:root {
  --navy: #1C3260;
  --navy-dark: #132244;
  --navy-light: #264a8c;
  --blue: #57B4E5;
  --blue-dark: #3A9FD6;
  --blue-light: #8ACFEE;
  --white: #FFFFFF;
  --off-white: #F4F7FB;
  --gray-100: #EEF1F6;
  --gray-200: #D5DDE8;
  --gray-400: #8A9BB5;
  --gray-600: #4A5A72;
  --text: #1C2E4A;
  --text-light: #5A6E88;
  --radius: 8px;
  --radius-lg: 16px;
  --shadow: 0 2px 12px rgba(28, 50, 96, 0.10);
  --shadow-lg: 0 8px 32px rgba(28, 50, 96, 0.15);
  --transition: 0.2s ease;
  --max-width: 1200px;
}

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

html { scroll-behavior: smooth; }

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
  color: var(--text);
  background: var(--white);
  line-height: 1.6;
  font-size: 16px;
}

a { color: var(--blue); text-decoration: none; transition: color var(--transition); }
a:hover { color: var(--blue-dark); }

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

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

/* ── BUTTONS ──────────────────────────────── */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 12px 28px;
  border-radius: var(--radius);
  font-weight: 600;
  font-size: 0.95rem;
  cursor: pointer;
  border: 2px solid transparent;
  transition: all var(--transition);
  white-space: nowrap;
}

.btn-primary {
  background: var(--blue);
  color: var(--white);
  border-color: var(--blue);
}
.btn-primary:hover {
  background: var(--blue-dark);
  border-color: var(--blue-dark);
  color: var(--white);
}

.btn-outline {
  background: transparent;
  color: var(--white);
  border-color: var(--white);
}
.btn-outline:hover {
  background: var(--white);
  color: var(--navy);
}

.btn-navy {
  background: var(--navy);
  color: var(--white);
  border-color: var(--navy);
}
.btn-navy:hover {
  background: var(--navy-dark);
  border-color: var(--navy-dark);
  color: var(--white);
}

/* ── NAV ──────────────────────────────────── */
.site-nav {
  position: sticky;
  top: 0;
  z-index: 100;
  background: var(--navy);
  border-bottom: 3px solid var(--blue);
  padding: 0 24px;
}

.nav-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 68px;
}

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

.nav-logo img {
  height: 44px;
  width: auto;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 4px;
  list-style: none;
}

.nav-links a {
  color: var(--gray-200);
  padding: 8px 14px;
  border-radius: var(--radius);
  font-size: 0.9rem;
  font-weight: 500;
  transition: all var(--transition);
}

.nav-links a:hover,
.nav-links a.active {
  color: var(--white);
  background: rgba(87, 180, 229, 0.15);
}

.nav-cta {
  background: var(--blue);
  color: var(--white) !important;
  padding: 8px 18px !important;
}
.nav-cta:hover {
  background: var(--blue-dark) !important;
}

.nav-mobile-toggle {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: 8px;
  color: var(--white);
}

.nav-mobile-toggle span {
  display: block;
  width: 24px;
  height: 2px;
  background: currentColor;
  margin: 5px 0;
  transition: all var(--transition);
}

/* ── HERO ─────────────────────────────────── */
.hero {
  background: linear-gradient(135deg, var(--navy-dark) 0%, var(--navy) 60%, #1a3a6e 100%);
  color: var(--white);
  padding: 100px 24px 80px;
  position: relative;
  overflow: hidden;
}

.hero::before {
  content: '';
  position: absolute;
  inset: 0;
  background: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='60' height='60' viewBox='0 0 60 60'%3E%3Ccircle cx='30' cy='30' r='1' fill='%2357B4E5' opacity='0.15'/%3E%3C/svg%3E") repeat;
  pointer-events: none;
}

.hero-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 48px;
  align-items: center;
  position: relative;
}

.hero-eyebrow {
  color: var(--blue);
  font-size: 0.85rem;
  font-weight: 700;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  margin-bottom: 16px;
}

.hero h1 {
  font-size: clamp(2.2rem, 5vw, 3.6rem);
  font-weight: 800;
  line-height: 1.1;
  margin-bottom: 20px;
  letter-spacing: -0.02em;
}

.hero h1 span { color: var(--blue); }

.hero-sub {
  font-size: 1.15rem;
  color: var(--blue-light);
  margin-bottom: 12px;
}

.hero-details {
  display: flex;
  flex-wrap: wrap;
  gap: 20px;
  margin-bottom: 36px;
}

.hero-detail {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 1rem;
  color: var(--gray-200);
}

.hero-detail svg { color: var(--blue); flex-shrink: 0; }

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

.hero-logo {
  width: 220px;
  flex-shrink: 0;
}

/* ── SECTION COMMON ───────────────────────── */
.section {
  padding: 80px 24px;
}

.section-alt { background: var(--off-white); }

.section-header {
  text-align: center;
  margin-bottom: 52px;
}

.section-label {
  color: var(--blue);
  font-size: 0.8rem;
  font-weight: 700;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  margin-bottom: 10px;
}

.section-title {
  font-size: clamp(1.6rem, 3vw, 2.4rem);
  font-weight: 800;
  color: var(--navy);
  letter-spacing: -0.02em;
  margin-bottom: 12px;
}

.section-desc {
  font-size: 1.05rem;
  color: var(--text-light);
  max-width: 560px;
  margin: 0 auto;
}

.section-footer {
  text-align: center;
  margin-top: 44px;
}

/* ── ABOUT ────────────────────────────────── */
.about-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 60px;
  align-items: center;
  max-width: var(--max-width);
  margin: 0 auto;
}

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

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

.about-stats {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 20px;
}

.stat-card {
  background: var(--navy);
  color: var(--white);
  padding: 28px 24px;
  border-radius: var(--radius-lg);
  text-align: center;
}

.stat-number {
  font-size: 2.4rem;
  font-weight: 800;
  color: var(--blue);
  line-height: 1;
  margin-bottom: 6px;
}

.stat-label {
  font-size: 0.85rem;
  color: var(--blue-light);
  font-weight: 500;
}

/* ── SPEAKER CARDS ────────────────────────── */
.cards-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 24px;
  max-width: var(--max-width);
  margin: 0 auto;
}

.speaker-card {
  background: var(--white);
  border: 1px solid var(--gray-200);
  border-radius: var(--radius-lg);
  overflow: hidden;
  transition: all var(--transition);
  box-shadow: var(--shadow);
}

.speaker-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
  border-color: var(--blue);
}

.speaker-photo {
  width: 100%;
  aspect-ratio: 4/3;
  object-fit: cover;
  background: var(--gray-100);
}

.speaker-photo-placeholder {
  width: 100%;
  aspect-ratio: 4/3;
  background: linear-gradient(135deg, var(--navy) 0%, var(--navy-light) 100%);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--blue-light);
  font-size: 2.5rem;
  font-weight: 700;
}

.speaker-body {
  padding: 20px;
}

.speaker-name {
  font-size: 1.05rem;
  font-weight: 700;
  color: var(--navy);
  margin-bottom: 4px;
}

.speaker-company {
  font-size: 0.85rem;
  color: var(--text-light);
  margin-bottom: 10px;
}

.speaker-talk {
  font-size: 0.9rem;
  color: var(--text);
  font-style: italic;
  border-top: 1px solid var(--gray-100);
  padding-top: 10px;
}

/* ── SCHEDULE ─────────────────────────────── */
.schedule-table {
  max-width: var(--max-width);
  margin: 0 auto;
}

.schedule-day-header {
  background: var(--navy);
  color: var(--white);
  padding: 14px 24px;
  border-radius: var(--radius);
  font-weight: 700;
  font-size: 1rem;
  margin-bottom: 8px;
  margin-top: 32px;
}

.schedule-day-header:first-child { margin-top: 0; }

.schedule-row {
  display: grid;
  grid-template-columns: 120px 1fr;
  gap: 0;
  border: 1px solid var(--gray-200);
  border-radius: var(--radius);
  margin-bottom: 8px;
  overflow: hidden;
  background: var(--white);
  transition: box-shadow var(--transition);
}

.schedule-row:hover { box-shadow: var(--shadow); }

.schedule-row.break {
  background: var(--gray-100);
  border-color: var(--gray-100);
}

.schedule-time {
  padding: 16px;
  background: var(--off-white);
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--navy);
  display: flex;
  align-items: center;
  border-right: 1px solid var(--gray-200);
}

.schedule-row.break .schedule-time { background: var(--gray-100); }

.schedule-content {
  padding: 16px 20px;
  display: flex;
  flex-direction: column;
  justify-content: center;
}

.schedule-title {
  font-weight: 600;
  color: var(--navy);
  margin-bottom: 4px;
}

.schedule-speaker {
  font-size: 0.85rem;
  color: var(--text-light);
}

.schedule-tag {
  display: inline-block;
  font-size: 0.72rem;
  font-weight: 700;
  padding: 2px 8px;
  border-radius: 20px;
  margin-bottom: 6px;
  text-transform: uppercase;
  letter-spacing: 0.06em;
}

.tag-keynote { background: #FFF3E0; color: #E65100; }
.tag-talk    { background: #E3F2FD; color: #1565C0; }
.tag-workshop{ background: #E8F5E9; color: #2E7D32; }
.tag-break   { background: var(--gray-100); color: var(--gray-600); }
.tag-social  { background: #F3E5F5; color: #6A1B9A; }

/* ── SPONSORS ─────────────────────────────── */
.sponsor-tier {
  max-width: var(--max-width);
  margin: 0 auto 48px;
}

.sponsor-tier:last-child { margin-bottom: 0; }

.tier-label {
  text-align: center;
  margin-bottom: 24px;
}

.tier-badge {
  display: inline-block;
  padding: 6px 20px;
  border-radius: 20px;
  font-size: 0.8rem;
  font-weight: 700;
  letter-spacing: 0.1em;
  text-transform: uppercase;
}

.tier-platinum { background: #E8EEF8; color: #1C3260; border: 2px solid #B0C0DC; }
.tier-gold     { background: #FFF8E1; color: #B8860B; border: 2px solid #FFD700; }
.tier-silver   { background: #F5F5F5; color: #666; border: 2px solid #C0C0C0; }
.tier-bronze   { background: #FBF0E8; color: #8B4513; border: 2px solid #CD7F32; }
.tier-community{ background: #E8F5E9; color: #2E7D32; border: 2px solid #81C784; }
.tier-recruiting{ background: #EDE7F6; color: #4527A0; border: 2px solid #9575CD; }

.sponsor-logos {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  align-items: center;
  gap: 24px;
}

.sponsor-logo-card {
  background: var(--white);
  border: 1px solid var(--gray-200);
  border-radius: var(--radius);
  padding: 20px 32px;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all var(--transition);
  box-shadow: var(--shadow);
}

.sponsor-logo-card:hover {
  border-color: var(--blue);
  box-shadow: var(--shadow-lg);
  transform: translateY(-2px);
}

.sponsor-logo-card img { height: 48px; width: auto; object-fit: contain; }

.tier-platinum .sponsor-logo-card img { height: 72px; }
.tier-gold .sponsor-logo-card img { height: 56px; }

/* ── PHOTOS GALLERY ───────────────────────── */
.photo-gallery {
  max-width: var(--max-width);
  margin: 0 auto;
  columns: 3;
  column-gap: 16px;
}

.photo-item {
  break-inside: avoid;
  margin-bottom: 16px;
  border-radius: var(--radius);
  overflow: hidden;
  cursor: pointer;
}

.photo-item img {
  width: 100%;
  transition: transform 0.3s ease;
}

.photo-item:hover img { transform: scale(1.03); }

.photo-lightbox {
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.92);
  z-index: 1000;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 24px;
}

.photo-lightbox img {
  max-width: 90vw;
  max-height: 85vh;
  object-fit: contain;
  border-radius: var(--radius);
}

.lightbox-close {
  position: absolute;
  top: 20px;
  right: 24px;
  background: none;
  border: none;
  color: var(--white);
  font-size: 2rem;
  cursor: pointer;
  line-height: 1;
}

/* ── VOLUNTEERS ───────────────────────────── */
.volunteer-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(180px, 1fr));
  gap: 20px;
  max-width: var(--max-width);
  margin: 0 auto;
}

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

.volunteer-avatar {
  width: 80px;
  height: 80px;
  border-radius: 50%;
  object-fit: cover;
  margin: 0 auto 10px;
  border: 3px solid var(--blue);
  background: var(--gray-100);
}

.volunteer-avatar-placeholder {
  width: 80px;
  height: 80px;
  border-radius: 50%;
  background: var(--navy);
  color: var(--blue-light);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 1.3rem;
  margin: 0 auto 10px;
  border: 3px solid var(--blue);
}

.volunteer-name {
  font-weight: 600;
  font-size: 0.9rem;
  color: var(--navy);
}

.volunteer-role {
  font-size: 0.8rem;
  color: var(--text-light);
}

/* ── FORM ─────────────────────────────────── */
.form-section {
  background: var(--navy);
  color: var(--white);
}

.form-section .section-title { color: var(--white); }
.form-section .section-desc  { color: var(--blue-light); }

.interest-form {
  max-width: 560px;
  margin: 0 auto;
  background: rgba(255,255,255,0.06);
  padding: 36px;
  border-radius: var(--radius-lg);
  border: 1px solid rgba(87,180,229,0.2);
}

.form-group {
  margin-bottom: 20px;
}

.form-group label {
  display: block;
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--blue-light);
  margin-bottom: 6px;
}

.form-group input,
.form-group select {
  width: 100%;
  padding: 11px 14px;
  border: 1.5px solid rgba(87,180,229,0.3);
  border-radius: var(--radius);
  background: rgba(255,255,255,0.08);
  color: var(--white);
  font-size: 0.95rem;
  transition: border-color var(--transition);
  font-family: inherit;
}

.form-group input::placeholder { color: rgba(255,255,255,0.3); }

.form-group input:focus,
.form-group select:focus {
  outline: none;
  border-color: var(--blue);
  background: rgba(255,255,255,0.12);
}

.form-group select option { background: var(--navy); color: var(--white); }

.form-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
}

.form-submit {
  width: 100%;
  padding: 14px;
  font-size: 1rem;
  margin-top: 8px;
}

.form-message {
  text-align: center;
  margin-top: 14px;
  font-size: 0.9rem;
  min-height: 24px;
}

.form-message.success { color: #4CAF50; }
.form-message.error   { color: #FF5252; }

/* ── FOOTER ───────────────────────────────── */
.site-footer {
  background: var(--navy-dark);
  color: var(--gray-400);
  padding: 52px 24px 28px;
}

.footer-inner {
  max-width: var(--max-width);
  margin: 0 auto;
}

.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: 40px;
  margin-bottom: 40px;
}

.footer-brand img { height: 48px; margin-bottom: 16px; }

.footer-brand p {
  font-size: 0.88rem;
  line-height: 1.7;
  max-width: 260px;
}

.footer-col h4 {
  color: var(--white);
  font-size: 0.85rem;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  margin-bottom: 14px;
}

.footer-col ul { list-style: none; }

.footer-col li { margin-bottom: 8px; }

.footer-col a {
  color: var(--gray-400);
  font-size: 0.88rem;
  transition: color var(--transition);
}

.footer-col a:hover { color: var(--blue); }

.footer-bottom {
  border-top: 1px solid rgba(255,255,255,0.08);
  padding-top: 24px;
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 0.82rem;
  flex-wrap: wrap;
  gap: 12px;
}

.footer-bottom a { color: var(--gray-400); }
.footer-bottom a:hover { color: var(--blue); }

/* ── LOADING / EMPTY STATES ───────────────── */
.loading-state, .empty-state {
  text-align: center;
  padding: 60px 24px;
  color: var(--text-light);
}

.spinner {
  width: 40px;
  height: 40px;
  border: 3px solid var(--gray-200);
  border-top-color: var(--blue);
  border-radius: 50%;
  animation: spin 0.7s linear infinite;
  margin: 0 auto 16px;
}

@keyframes spin { to { transform: rotate(360deg); } }

/* ── PAGE HERO (inner pages) ──────────────── */
.page-hero {
  background: linear-gradient(135deg, var(--navy-dark) 0%, var(--navy) 100%);
  color: var(--white);
  padding: 64px 24px;
  text-align: center;
}

.page-hero h1 {
  font-size: clamp(1.8rem, 4vw, 2.8rem);
  font-weight: 800;
  letter-spacing: -0.02em;
  margin-bottom: 10px;
}

.page-hero p {
  color: var(--blue-light);
  font-size: 1.05rem;
}

/* ── RESPONSIVE ───────────────────────────── */
@media (max-width: 900px) {
  .hero-inner { grid-template-columns: 1fr; }
  .hero-logo { display: none; }
  .about-grid { grid-template-columns: 1fr; gap: 40px; }
  .footer-grid { grid-template-columns: 1fr 1fr; }
  .photo-gallery { columns: 2; }
}

@media (max-width: 680px) {
  .section { padding: 56px 24px; }
  .nav-links { display: none; }
  .nav-links.open {
    display: flex;
    flex-direction: column;
    position: absolute;
    top: 68px;
    left: 0;
    right: 0;
    background: var(--navy-dark);
    padding: 16px;
    border-bottom: 3px solid var(--blue);
    gap: 4px;
  }
  .nav-mobile-toggle { display: block; }
  .site-nav { position: relative; }
  .footer-grid { grid-template-columns: 1fr; }
  .photo-gallery { columns: 1; }
  .about-stats { grid-template-columns: 1fr 1fr; }
  .form-row { grid-template-columns: 1fr; }
  .schedule-row { grid-template-columns: 90px 1fr; }
}