/* ========================================
   GenEval-DR Paper Website
   Modern · Minimalistic
   ======================================== */

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

:root {
  --color-bg: #fafafa;
  --color-bg-alt: #f2f2f4;
  --color-surface: #ffffff;
  --color-text: #1a1a2e;
  --color-text-secondary: #555568;
  --color-text-muted: #8888a0;
  --color-border: #e4e4ec;
  --color-accent: #5b5bf0;
  --color-accent-light: #e8e8fd;
  --color-accent-dark: #4040c0;
  --color-gradient-start: #5b5bf0;
  --color-gradient-end: #8b5cf6;
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 20px;
  --shadow-sm: 0 1px 3px rgba(0,0,0,0.04), 0 1px 2px rgba(0,0,0,0.06);
  --shadow-md: 0 4px 16px rgba(0,0,0,0.06), 0 1px 4px rgba(0,0,0,0.04);
  --shadow-lg: 0 12px 40px rgba(0,0,0,0.08);
  --transition: 0.25s cubic-bezier(0.4, 0, 0.2, 1);
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', monospace;
  --max-width: 960px;
}

html {
  scroll-behavior: smooth;
  font-size: 16px;
}

body {
  font-family: var(--font-sans);
  color: var(--color-text);
  background: var(--color-bg);
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

img, video {
  max-width: 100%;
  display: block;
}

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

a:hover {
  color: var(--color-accent-dark);
}

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

/* --- Navbar --- */
.navbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  padding: 16px 0;
  transition: background var(--transition), box-shadow var(--transition), padding var(--transition);
}

.navbar.scrolled {
  background: rgba(250, 250, 250, 0.92);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  box-shadow: 0 1px 0 var(--color-border);
  padding: 10px 0;
}

.nav-content {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.nav-logo {
  font-weight: 700;
  font-size: 1.1rem;
  color: var(--color-text);
  letter-spacing: -0.02em;
}

.nav-logo:hover {
  color: var(--color-accent);
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 28px;
}

.nav-links a {
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--color-text-secondary);
  transition: color var(--transition);
}

.nav-links a:hover {
  color: var(--color-text);
}

.nav-btn {
  padding: 6px 16px;
  border-radius: var(--radius-sm);
  background: var(--color-text);
  color: #fff !important;
  font-size: 0.85rem;
  transition: background var(--transition), transform var(--transition);
}

.nav-btn:hover {
  background: var(--color-accent);
  color: #fff !important;
  transform: translateY(-1px);
}

/* --- Hero --- */
.hero {
  position: relative;
  padding: 160px 0 100px;
  overflow: hidden;
}

.hero-bg-accent {
  position: absolute;
  top: -180px;
  right: -120px;
  width: 500px;
  height: 500px;
  background: radial-gradient(circle, rgba(91, 91, 240, 0.06) 0%, transparent 70%);
  pointer-events: none;
}

.hero-container {
  position: relative;
}

.hero-badge {
  display: inline-block;
  font-size: 0.8rem;
  font-weight: 600;
  letter-spacing: 0.04em;
  color: var(--color-accent);
  background: var(--color-accent-light);
  padding: 6px 16px;
  border-radius: 100px;
  margin-bottom: 28px;
}

.hero-title {
  font-size: clamp(2rem, 5vw, 3rem);
  font-weight: 700;
  line-height: 1.15;
  letter-spacing: -0.03em;
  color: var(--color-text);
  max-width: 760px;
  margin-bottom: 20px;
}

.gradient-text {
  background: linear-gradient(135deg, var(--color-gradient-start), var(--color-gradient-end));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero-authors {
  font-size: 1.05rem;
  color: var(--color-text);
  margin: 0 0 6px;
  font-weight: 500;
}

.hero-affiliation {
  font-size: 0.95rem;
  color: var(--color-text-secondary);
  margin: 0 0 28px;
}

.hero-subtitle {
  font-size: 1.125rem;
  color: var(--color-text-secondary);
  max-width: 600px;
  line-height: 1.7;
  margin-bottom: 36px;
}

.hero-actions {
  display: flex;
  gap: 14px;
  flex-wrap: wrap;
}

/* --- Buttons --- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 12px 24px;
  border-radius: var(--radius-sm);
  font-weight: 600;
  font-size: 0.9rem;
  transition: all var(--transition);
  cursor: pointer;
  border: none;
  text-decoration: none;
}

.btn-primary {
  background: var(--color-text);
  color: #fff;
}

.btn-primary:hover {
  background: var(--color-accent);
  color: #fff;
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
}

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

.btn-secondary:hover {
  border-color: var(--color-accent);
  color: var(--color-accent);
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
}

/* --- Sections --- */
.section {
  padding: 100px 0;
}

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

.section-label {
  font-size: 0.8rem;
  font-weight: 600;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--color-accent);
  margin-bottom: 12px;
}

.section-title {
  font-size: clamp(1.5rem, 3.5vw, 2.25rem);
  font-weight: 700;
  letter-spacing: -0.02em;
  margin-bottom: 16px;
  color: var(--color-text);
}

.section-desc {
  font-size: 1.05rem;
  color: var(--color-text-secondary);
  max-width: 560px;
  margin-bottom: 48px;
}

/* --- Insight Grid --- */
.insight-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
  margin-bottom: 48px;
}

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

.insight-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
}

.insight-icon {
  width: 52px;
  height: 52px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-sm);
  background: var(--color-accent-light);
  color: var(--color-accent);
  margin-bottom: 20px;
}

.insight-card h3 {
  font-size: 1.05rem;
  font-weight: 600;
  margin-bottom: 10px;
  letter-spacing: -0.01em;
}

.insight-card p {
  font-size: 0.92rem;
  color: var(--color-text-secondary);
  line-height: 1.65;
}

/* --- Abstract Details --- */
.abstract-details {
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  background: var(--color-surface);
  overflow: hidden;
}

.abstract-details summary {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 16px 24px;
  font-weight: 600;
  font-size: 0.95rem;
  cursor: pointer;
  color: var(--color-text-secondary);
  transition: background var(--transition), color var(--transition);
  list-style: none;
}

.abstract-details summary::-webkit-details-marker {
  display: none;
}

.abstract-details summary:hover {
  background: var(--color-bg-alt);
  color: var(--color-text);
}

.abstract-details summary svg {
  transition: transform var(--transition);
}

.abstract-details[open] summary svg {
  transform: rotate(180deg);
}

.abstract-text {
  padding: 8px 24px 24px;
  border-top: 1px solid var(--color-border);
}

.abstract-text p {
  font-size: 0.95rem;
  color: var(--color-text-secondary);
  margin-bottom: 12px;
  line-height: 1.75;
}

.abstract-text p:last-child {
  margin-bottom: 0;
}

/* --- Demo Grid --- */
.demo-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 40px;
}

.demo-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  overflow: hidden;
  transition: transform var(--transition), box-shadow var(--transition);
}

.demo-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
}

.demo-video-wrapper {
  position: relative;
  width: 100%;
}

.demo-video-placeholder {
  aspect-ratio: 16 / 9;
  background: linear-gradient(145deg, #e8e8f0, #d8d8e8);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 16px;
  cursor: pointer;
  transition: background var(--transition);
}

.demo-video-placeholder:hover {
  background: linear-gradient(145deg, #dde0f0, #ccd0e8);
}

.play-icon {
  width: 72px;
  height: 72px;
  border-radius: 50%;
  background: rgba(255, 255, 255, 0.9);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--color-accent);
  box-shadow: var(--shadow-md);
  transition: transform var(--transition), box-shadow var(--transition);
}

.demo-video-placeholder:hover .play-icon {
  transform: scale(1.08);
  box-shadow: var(--shadow-lg);
}

.placeholder-label {
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--color-text-muted);
  letter-spacing: 0.02em;
}

.demo-video-wrapper video {
  width: 100%;
  display: block;
}

.demo-info {
  padding: 28px 32px 32px;
}

.demo-info h3 {
  font-size: 1.2rem;
  font-weight: 600;
  margin-bottom: 10px;
  letter-spacing: -0.01em;
}

.demo-info p {
  font-size: 0.95rem;
  color: var(--color-text-secondary);
  line-height: 1.7;
}

/* --- Open Source Banner --- */
.oss-banner {
  display: flex;
  align-items: flex-start;
  gap: 24px;
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-left: 4px solid var(--color-accent);
  border-radius: var(--radius-md);
  padding: 32px 36px;
  transition: transform var(--transition), box-shadow var(--transition);
}

.oss-banner:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
}

.oss-icon {
  flex-shrink: 0;
  width: 56px;
  height: 56px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: var(--radius-sm);
  background: var(--color-accent-light);
  color: var(--color-accent);
}

.oss-content h3 {
  font-size: 1.1rem;
  font-weight: 600;
  margin-bottom: 8px;
  letter-spacing: -0.01em;
}

.oss-content p {
  font-size: 0.95rem;
  color: var(--color-text-secondary);
  line-height: 1.7;
}

/* --- Footer --- */
.footer {
  padding: 32px 0;
  border-top: 1px solid var(--color-border);
}

.footer-content {
  text-align: center;
}

.footer-content p {
  font-size: 0.85rem;
  color: var(--color-text-muted);
}

/* --- Animation --- */
.animate-in {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.6s cubic-bezier(0.4, 0, 0.2, 1), transform 0.6s cubic-bezier(0.4, 0, 0.2, 1);
}

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

/* Stagger delay for insight cards */
.insight-card:nth-child(2).animate-in {
  transition-delay: 0.1s;
}
.insight-card:nth-child(3).animate-in {
  transition-delay: 0.2s;
}

/* Stagger delay for demo cards */
.demo-card:nth-child(2).animate-in {
  transition-delay: 0.1s;
}

/* --- Responsive --- */
@media (max-width: 768px) {
  .hero {
    padding: 120px 0 72px;
  }

  .insight-grid {
    grid-template-columns: 1fr;
    gap: 16px;
  }

  .section {
    padding: 72px 0;
  }

  .nav-links {
    gap: 16px;
  }

  .oss-banner {
    flex-direction: column;
    gap: 16px;
    padding: 24px;
  }

  .demo-info {
    padding: 20px 24px 24px;
  }
}

@media (max-width: 480px) {
  .hero-title {
    font-size: 1.75rem;
  }

  .hero-actions {
    flex-direction: column;
  }

  .btn {
    justify-content: center;
  }

  .nav-links a:not(.nav-btn) {
    display: none;
  }
}