: 24px; }
  .audio-grid { grid-template-columns: 1fr 1fr; }
  nav ul { gap: 2px; }
  nav a { padding: 6px 10px; font-size: 0.78rem; }
  .highlights-grid { grid-template-columns: repeat(2, 1fr); }
}

@media (max-width: 480px) {
  .audio-grid { grid-template-columns: 1fr; }
  .download-cards { grid-template-columns: 1fr; }
  .highlights-grid { grid-template-columns: 1fr; }
}