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

:root {
  --color-primary: #1a56db;
  --color-primary-dark: #1e40af;
  --color-primary-light: #dbeafe;
  --color-accent: #f59e0b;
  --color-text: #1e293b;
  --color-text-light: #64748b;
  --color-text-muted: #94a3b8;
  --color-bg: #ffffff;
  --color-bg-alt: #f1f5f9;
  --color-border: #e2e8f0;
  --color-hero-bg: #0f172a;
  --font-family: "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto,
    "Helvetica Neue", Arial, sans-serif;
  --max-width: 960px;
}

html {
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-family);
  color: var(--color-text);
  line-height: 1.7;
  background: var(--color-bg);
}

.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 1.5rem;
}

/* ===== Navigation ===== */
.navbar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  background: rgba(15, 23, 42, 0.95);
  backdrop-filter: blur(12px);
  z-index: 1000;
  transition: background 0.3s;
}

.navbar.scrolled {
  background: rgba(15, 23, 42, 0.98);
  box-shadow: 0 1px 12px rgba(0, 0, 0, 0.15);
}

.nav-container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 60px;
}

.logo {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  text-decoration: none;
  color: #ffffff;
}

.logo-img {
  height: 36px;
  width: auto;
}

.logo-text {
  display: flex;
  flex-direction: column;
  line-height: 1.2;
}

.logo-title {
  font-size: calc(36px * 0.7);
  font-weight: 800;
  letter-spacing: -0.02em;
}

.logo-location {
  font-size: 0.65rem;
  font-weight: 500;
  color: #94a3b8;
  letter-spacing: 0.02em;
}

.nav-links {
  display: flex;
  list-style: none;
  gap: 1.6rem;
}

.nav-links a {
  text-decoration: none;
  color: #cbd5e1;
  font-weight: 500;
  font-size: 0.85rem;
  transition: color 0.2s;
}

.nav-links a:hover,
.nav-links a.active {
  color: #ffffff;
}

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

.nav-toggle span {
  display: block;
  width: 22px;
  height: 2px;
  background: #cbd5e1;
  border-radius: 2px;
  transition: transform 0.3s, opacity 0.3s;
}

/* ===== Hero ===== */
.hero {
  position: relative;
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 520px;
  text-align: center;
  background: linear-gradient(135deg, #0f172a 0%, #1e3a5f 50%, #1a56db 100%);
  padding: 120px 0 80px;
  overflow: hidden;
}

.hero-overlay {
  position: absolute;
  inset: 0;
  background:
    radial-gradient(ellipse at 20% 80%, rgba(59, 130, 246, 0.15) 0%, transparent 50%),
    radial-gradient(ellipse at 80% 20%, rgba(139, 92, 246, 0.1) 0%, transparent 50%);
  pointer-events: none;
}

.hero-content {
  position: relative;
  z-index: 1;
}

.hero-label {
  display: inline-block;
  background: rgba(255, 255, 255, 0.1);
  border: 1px solid rgba(255, 255, 255, 0.15);
  color: #93c5fd;
  font-size: 0.85rem;
  font-weight: 600;
  padding: 0.35rem 1rem;
  border-radius: 100px;
  margin-bottom: 1.5rem;
  letter-spacing: 0.02em;
}

.hero h1 {
  font-size: clamp(1.8rem, 4vw, 2.8rem);
  font-weight: 800;
  color: #ffffff;
  line-height: 1.2;
  max-width: 700px;
  margin: 0 auto 1.5rem;
  letter-spacing: -0.02em;
}

.hero-meta {
  display: flex;
  justify-content: center;
  gap: 2rem;
  margin-bottom: 2rem;
  flex-wrap: wrap;
}

.hero-meta-item {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  color: #94a3b8;
  font-size: 0.95rem;
}

.hero-meta-item svg {
  flex-shrink: 0;
}

.hero-actions {
  display: flex;
  justify-content: center;
  gap: 1rem;
  flex-wrap: wrap;
}

/* ===== Buttons ===== */
.btn {
  display: inline-block;
  padding: 0.7rem 1.8rem;
  text-decoration: none;
  border: none;
  border-radius: 8px;
  font-size: 0.9rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.2s;
  font-family: var(--font-family);
}

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

.btn-primary:hover {
  background: var(--color-primary-dark);
  transform: translateY(-1px);
  box-shadow: 0 4px 12px rgba(26, 86, 219, 0.3);
}

.btn-outline {
  background: transparent;
  color: #cbd5e1;
  border: 1px solid rgba(255, 255, 255, 0.2);
}

.btn-outline:hover {
  background: rgba(255, 255, 255, 0.08);
  border-color: rgba(255, 255, 255, 0.35);
  color: #fff;
}

.btn:active {
  transform: scale(0.98);
}

/* ===== Sections ===== */
.section {
  padding: 5rem 0;
}

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

.section-title {
  font-size: 1.75rem;
  font-weight: 800;
  margin-bottom: 0.5rem;
  text-align: center;
  letter-spacing: -0.02em;
  color: var(--color-text);
}

.section-subtitle {
  text-align: center;
  color: var(--color-text-muted);
  font-size: 0.9rem;
  margin-bottom: 2rem;
}

/* ===== About ===== */
.about-content {
  max-width: 720px;
  margin: 1.5rem auto 0;
}

.about-content p {
  color: var(--color-text-light);
  margin-bottom: 1rem;
  font-size: 0.95rem;
}

/* ===== Schedule ===== */
.schedule-table {
  max-width: 720px;
  margin: 0 auto;
}

.schedule-row {
  display: flex;
  gap: 1.5rem;
  padding: 0.9rem 1rem;
  border-bottom: 1px solid var(--color-border);
  align-items: flex-start;
}

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

.schedule-header {
  font-weight: 700;
  font-size: 0.8rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--color-text-muted);
  border-bottom: 2px solid var(--color-border);
}

.schedule-time {
  flex: 0 0 140px;
  font-size: 0.9rem;
  color: var(--color-text-light);
  font-variant-numeric: tabular-nums;
}

.schedule-event {
  flex: 1;
  font-size: 0.9rem;
}

.schedule-speaker {
  display: block;
  color: var(--color-text-muted);
  font-size: 0.85rem;
  margin-top: 0.15rem;
}

/* ===== Papers ===== */
.papers-list {
  max-width: 720px;
  margin: 1.5rem auto 0;
  display: flex;
  flex-direction: column;
  gap: 0;
}

.paper-card {
  padding: 1.25rem 0;
  border-bottom: 1px solid var(--color-border);
}

.paper-card:last-child {
  border-bottom: none;
}

.paper-title {
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: 0.3rem;
  color: var(--color-text);
  line-height: 1.4;
}

.paper-authors {
  font-size: 0.85rem;
  color: var(--color-text-muted);
  margin-bottom: 0.5rem;
}

.paper-links {
  display: flex;
  gap: 0.75rem;
}

.paper-link {
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--color-primary);
  text-decoration: none;
  padding: 0.2rem 0.6rem;
  border: 1px solid var(--color-primary);
  border-radius: 4px;
  transition: all 0.2s;
}

.paper-link:hover {
  background: var(--color-primary);
  color: #fff;
}

/* ===== Speakers ===== */
.speakers-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
  gap: 1.5rem;
  max-width: 800px;
  margin: 1.5rem auto 0;
}

.speaker-card {
  text-align: center;
  text-decoration: none;
  color: inherit;
  display: block;
  padding: 1rem 0.5rem;
  border-radius: 10px;
  transition: background 0.2s, transform 0.2s;
}

.speaker-card:hover {
  background: var(--color-bg-alt);
  transform: translateY(-2px);
}

.speaker-photo {
  width: 80px;
  height: 80px;
  border-radius: 50%;
  object-fit: cover;
  margin: 0 auto 0.75rem;
  display: block;
}

.speaker-status {
  display: inline-block;
  font-size: 0.72rem;
  font-weight: 600;
  padding: 0.2rem 0.6rem;
  border-radius: 100px;
  margin-top: 0.5rem;
  letter-spacing: 0.02em;
}

.speaker-status.confirmed {
  background: #dcfce7;
  color: #166534;
}

.speaker-status.tbc {
  background: #fef9c3;
  color: #854d0e;
}

/* ===== Call for Papers ===== */
.cfp-content {
  max-width: 720px;
  margin: 1.5rem auto 0;
}

.cfp-content p {
  font-size: 0.95rem;
  color: var(--color-text-light);
  margin-bottom: 1rem;
}

.cfp-content h3 {
  font-size: 1.15rem;
  font-weight: 700;
  margin: 2rem 0 0.75rem;
  color: var(--color-text);
}

.topic-list {
  list-style: none;
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0.5rem 2rem;
  margin: 1rem 0 1.5rem;
}

.topic-list li {
  font-size: 0.9rem;
  color: var(--color-text-light);
  padding-left: 1.2rem;
  position: relative;
}

.topic-list li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.55em;
  width: 6px;
  height: 6px;
  background: var(--color-primary);
  border-radius: 50%;
}

/* ===== Key Dates ===== */
.dates-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 1rem;
  max-width: 720px;
  margin: 1.5rem auto 0;
}

.date-card {
  background: var(--color-bg-alt);
  border: 1px solid var(--color-border);
  border-radius: 10px;
  padding: 1.25rem 1.5rem;
  text-align: center;
}

.date-label {
  font-size: 0.8rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  color: var(--color-text-muted);
  margin-bottom: 0.5rem;
}

.date-value {
  font-size: 1rem;
  font-weight: 700;
  color: var(--color-text);
}

.date-value.highlight {
  color: var(--color-primary);
}

.dates-note {
  text-align: center;
  font-size: 0.85rem;
  color: var(--color-text-muted);
  margin-top: 1.25rem;
}

/* ===== Organizers ===== */
.organizers-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
  gap: 1.5rem;
  max-width: 720px;
  margin: 1.5rem auto 0;
}

.organizer-card {
  text-align: center;
}

.organizer-avatar {
  width: 80px;
  height: 80px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--color-primary), #6366f1);
  color: #fff;
  font-weight: 700;
  font-size: 1.1rem;
  display: flex;
  align-items: center;
  justify-content: center;
  margin: 0 auto 0.75rem;
}

.organizer-link {
  text-decoration: none;
  color: inherit;
  display: block;
  padding: 1rem 0.5rem;
  border-radius: 10px;
  transition: background 0.2s, transform 0.2s;
}

.organizer-link:hover {
  background: var(--color-bg);
  transform: translateY(-2px);
}

.organizer-link *,
.organizer-link:hover * {
  text-decoration: none;
}

.organizer-name {
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--color-text);
}

.organizer-affiliation {
  font-size: 0.82rem;
  color: var(--color-text-muted);
  margin-top: 0.15rem;
}

.subsection-title {
  text-align: center;
  font-size: 1rem;
  font-weight: 700;
  color: var(--color-text);
  margin: 3rem 0 1rem;
}

.institutions {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 0.75rem;
  max-width: 720px;
  margin: 0 auto;
}

.institution {
  font-size: 0.85rem;
  color: var(--color-text-light);
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  padding: 0.4rem 1rem;
  border-radius: 100px;
}

/* ===== Footer ===== */
.footer {
  text-align: center;
  padding: 2.5rem 0;
  background: var(--color-hero-bg);
  color: #94a3b8;
  font-size: 0.85rem;
}

.footer a {
  color: #93c5fd;
  text-decoration: none;
}

.footer a:hover {
  color: #bfdbfe;
  text-decoration: underline;
}

.footer-copy {
  margin-top: 0.5rem;
  font-size: 0.8rem;
  color: #475569;
}

/* ===== Responsive ===== */
@media (max-width: 768px) {
  .nav-toggle {
    display: flex;
  }

  .nav-links {
    display: none;
    position: absolute;
    top: 60px;
    left: 0;
    right: 0;
    flex-direction: column;
    background: rgba(15, 23, 42, 0.98);
    border-bottom: 1px solid rgba(255, 255, 255, 0.08);
    padding: 1rem 1.5rem;
    gap: 0.75rem;
  }

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

  .hero {
    min-height: auto;
    padding: 100px 0 60px;
  }

  .hero h1 {
    font-size: 1.6rem;
  }

  .hero-meta {
    flex-direction: column;
    align-items: center;
    gap: 0.75rem;
  }

  .schedule-time {
    flex: 0 0 100px;
    font-size: 0.8rem;
  }

  .topic-list {
    grid-template-columns: 1fr;
  }

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

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

@media (max-width: 480px) {
  .dates-grid {
    grid-template-columns: 1fr;
  }

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

  .schedule-row {
    flex-direction: column;
    gap: 0.25rem;
  }

  .schedule-time {
    flex: unset;
    font-weight: 600;
    color: var(--color-primary);
  }
}