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

:root {
  --color-primary: #1a3a5c;
  --color-primary-light: #2a5a8c;
  --color-accent: #e8913a;
  --color-accent-light: #f4a854;
  --color-bg: #ffffff;
  --color-bg-alt: #f6f8fb;
  --color-text: #2d3748;
  --color-text-light: #64748b;
  --color-border: #e2e8f0;
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-serif: 'Source Serif 4', Georgia, 'Times New Roman', serif;
  --max-width: 960px;
  --radius: 10px;
}

html {
  scroll-behavior: smooth;
  scroll-padding-top: 80px;
}

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

a {
  color: var(--color-primary-light);
  text-decoration: none;
  transition: color 0.2s;
}

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

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

/* ===== Navigation ===== */
.navbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  background: transparent;
  transition: background 0.3s, box-shadow 0.3s;
}

.navbar.scrolled {
  background: rgba(255, 255, 255, 0.97);
  box-shadow: 0 1px 12px rgba(0, 0, 0, 0.08);
  backdrop-filter: blur(12px);
}

.nav-container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
}

.nav-brand {
  display: flex;
  align-items: center;
  gap: 12px;
}

.nav-sigmetrics {
  display: flex;
  align-items: center;
  background: rgba(255, 255, 255, 0.95);
  border-radius: 4px;
  padding: 3px 8px;
  transition: background 0.3s;
}

.nav-sigmetrics img {
  height: 20px;
  width: auto;
  display: block;
}

.nav-sigmetrics:hover {
  background: #fff;
}

.navbar.scrolled .nav-sigmetrics {
  background: transparent;
  padding: 0;
}

.nav-logo {
  font-weight: 700;
  font-size: 1.05rem;
  color: #fff;
  letter-spacing: -0.02em;
  transition: color 0.3s;
}

.navbar.scrolled .nav-logo {
  color: var(--color-primary);
}

.nav-links {
  list-style: none;
  display: flex;
  gap: 32px;
}

.nav-links a {
  color: rgba(255, 255, 255, 0.85);
  font-size: 0.9rem;
  font-weight: 500;
  transition: color 0.2s;
}

.nav-links a:hover {
  color: #fff;
}

.navbar.scrolled .nav-links a {
  color: var(--color-text-light);
}

.navbar.scrolled .nav-links a:hover {
  color: var(--color-primary);
}

.nav-toggle {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  flex-direction: column;
  gap: 5px;
  padding: 4px;
}

.nav-toggle span {
  display: block;
  width: 24px;
  height: 2px;
  background: #fff;
  border-radius: 2px;
  transition: background 0.3s;
}

.navbar.scrolled .nav-toggle span {
  background: var(--color-text);
}

/* ===== Hero ===== */
.hero {
  position: relative;
  min-height: 520px;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: 120px 24px 80px;
  background: linear-gradient(135deg, #0f2744 0%, #1a4a7a 50%, #2a6aa0 100%);
  overflow: hidden;
}

.hero::before {
  content: '';
  position: absolute;
  top: -50%;
  left: -50%;
  width: 200%;
  height: 200%;
  background: radial-gradient(ellipse at 30% 50%, rgba(232, 145, 58, 0.12) 0%, transparent 60%),
              radial-gradient(ellipse at 70% 30%, rgba(255, 255, 255, 0.06) 0%, transparent 50%);
  pointer-events: none;
}

.hero-content {
  position: relative;
  z-index: 1;
  max-width: 720px;
}

.hero-badge {
  display: inline-block;
  padding: 6px 18px;
  border: 1px solid rgba(255, 255, 255, 0.25);
  border-radius: 100px;
  color: rgba(255, 255, 255, 0.9);
  font-size: 0.85rem;
  font-weight: 500;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  margin-bottom: 24px;
}

.hero-badge a {
  color: rgba(255, 255, 255, 0.9);
  text-decoration: underline;
  text-underline-offset: 3px;
  text-decoration-color: rgba(255, 255, 255, 0.35);
}

.hero-badge a:hover {
  color: #fff;
  text-decoration-color: rgba(255, 255, 255, 0.7);
}

.hero-title {
  font-family: var(--font-serif);
  font-size: 2.3rem;
  font-weight: 700;
  color: #fff;
  line-height: 1.2;
  margin-bottom: 32px;
  letter-spacing: -0.02em;
  white-space: nowrap;
}

.hero-details {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 24px;
}

.hero-detail-item {
  display: flex;
  align-items: center;
  gap: 8px;
  color: rgba(255, 255, 255, 0.8);
  font-size: 0.95rem;
}

.hero-detail-item svg {
  flex-shrink: 0;
  opacity: 0.7;
}

.hero-organizers {
  margin-top: 28px;
  font-size: 0.95rem;
  color: rgba(255, 255, 255, 0.75);
}

.hero-organizers a {
  color: rgba(255, 255, 255, 0.95);
  text-decoration: underline;
  text-underline-offset: 3px;
  text-decoration-color: rgba(255, 255, 255, 0.35);
}

.hero-organizers a:hover {
  color: #fff;
  text-decoration-color: rgba(255, 255, 255, 0.7);
}

/* ===== Sections ===== */
.section {
  padding: 80px 0;
}

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

.section-title {
  font-family: var(--font-serif);
  font-size: 2rem;
  font-weight: 700;
  color: var(--color-primary);
  margin-bottom: 40px;
  letter-spacing: -0.02em;
}

/* ===== Overview ===== */
.overview-content {
  max-width: 760px;
}

.overview-content p {
  margin-bottom: 16px;
  font-size: 1.05rem;
  color: var(--color-text);
}

.overview-content p:last-child {
  margin-bottom: 0;
}

.link {
  color: var(--color-primary-light);
  text-decoration: underline;
  text-underline-offset: 3px;
  text-decoration-color: rgba(42, 90, 140, 0.3);
  transition: text-decoration-color 0.2s, color 0.2s;
}

.link:hover {
  color: var(--color-accent);
  text-decoration-color: var(--color-accent);
}

/* ===== Sponsors ===== */
.sponsors-grid {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 64px;
  flex-wrap: wrap;
}

.sponsor-item {
  display: inline-flex;
  flex-direction: row;
  align-items: center;
  flex-wrap: nowrap;
  gap: 16px;
  text-decoration: none;
  transition: opacity 0.2s, transform 0.2s;
}

.sponsor-item:hover {
  opacity: 0.75;
  transform: translateY(-2px);
}

.sponsor-item img {
  height: 56px;
  width: auto;
  flex-shrink: 0;
}

.sponsor-logo-dark {
  filter: brightness(0) saturate(100%) invert(14%) sepia(45%) saturate(2000%) hue-rotate(190deg) brightness(90%);
}

.sponsor-label {
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--color-primary);
  text-align: left;
  white-space: nowrap;
  border-left: 2px solid var(--color-border);
  padding-left: 16px;
}

/* ===== Schedule ===== */
.schedule-note {
  font-size: 0.9rem;
  color: var(--color-text-light);
  font-style: italic;
  margin-bottom: 24px;
  margin-top: -16px;
}

.schedule {
  max-width: 760px;
}

.schedule-block {
  display: flex;
  gap: 24px;
  padding: 20px 0;
  border-bottom: 1px solid var(--color-border);
}

.schedule-block:last-child {
  border-bottom: none;
}

.schedule-time {
  flex-shrink: 0;
  width: 160px;
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--color-primary);
  padding-top: 2px;
}

.schedule-info {
  flex: 1;
}

.schedule-label {
  font-size: 1.05rem;
  font-weight: 600;
  color: var(--color-text);
  margin-bottom: 4px;
}

.schedule-break .schedule-label {
  color: var(--color-text-light);
  font-weight: 500;
  font-style: italic;
}

.schedule-speaker {
  font-size: 0.9rem;
  color: var(--color-text-light);
  margin-bottom: 2px;
}

.schedule-talk-title {
  font-size: 0.9rem;
  color: var(--color-text);
  font-style: italic;
}

.schedule-talks {
  list-style: none;
  padding: 0;
  margin-top: 8px;
}

.schedule-talks li {
  font-size: 0.93rem;
  padding: 4px 0;
  color: var(--color-text);
  line-height: 1.5;
}

.schedule-talks li strong {
  font-weight: 600;
}

/* ===== Speakers ===== */
.speakers-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 24px;
}

.speaker-card {
  display: flex;
  gap: 20px;
  padding: 24px;
  background: var(--color-bg-alt);
  border-radius: var(--radius);
  border: 1px solid var(--color-border);
  transition: box-shadow 0.2s, border-color 0.2s;
}

.speaker-card:hover {
  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.06);
  border-color: rgba(26, 58, 92, 0.15);
}

.speaker-avatar {
  flex-shrink: 0;
  width: 56px;
  height: 56px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--color-primary), var(--color-primary-light));
  color: #fff;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 1rem;
  letter-spacing: 0.05em;
}

.speaker-body {
  flex: 1;
  min-width: 0;
}

.speaker-name {
  font-size: 1.1rem;
  font-weight: 600;
  margin-bottom: 2px;
}

.speaker-name a {
  color: var(--color-primary);
}

.speaker-name a:hover {
  color: var(--color-accent);
}

.badge-tentative {
  display: inline-block;
  font-size: 0.65rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  color: var(--color-accent);
  background: rgba(232, 145, 58, 0.1);
  border: 1px solid rgba(232, 145, 58, 0.3);
  border-radius: 100px;
  padding: 2px 10px;
  vertical-align: middle;
  margin-left: 6px;
}

.speaker-affiliation {
  font-size: 0.9rem;
  color: var(--color-text-light);
  margin-bottom: 6px;
}

.speaker-talk-title {
  font-size: 0.95rem;
  font-weight: 500;
  color: var(--color-text);
  margin-bottom: 8px;
}

.speaker-abstract {
  margin-top: 8px;
}

.speaker-abstract summary {
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--color-primary-light);
  cursor: pointer;
  user-select: none;
  padding: 4px 0;
}

.speaker-abstract summary:hover {
  color: var(--color-accent);
}

.speaker-abstract p {
  margin-top: 8px;
  font-size: 0.9rem;
  color: var(--color-text-light);
  line-height: 1.65;
}

/* ===== Important Dates ===== */
.dates-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

.date-card {
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 32px 24px;
  text-align: center;
  transition: box-shadow 0.2s, transform 0.2s;
}

.date-card:hover {
  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.06);
  transform: translateY(-2px);
}

.date-icon {
  color: var(--color-accent);
  margin-bottom: 16px;
}

.date-label {
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--color-text);
  margin-bottom: 8px;
}

.date-value {
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--color-primary);
}

/* ===== Organizers ===== */
.organizers-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 32px;
  text-align: center;
}

.organizer-card {
  display: flex;
  flex-direction: column;
  align-items: center;
}

.organizer-avatar {
  width: 72px;
  height: 72px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--color-primary), var(--color-primary-light));
  color: #fff;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 1.2rem;
  letter-spacing: 0.05em;
  margin-bottom: 16px;
}

.organizer-photo {
  width: 120px;
  height: 120px;
  border-radius: 50%;
  object-fit: cover;
  margin-bottom: 16px;
  border: 3px solid var(--color-border);
  transition: transform 0.2s, border-color 0.2s;
}

.organizer-card:hover .organizer-photo {
  transform: scale(1.05);
  border-color: var(--color-primary-light);
}

.organizer-card h3 {
  font-size: 1.05rem;
  font-weight: 600;
  margin-bottom: 4px;
}

.organizer-card h3 a {
  color: var(--color-primary);
}

.organizer-card h3 a:hover {
  color: var(--color-accent);
}

.organizer-card p {
  font-size: 0.9rem;
  color: var(--color-text-light);
}

/* ===== Footer ===== */
.footer {
  background: var(--color-primary);
  color: rgba(255, 255, 255, 0.85);
  text-align: center;
  padding: 40px 24px;
  font-size: 0.9rem;
}

.footer a {
  color: var(--color-accent-light);
}

.footer a:hover {
  color: #fff;
}

.footer-sub {
  margin-top: 8px;
  font-size: 0.85rem;
  color: rgba(255, 255, 255, 0.6);
}

/* ===== Responsive ===== */
@media (max-width: 768px) {
  .hero {
    min-height: 420px;
    padding: 100px 20px 60px;
  }

  .hero-title {
    font-size: 1.5rem;
    white-space: normal;
  }

  .hero-details {
    flex-direction: column;
    align-items: center;
    gap: 12px;
  }

  .section {
    padding: 56px 0;
  }

  .section-title {
    font-size: 1.6rem;
    margin-bottom: 28px;
  }

  .nav-toggle {
    display: flex;
  }

  .nav-links {
    display: none;
    position: absolute;
    top: 64px;
    left: 0;
    right: 0;
    background: #fff;
    flex-direction: column;
    padding: 16px 24px;
    gap: 12px;
    box-shadow: 0 8px 24px rgba(0, 0, 0, 0.1);
  }

  .nav-links.open {
    display: flex;
  }

  .nav-links a {
    color: var(--color-text) !important;
    font-size: 1rem;
  }

  .schedule-block {
    flex-direction: column;
    gap: 4px;
  }

  .schedule-time {
    width: auto;
  }

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

  .organizers-grid {
    grid-template-columns: 1fr;
    gap: 24px;
  }

  .speaker-card {
    flex-direction: column;
    align-items: flex-start;
  }
}

@media (max-width: 480px) {
  .hero-title {
    font-size: 1.25rem;
  }

  .hero-badge {
    font-size: 0.75rem;
  }
}