:root {
  --blue-900: #042C53;
  --blue-800: #0C447C;
  --blue-700: #1F4E79;
  --blue-600: #185FA5;
  --blue-400: #378ADD;
  --blue-200: #85B7EB;
  --blue-100: #B5D4F4;
  --blue-50: #E6F1FB;

  --amber-800: #633806;
  --amber-50: #FAEEDA;

  --ink: #1A1D21;
  --ink-soft: #4A5159;
  --ink-faint: #7A828B;
  --paper: #FFFFFF;
  --paper-alt: #F5F7FA;
  --border: #DDE3EA;

  --radius-md: 8px;
  --radius-lg: 12px;
  --max-width: 880px;

  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: var(--font-sans);
  color: var(--ink);
  background: var(--paper);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

a { color: var(--blue-600); text-decoration: none; }
a:hover { text-decoration: underline; }

h1, h2, h3 { font-weight: 600; line-height: 1.25; margin: 0; }

/* ---------- Nav ---------- */
.nav {
  background: var(--blue-700);
  position: sticky;
  top: 0;
  z-index: 50;
}
.nav-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 1.5rem;
  height: 56px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}
.nav-brand {
  color: #fff;
  font-weight: 600;
  font-size: 1.05rem;
  letter-spacing: 0.02em;
}
.nav-brand:hover { text-decoration: none; opacity: 0.9; }
.nav-links { display: flex; gap: 1.75rem; }
.nav-links a {
  color: rgba(255,255,255,0.78);
  font-size: 0.875rem;
  font-weight: 500;
}
.nav-links a:hover { color: #fff; text-decoration: none; }
.nav-toggle { display: none; }

/* ---------- Hero ---------- */
.hero {
  background: linear-gradient(180deg, var(--blue-700), var(--blue-800));
  color: #fff;
  padding: 4rem 1.5rem 3.5rem;
}
.hero-inner { max-width: var(--max-width); margin: 0 auto; }
.hero-badge {
  display: inline-block;
  background: rgba(255,255,255,0.14);
  border: 1px solid rgba(255,255,255,0.25);
  color: rgba(255,255,255,0.92);
  font-size: 0.8rem;
  font-weight: 500;
  padding: 0.3rem 0.85rem;
  border-radius: 999px;
  margin-bottom: 1.25rem;
}
.hero h1 {
  font-size: clamp(1.6rem, 4vw, 2.4rem);
  margin-bottom: 0.9rem;
}
.hero h1 .accent { color: var(--blue-200); }
.hero-sub {
  font-size: 1.05rem;
  color: rgba(255,255,255,0.78);
  max-width: 640px;
  margin: 0 0 1.75rem;
}
.hero-meta {
  list-style: none;
  display: flex;
  flex-wrap: wrap;
  gap: 1.5rem 2rem;
  padding: 0;
  margin: 0 0 2rem;
}
.hero-meta li {
  font-size: 0.9rem;
  color: rgba(255,255,255,0.85);
}
.hero-meta strong {
  display: block;
  font-size: 0.72rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--blue-200);
  font-weight: 600;
  margin-bottom: 0.2rem;
}
.hero-cta { display: flex; gap: 0.85rem; flex-wrap: wrap; }

.btn {
  display: inline-block;
  padding: 0.65rem 1.3rem;
  border-radius: var(--radius-md);
  font-size: 0.9rem;
  font-weight: 600;
  text-decoration: none;
  transition: opacity 0.15s ease;
}
.btn:hover { text-decoration: none; opacity: 0.88; }
.btn-primary { background: #fff; color: var(--blue-700); }
.btn-secondary { background: rgba(255,255,255,0.12); color: #fff; border: 1px solid rgba(255,255,255,0.35); }
.btn-disabled { opacity: 0.55; pointer-events: none; }

/* ---------- Sections ---------- */
main { max-width: var(--max-width); margin: 0 auto; }
.section { padding: 3.25rem 1.5rem; border-bottom: 1px solid var(--border); }
.section.alt { background: var(--paper-alt); }
.section-title {
  font-size: 0.78rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--blue-700);
  margin-bottom: 1.5rem;
}
.section-intro { color: var(--ink-soft); margin: 0 0 1.5rem; font-size: 1rem; }
.section-body p { color: var(--ink-soft); margin: 0 0 1rem; font-size: 0.98rem; }
.section-body p:last-child { margin-bottom: 0; }

.keywords { display: flex; flex-wrap: wrap; gap: 0.5rem; margin-top: 1.5rem; }
.kw {
  background: var(--blue-50);
  color: var(--blue-800);
  border-radius: 999px;
  padding: 0.3rem 0.8rem;
  font-size: 0.8rem;
  font-weight: 500;
}

/* ---------- Topics ---------- */
.topics-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 1rem;
}
.topic-card {
  background: var(--paper);
  border: 1px solid var(--border);
  border-left: 3px solid var(--blue-700);
  border-radius: var(--radius-md);
  padding: 1.1rem 1.25rem;
}
.topic-card h3 { font-size: 0.98rem; margin-bottom: 0.6rem; color: var(--ink); }
.topic-card ul { margin: 0; padding-left: 1.1rem; }
.topic-card li { font-size: 0.85rem; color: var(--ink-soft); margin-bottom: 0.35rem; }
.topic-card li:last-child { margin-bottom: 0; }

/* ---------- Dates ---------- */
.dates-table { display: flex; flex-direction: column; }
.date-row {
  display: flex;
  align-items: center;
  gap: 1rem;
  padding: 0.85rem 0;
  border-bottom: 1px solid var(--border);
}
.date-row:last-child { border-bottom: none; }
.date-row.highlight { background: var(--blue-50); margin: 0 -1rem; padding: 0.85rem 1rem; border-radius: var(--radius-md); border-bottom: none; }
.date-when { font-weight: 600; font-size: 0.92rem; color: var(--blue-700); min-width: 150px; }
.date-what { font-size: 0.92rem; color: var(--ink-soft); flex: 1; }
.date-tag {
  font-size: 0.72rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.03em;
  color: var(--ink-faint);
  white-space: nowrap;
}
.date-tag.tag-primary { background: var(--blue-700); color: #fff; padding: 0.2rem 0.6rem; border-radius: 999px; }
.date-tag.tag-warn { background: var(--amber-50); color: var(--amber-800); padding: 0.2rem 0.6rem; border-radius: 999px; }
.dates-note { font-size: 0.85rem; color: var(--ink-faint); margin-top: 1.25rem; }

/* ---------- Submission ---------- */
.formats-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 1rem;
  margin: 1.25rem 0 1.5rem;
}
.format-card {
  background: var(--paper);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 1.1rem 1.25rem;
  display: flex;
  flex-direction: column;
  gap: 0.2rem;
}
.format-label { font-weight: 600; font-size: 0.92rem; }
.format-pages { font-size: 1.3rem; font-weight: 700; color: var(--blue-700); }
.format-extra { font-size: 0.8rem; color: var(--ink-faint); }

.submit-cta {
  background: var(--blue-50);
  border-radius: var(--radius-lg);
  padding: 1.1rem 1.4rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  margin: 1.25rem 0;
  flex-wrap: wrap;
}
.submit-cta-title { font-weight: 600; color: var(--blue-800); margin: 0; font-size: 0.95rem; }
.submit-cta-sub { color: var(--blue-600); margin: 0.1rem 0 0; font-size: 0.82rem; }

/* ---------- Program Committee ---------- */
.pc-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 0.5rem 1.5rem;
}
.pc-item {
  padding: 0.7rem 0;
  border-bottom: 1px solid var(--border);
  display: flex;
  flex-direction: column;
}
.pc-name { font-weight: 600; font-size: 0.92rem; color: var(--ink); }
.pc-aff { font-size: 0.8rem; color: var(--ink-faint); margin-top: 0.15rem; }

/* ---------- Organizers ---------- */
.org-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 1.25rem;
}
.org-card {
  background: var(--paper);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 1.4rem;
}
.org-initials {
  width: 42px; height: 42px;
  border-radius: 50%;
  background: var(--blue-50);
  color: var(--blue-700);
  display: flex; align-items: center; justify-content: center;
  font-weight: 700; font-size: 0.85rem;
  margin-bottom: 0.85rem;
}
.org-name { font-weight: 600; font-size: 1rem; margin: 0 0 0.35rem; }
.org-role { font-size: 0.85rem; color: var(--ink-soft); margin: 0 0 0.65rem; line-height: 1.5; }
.org-contact { font-size: 0.85rem; margin: 0.15rem 0; }

/* ---------- Footer ---------- */
.footer {
  text-align: center;
  padding: 2rem 1.5rem;
  color: var(--ink-faint);
  font-size: 0.82rem;
}

/* ---------- Responsive ---------- */
@media (max-width: 640px) {
  .nav-links { display: none; }
  .nav-toggle {
    display: flex;
    flex-direction: column;
    gap: 4px;
    background: none;
    border: none;
    padding: 0.5rem;
    cursor: pointer;
  }
  .nav-toggle span { width: 20px; height: 2px; background: #fff; display: block; }
  .nav.open .nav-links {
    display: flex;
    flex-direction: column;
    position: absolute;
    top: 56px;
    left: 0;
    right: 0;
    background: var(--blue-700);
    padding: 1rem 1.5rem 1.5rem;
    gap: 0.9rem;
  }
  .date-row { flex-wrap: wrap; }
  .date-when { min-width: 100%; }
}

/* ---------- Reduced motion ---------- */
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .btn { transition: none; }
}

/* ---------- Focus visibility ---------- */
a:focus-visible, button:focus-visible {
  outline: 2px solid var(--blue-400);
  outline-offset: 2px;
}