:root {
  --color-primary: #0d6efd;
  --color-primary-dark: #0b5ed7;
  --color-secondary: #06b6d4;
  --color-accent: #f59e0b;
  --color-text: #1f2937;
  --color-text-light: #6b7280;
  --color-bg: #ffffff;
  --color-bg-alt: #f8fafc;
  --color-bg-dark: #0f172a;
  --color-border: #e5e7eb;
  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -2px rgba(0, 0, 0, 0.1);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -4px rgba(0, 0, 0, 0.1);
  --radius: 0.75rem;
  --max-width: 1200px;
  --header-height: 4rem;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: "Noto Sans SC", "PingFang SC", "Microsoft YaHei", sans-serif;
  color: var(--color-text);
  line-height: 1.7;
  background: var(--color-bg);
}

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

a:hover {
  text-decoration: underline;
}

img {
  max-width: 100%;
  height: auto;
}

.container {
  width: 100%;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 1.5rem;
}

/* Header */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: rgba(255, 255, 255, 0.95);
  backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--color-border);
}

.nav-wrapper {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: var(--header-height);
}

.logo {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  color: var(--color-text);
  font-weight: 700;
  font-size: 1.1rem;
}

.logo:hover {
  text-decoration: none;
}

.logo-icon {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 2.25rem;
  height: 2.25rem;
  border-radius: 0.5rem;
  background: linear-gradient(135deg, var(--color-primary), var(--color-secondary));
  color: #fff;
  font-size: 0.85rem;
  font-weight: 700;
}

.logo-text {
  display: none;
}

@media (min-width: 640px) {
  .logo-text {
    display: inline;
  }
}

.main-nav {
  position: relative;
}

.nav-toggle {
  display: flex;
  flex-direction: column;
  justify-content: center;
  gap: 0.3rem;
  width: 2.5rem;
  height: 2.5rem;
  padding: 0.5rem;
  background: transparent;
  border: 1px solid var(--color-border);
  border-radius: 0.375rem;
  cursor: pointer;
}

.nav-toggle span {
  display: block;
  height: 2px;
  background: var(--color-text);
  border-radius: 2px;
  transition: transform 0.2s, opacity 0.2s;
}

.nav-toggle span:nth-child(1) { width: 100%; }
.nav-toggle span:nth-child(2) { width: 75%; }
.nav-toggle span:nth-child(3) { width: 50%; }

.nav-menu {
  position: absolute;
  top: calc(var(--header-height) - 1rem);
  right: 0;
  min-width: 12rem;
  margin: 0;
  padding: 0.5rem;
  list-style: none;
  background: #fff;
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  box-shadow: var(--shadow-lg);
  opacity: 0;
  visibility: hidden;
  transform: translateY(-0.5rem);
  transition: opacity 0.2s, transform 0.2s, visibility 0.2s;
}

.nav-menu.open {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

.nav-menu a {
  display: block;
  padding: 0.625rem 1rem;
  color: var(--color-text);
  border-radius: 0.375rem;
  font-weight: 500;
}

.nav-menu a:hover {
  background: var(--color-bg-alt);
  text-decoration: none;
}

.nav-menu a.active {
  color: var(--color-primary);
  background: rgba(13, 110, 253, 0.08);
}

/* Dropdown navigation */
.has-dropdown {
  position: relative;
}

.has-dropdown > a::after {
  content: "▼";
  display: inline-block;
  margin-left: 0.35rem;
  font-size: 0.65rem;
  vertical-align: middle;
}

.has-dropdown::before {
  content: "";
  position: absolute;
  top: 100%;
  left: 0;
  width: 100%;
  height: 0.75rem;
  background: transparent;
}

.dropdown-menu {
  display: none;
  margin: 0.25rem 0 0;
  padding: 0.5rem;
  list-style: none;
  background: #fff;
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  box-shadow: var(--shadow-lg);
}

.dropdown-menu a {
  padding: 0.5rem 0.875rem;
  font-size: 0.9375rem;
  color: var(--color-text);
  border-radius: 0.375rem;
}

.dropdown-menu a:hover {
  background: var(--color-bg-alt);
}

.has-dropdown.open .dropdown-menu,
.has-dropdown:hover .dropdown-menu {
  display: block;
}

.site-header-dark .dropdown-menu {
  background: rgba(26, 11, 46, 0.98);
  border-color: rgba(255, 255, 255, 0.15);
}

.site-header-dark .dropdown-menu a {
  color: #e2e8f0;
}

.site-header-dark .dropdown-menu a:hover {
  background: rgba(255, 255, 255, 0.1);
  color: #fff;
}

.site-header-dark {
  background: rgba(26, 11, 46, 0.95);
  border-bottom-color: rgba(255, 255, 255, 0.1);
}

.site-header-dark .logo {
  color: #fff;
}

.site-header-dark .nav-toggle {
  border-color: rgba(255, 255, 255, 0.3);
}

.site-header-dark .nav-toggle span {
  background: #fff;
}

.site-header-dark .nav-menu a {
  color: #e2e8f0;
}

.site-header-dark .nav-menu a:hover {
  background: rgba(255, 255, 255, 0.1);
  color: #fff;
}

.site-header-dark .nav-menu a.active {
  color: #ff4ecd;
  background: rgba(255, 255, 255, 0.12);
}

.site-header-dark .nav-menu.open {
  background: rgba(26, 11, 46, 0.98);
  border-color: rgba(255, 255, 255, 0.15);
}

@media (min-width: 900px) {
  .nav-toggle {
    display: none;
  }

  .nav-menu {
    position: static;
    display: flex;
    gap: 0.25rem;
    min-width: auto;
    padding: 0;
    background: transparent;
    border: none;
    box-shadow: none;
    opacity: 1;
    visibility: visible;
    transform: none;
  }

  .has-dropdown > a::after {
    margin-left: 0.25rem;
  }

  .dropdown-menu {
    position: absolute;
    top: calc(100% + 0.5rem);
    left: 0;
    min-width: 13rem;
    margin: 0;
  }

  .has-dropdown:hover .dropdown-menu,
  .has-dropdown.open .dropdown-menu {
    display: block;
  }
}

/* Hero */
.hero {
  position: relative;
  display: flex;
  align-items: center;
  min-height: calc(100vh - var(--header-height));
  padding: 4rem 0;
  background: linear-gradient(135deg, #f0f9ff 0%, #e0f2fe 50%, #f5f3ff 100%);
  overflow: hidden;
}

.hero-decoration {
  position: absolute;
  inset: 0;
  background:
    radial-gradient(circle at 20% 30%, rgba(13, 110, 253, 0.12) 0%, transparent 40%),
    radial-gradient(circle at 80% 70%, rgba(6, 182, 212, 0.12) 0%, transparent 40%);
  pointer-events: none;
}

.hero-content {
  position: relative;
  z-index: 1;
  max-width: 800px;
}

.hero-label {
  display: inline-block;
  margin: 0 0 1rem;
  padding: 0.375rem 1rem;
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--color-primary-dark);
  background: rgba(13, 110, 253, 0.1);
  border-radius: 999px;
}

.hero h1 {
  margin: 0 0 1.25rem;
  font-size: clamp(2rem, 5vw, 3.5rem);
  font-weight: 700;
  line-height: 1.2;
  color: #0f172a;
}

.hero-subtitle {
  margin: 0 0 2rem;
  font-size: clamp(1rem, 2vw, 1.25rem);
  color: var(--color-text-light);
  max-width: 640px;
}

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

.hero-banner {
  display: inline-flex;
  flex-direction: column;
  gap: 0.25rem;
  margin-bottom: 2rem;
  padding: 1rem 1.5rem;
  background: rgba(255, 255, 255, 0.9);
  border: 1px solid rgba(13, 110, 253, 0.2);
  border-radius: var(--radius);
  box-shadow: var(--shadow-sm);
}

.hero-banner strong {
  color: var(--color-primary-dark);
  font-size: 1rem;
}

.hero-banner span {
  color: var(--color-text-light);
  font-size: 0.9375rem;
}

.hero-current {
  background: linear-gradient(135deg, #240b36 0%, #b5179e 35%, #1a0b2e 70%, #0f0c29 100%);
}

.hero-current .hero-decoration {
  background:
    radial-gradient(circle at 15% 15%, rgba(255, 78, 205, 0.25) 0%, transparent 35%),
    radial-gradient(circle at 85% 85%, rgba(67, 97, 238, 0.2) 0%, transparent 35%),
    repeating-linear-gradient(-45deg, rgba(255, 255, 255, 0.03) 0px, rgba(255, 255, 255, 0.03) 1px, transparent 1px, transparent 30px);
}

.hero-history {
  background: linear-gradient(135deg, #fff7ed 0%, #ffedd5 50%, #fef3c7 100%);
}

.hero-history .hero-decoration {
  background:
    radial-gradient(circle at 20% 30%, rgba(245, 158, 11, 0.12) 0%, transparent 40%),
    radial-gradient(circle at 80% 70%, rgba(249, 115, 22, 0.1) 0%, transparent 40%);
}

.hero-history .hero-label {
  color: #92400e;
  background: rgba(245, 158, 11, 0.12);
}

.hero-history h1,
.hero-history .hero-subtitle {
  color: #431407;
}

.hero-current h1,
.hero-current .hero-subtitle {
  color: #fff;
}

.hero-current .hero-label {
  color: #ffd6f5;
  background: rgba(255, 78, 205, 0.18);
  border: 1px solid rgba(255, 78, 205, 0.4);
}

.hero-current .hero-banner {
  background: rgba(15, 12, 41, 0.45);
  border-color: rgba(255, 78, 205, 0.3);
  box-shadow: 0 8px 32px rgba(0, 0, 0, 0.25);
}

.hero-current .hero-banner strong {
  color: #ff4ecd;
}

.hero-current .hero-banner span {
  color: #f3e8ff;
}

.hero-current .btn-primary {
  background: linear-gradient(135deg, #ff4ecd, #b5179e);
  box-shadow: 0 4px 14px rgba(255, 78, 205, 0.35);
}

.hero-current .btn-primary:hover {
  box-shadow: 0 6px 20px rgba(255, 78, 205, 0.45);
}

.hero-current .btn-outline {
  color: #fff;
  background: rgba(255, 255, 255, 0.08);
  border-color: rgba(255, 78, 205, 0.5);
}

.hero-current .btn-outline:hover {
  background: rgba(255, 78, 205, 0.15);
}

.hero-content-split {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 3rem;
  align-items: center;
  max-width: var(--max-width);
}

.hero-content-split .hero-text {
  max-width: 720px;
}

.hero-content-split .hero-cta {
  display: flex;
  flex-direction: column;
  align-items: flex-end;
  justify-content: center;
}

.hero-content-split .hero-actions {
  flex-direction: column;
  gap: 1rem;
}

.hero-content-split .hero-actions .btn {
  width: 12rem;
}

@media (max-width: 900px) {
  .hero-content-split {
    grid-template-columns: 1fr;
    gap: 2rem;
  }

  .hero-content-split .hero-cta {
    align-items: flex-start;
  }

  .hero-content-split .hero-actions {
    flex-direction: row;
  }

  .hero-content-split .hero-actions .btn {
    width: auto;
  }
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0.875rem 1.75rem;
  font-size: 1rem;
  font-weight: 500;
  border-radius: 0.5rem;
  transition: background 0.2s, color 0.2s, box-shadow 0.2s;
}

.btn:hover {
  text-decoration: none;
}

.btn-primary {
  color: #fff;
  background: linear-gradient(135deg, var(--color-primary), var(--color-primary-dark));
  box-shadow: 0 4px 14px rgba(13, 110, 253, 0.35);
}

.btn-primary:hover {
  box-shadow: 0 6px 20px rgba(13, 110, 253, 0.45);
}

.btn-outline {
  color: var(--color-primary-dark);
  background: #fff;
  border: 1px solid var(--color-primary);
}

.btn-outline:hover {
  background: rgba(13, 110, 253, 0.05);
}

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

.section-header {
  text-align: center;
  margin-bottom: 3rem;
}

.section-header h2 {
  margin: 0 0 0.75rem;
  font-size: clamp(1.75rem, 4vw, 2.5rem);
  color: #0f172a;
}

.section-header.light h2,
.section-header.light .section-lead {
  color: #fff;
}

.section-lead {
  margin: 0;
  font-size: 1.125rem;
  color: var(--color-text-light);
}

.section-cta {
  text-align: center;
  margin-top: 3rem;
}

/* About */
.about {
  background: var(--color-bg);
}

.about-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 1.5rem;
}

.about-card {
  padding: 2rem;
  background: var(--color-bg-alt);
  border-radius: var(--radius);
  border: 1px solid var(--color-border);
}

.about-card h3 {
  margin: 0 0 1rem;
  font-size: 1.25rem;
  color: var(--color-primary-dark);
}

.about-card p {
  margin: 0;
  color: var(--color-text-light);
}

.about-card.highlight {
  background: linear-gradient(135deg, var(--color-primary), var(--color-secondary));
  color: #fff;
  border: none;
}

.about-card.highlight h3,
.about-card.highlight p {
  color: #fff;
}

.about-card .note {
  margin-top: 0.75rem;
  font-size: 0.875rem;
  color: var(--color-text-light);
}

.about-card.highlight .note {
  color: rgba(255, 255, 255, 0.85);
}

/* History / Timeline */
.history {
  background: var(--color-bg-dark);
}

.timeline {
  display: grid;
  gap: 1.5rem;
}

.timeline-item {
  display: grid;
  grid-template-columns: auto 1fr;
  gap: 1.5rem;
  padding: 2rem;
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid rgba(255, 255, 255, 0.1);
  border-radius: var(--radius);
  backdrop-filter: blur(4px);
  transition: transform 0.2s, background 0.2s;
}

.timeline-item:hover {
  background: rgba(255, 255, 255, 0.08);
  transform: translateY(-2px);
}

.timeline-marker {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  width: 4rem;
  height: 4rem;
  font-size: 1.25rem;
  font-weight: 700;
  line-height: 1.2;
  color: #fff;
  background: linear-gradient(135deg, var(--color-primary), var(--color-secondary));
  border-radius: 50%;
}

.timeline-marker small {
  font-size: 0.65rem;
  font-weight: 500;
  opacity: 0.9;
}

.timeline-content h3 {
  margin: 0 0 0.75rem;
  font-size: 1.375rem;
  color: #fff;
}

.timeline-content p {
  margin: 0 0 1rem;
  color: rgba(255, 255, 255, 0.8);
}

.meta-list {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem 1.5rem;
  margin: 0 0 1rem;
  padding: 0;
  list-style: none;
  font-size: 0.9375rem;
  color: rgba(255, 255, 255, 0.75);
}

.meta-list li {
  position: relative;
}

.meta-list li:not(:last-child)::after {
  content: "·";
  position: absolute;
  right: -1rem;
  color: rgba(255, 255, 255, 0.4);
}

.link-arrow {
  display: inline-flex;
  align-items: center;
  gap: 0.25rem;
  font-weight: 500;
  color: var(--color-secondary);
}

.link-arrow::after {
  content: "→";
  transition: transform 0.2s;
}

.link-arrow:hover::after {
  transform: translateX(4px);
}

@media (max-width: 640px) {
  .timeline-item {
    grid-template-columns: 1fr;
  }

  .timeline-marker {
    width: 3.5rem;
    height: 3.5rem;
    font-size: 1rem;
  }
}

/* Details */
.details {
  background: var(--color-bg-alt);
}

.detail-card {
  margin-bottom: 2rem;
  background: #fff;
  border-radius: var(--radius);
  box-shadow: var(--shadow-md);
  overflow: hidden;
}

.detail-card:last-child {
  margin-bottom: 0;
}

.detail-card.upcoming {
  border: 2px dashed var(--color-border);
  box-shadow: none;
}

.detail-header {
  padding: 2rem 2rem 1.5rem;
  border-bottom: 1px solid var(--color-border);
}

.detail-year {
  display: inline-block;
  margin-bottom: 0.75rem;
  padding: 0.25rem 0.75rem;
  font-size: 0.875rem;
  font-weight: 700;
  color: #fff;
  background: linear-gradient(135deg, var(--color-primary), var(--color-secondary));
  border-radius: 0.375rem;
}

.detail-header h3 {
  margin: 0 0 0.5rem;
  font-size: 1.5rem;
  color: #0f172a;
}

.detail-meta {
  margin: 0;
  color: var(--color-text-light);
  font-size: 0.9375rem;
}

.detail-body {
  padding: 2rem;
}

.detail-body p {
  margin: 0 0 1.25rem;
}

.detail-body h4 {
  margin: 1.75rem 0 0.75rem;
  font-size: 1.125rem;
  color: #0f172a;
}

.detail-body ul {
  margin: 0 0 1.25rem;
  padding-left: 1.25rem;
}

.detail-body ul ul {
  margin-top: 0.5rem;
  margin-bottom: 0.75rem;
}

.detail-body li {
  margin-bottom: 0.5rem;
}

.detail-summary {
  padding: 1rem 1.25rem;
  background: var(--color-bg-alt);
  border-left: 4px solid var(--color-secondary);
  border-radius: 0 0.5rem 0.5rem 0;
  color: var(--color-text-light);
}

.agenda-list {
  margin: 0;
  padding: 0;
  list-style: none;
}

.agenda-list li {
  display: flex;
  gap: 1.5rem;
  padding: 1.25rem 1.5rem;
  margin-bottom: 1rem;
  background: var(--color-bg-alt);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
}

.agenda-list li:last-child {
  margin-bottom: 0;
}

.agenda-time {
  flex-shrink: 0;
  width: 7rem;
  font-weight: 700;
  color: var(--color-primary-dark);
}

.agenda-content {
  flex: 1;
  min-width: 0;
}

.agenda-title {
  display: block;
  font-weight: 700;
  color: #0f172a;
  margin-bottom: 0.25rem;
}

.agenda-speaker {
  display: block;
  color: var(--color-text-light);
  font-size: 0.9375rem;
  line-height: 1.6;
}

.forum-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 1.5rem;
}

.forum-grid .detail-card {
  margin-bottom: 0;
  height: 100%;
}

.tag-list {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin: 0 0 1.25rem;
  padding: 0;
  list-style: none;
}

.tag-list li {
  padding: 0.375rem 0.75rem;
  background: var(--color-bg-alt);
  border: 1px solid var(--color-border);
  border-radius: 999px;
  font-size: 0.875rem;
  color: var(--color-text-light);
}

@media (max-width: 640px) {
  .agenda-list li {
    flex-direction: column;
    gap: 0.5rem;
    padding: 1rem;
  }

  .agenda-time {
    width: auto;
  }
}

/* Venue Map */
.venue-map {
  margin: 0 0 1.5rem;
  text-align: center;
}

.venue-map img {
  width: 100%;
  max-width: 100%;
  height: auto;
  border-radius: var(--radius);
  box-shadow: var(--shadow-md);
}

.venue-map figcaption {
  margin-top: 1rem;
  font-size: 0.9375rem;
  color: var(--color-text-light);
}

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

.legend-item {
  padding: 1rem;
  background: var(--color-bg-alt);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
}

.legend-item strong {
  display: block;
  margin-bottom: 0.25rem;
  color: #0f172a;
}

.legend-item span {
  font-size: 0.9375rem;
  color: var(--color-text-light);
}

/* Organizers */
.organizers {
  background: linear-gradient(135deg, #0f172a 0%, #1e293b 100%);
}

.organizer-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 1.5rem;
}

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

.organizer-card {
  padding: 1.75rem;
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid rgba(255, 255, 255, 0.1);
  border-radius: var(--radius);
}

.organizer-card h3 {
  margin: 0 0 1rem;
  font-size: 1.125rem;
  color: var(--color-secondary);
}

.organizer-card ul {
  margin: 0;
  padding: 0;
  list-style: none;
}

.organizer-card li {
  margin-bottom: 0.5rem;
  color: rgba(255, 255, 255, 0.85);
}

/* Contact */
.contact {
  background: var(--color-bg);
  text-align: center;
}

.contact-content {
  max-width: 640px;
  margin: 0 auto;
}

.contact-info {
  margin: 1.5rem 0;
  padding: 1.25rem;
  background: var(--color-bg-alt);
  border-radius: var(--radius);
  text-align: left;
}

.contact-info p {
  margin: 0 0 0.5rem;
}

.contact-info p:last-child {
  margin-bottom: 0;
}

.contact-info a {
  color: var(--color-primary);
  font-weight: 500;
}

.contact-note {
  font-size: 0.875rem;
  color: var(--color-text-light);
}

/* Footer */
.site-footer {
  padding: 2rem 0;
  text-align: center;
  background: var(--color-bg-dark);
  color: rgba(255, 255, 255, 0.6);
  font-size: 0.875rem;
}

.site-footer p {
  margin: 0;
}

/* Utilities */
@media (max-width: 640px) {
  .section {
    padding: 3rem 0;
  }

  .hero {
    min-height: auto;
    padding: 3rem 0;
  }

  .detail-header,
  .detail-body {
    padding: 1.5rem;
  }

  .organizer-grid-3 {
    grid-template-columns: 1fr;
  }
}