:root {
  --accent: #0f6f6b;
  --accent-soft: #12857f;
  --accent-dark: #0b4f4c;
  --ink: #1c2427;
  --ink-soft: #4a5559;
  --bg: #ffffff;
  --bg-alt: #f4f7f7;
  --card-bg: #ffffff;
  --border: #e1e8e8;
  --footer-bg: #1c2427;
  --footer-ink: #cfd8d8;
  --footer-ink-soft: #9fb0b0;
  --footer-link: #7fd6cf;
  --solid: #0f6f6b;
  --solid-hover: #0b4f4c;
  --logo-chip-bg: #ffffff;
  --radius: 10px;
  --max-width: 960px;
}

@media (prefers-color-scheme: dark) {
  :root {
    --accent: #3fb6ac;
    --accent-soft: #57c9bf;
    --accent-dark: #7fe0d6;
    --ink: #eaf1f0;
    --ink-soft: #a9bcbb;
    --bg: #101516;
    --bg-alt: #171f20;
    --card-bg: #1a2223;
    --border: #2a3435;
    --footer-bg: #0a0e0f;
    --footer-ink: #c3d1d0;
    --footer-ink-soft: #6f8382;
    --footer-link: #6fd6cc;
  }
}

:root[data-theme="dark"] {
  --accent: #3fb6ac;
  --accent-soft: #57c9bf;
  --accent-dark: #7fe0d6;
  --ink: #eaf1f0;
  --ink-soft: #a9bcbb;
  --bg: #101516;
  --bg-alt: #171f20;
  --card-bg: #1a2223;
  --border: #2a3435;
  --footer-bg: #0a0e0f;
  --footer-ink: #c3d1d0;
  --footer-ink-soft: #6f8382;
  --footer-link: #6fd6cc;
}

:root[data-theme="light"] {
  --accent: #0f6f6b;
  --accent-soft: #12857f;
  --accent-dark: #0b4f4c;
  --ink: #1c2427;
  --ink-soft: #4a5559;
  --bg: #ffffff;
  --bg-alt: #f4f7f7;
  --card-bg: #ffffff;
  --border: #e1e8e8;
  --footer-bg: #1c2427;
  --footer-ink: #cfd8d8;
  --footer-ink-soft: #9fb0b0;
  --footer-link: #7fd6cf;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  color: var(--ink);
  background: var(--bg);
  line-height: 1.6;
}

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

/* Header / nav */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: color-mix(in srgb, var(--bg) 92%, transparent);
  backdrop-filter: blur(6px);
  border-bottom: 1px solid var(--border);
}

.nav {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0.85rem 1.5rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.nav-brand {
  font-weight: 700;
  font-size: 1.15rem;
  color: var(--accent-dark);
  text-decoration: none;
  letter-spacing: 0.02em;
}

.nav-links {
  list-style: none;
  display: flex;
  gap: 1.75rem;
  margin: 0;
  padding: 0;
}

.nav-links a {
  color: var(--ink-soft);
  text-decoration: none;
  font-size: 0.95rem;
  font-weight: 500;
  transition: color 0.15s ease;
}

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

.nav-toggle {
  display: none;
  flex-direction: column;
  justify-content: space-between;
  width: 24px;
  height: 18px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 0;
}

.nav-toggle span {
  display: block;
  height: 2px;
  width: 100%;
  background: var(--ink);
  border-radius: 1px;
}

/* Hero */
.hero {
  background: linear-gradient(180deg, var(--bg-alt) 0%, var(--bg) 100%);
  padding: 5rem 1.5rem 4rem;
  text-align: center;
}

.hero-inner { max-width: 760px; margin: 0 auto; }

.neurips-badge {
  display: inline-flex;
  align-items: center;
  background: var(--logo-chip-bg);
  padding: 0.9rem 1.6rem;
  border-radius: 10px;
  margin-bottom: 1.5rem;
  opacity: 0.92;
  transition: opacity 0.15s ease;
}

.neurips-badge:hover { opacity: 1; }

.neurips-badge img {
  display: block;
  height: 50px;
  width: auto;
}

.eyebrow {
  color: var(--accent);
  font-weight: 600;
  letter-spacing: 0.05em;
  text-transform: uppercase;
  font-size: 0.85rem;
  margin-bottom: 1rem;
}

.hero h1 {
  font-size: clamp(1.8rem, 4vw, 2.6rem);
  line-height: 1.25;
  margin: 0 0 1.1rem;
  color: var(--ink);
}

.tagline {
  font-size: 1.1rem;
  color: var(--ink-soft);
  margin: 0 0 0.75rem;
}

.hero-meta {
  font-size: 0.95rem;
  color: var(--ink-soft);
  margin: 0 0 2rem;
}

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

.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.7rem 1.4rem;
  border-radius: 999px;
  font-weight: 600;
  font-size: 0.95rem;
  text-decoration: none;
  transition: transform 0.15s ease, box-shadow 0.15s ease;
}

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

.btn-primary:hover { background: var(--solid-hover); }

.btn-secondary {
  background: transparent;
  color: var(--accent-dark);
  border: 1.5px solid var(--accent);
}

.btn-secondary:hover { background: var(--bg-alt); }

.btn-standalone { margin-top: 1.25rem; }

/* Sections */
.section { padding: 4rem 0; }
.section-alt { background: var(--bg-alt); }

.section h2 {
  font-size: 1.7rem;
  margin: 0 0 1.5rem;
  color: var(--ink);
}

.section h3 {
  font-size: 1.15rem;
  margin: 2rem 0 1rem;
  color: var(--accent-dark);
}

.section p { color: var(--ink-soft); }

.topics-list {
  padding-left: 1.2rem;
  margin: 0;
}

.topics-list li {
  margin-bottom: 1rem;
  color: var(--ink-soft);
}

.topics-list strong { color: var(--ink); }

.fineprint {
  font-size: 0.85rem;
  color: var(--ink-soft);
  opacity: 0.85;
}

/* Tables */
.table-wrap { overflow-x: auto; }

table {
  width: 100%;
  border-collapse: collapse;
  margin: 1rem 0;
  font-size: 0.95rem;
}

.dates-table td, .schedule-table td, .schedule-table th {
  padding: 0.65rem 0.9rem;
  border-bottom: 1px solid var(--border);
  text-align: left;
}

.schedule-table th {
  background: var(--bg-alt);
  font-weight: 600;
  color: var(--ink);
}

.dates-table td:first-child { color: var(--ink); font-weight: 500; }
.dates-table td:last-child { color: var(--ink-soft); }

.schedule-table td:first-child {
  white-space: nowrap;
  color: var(--accent-dark);
  font-weight: 600;
  width: 130px;
}

/* People grids */
.people-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 1.5rem;
}

.person-card {
  background: var(--card-bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.5rem;
}

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

.avatar {
  width: 96px;
  height: 96px;
  border-radius: 50%;
  background: var(--solid);
  color: #fff;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 1.5rem;
  margin-bottom: 1rem;
}

.avatar-photo {
  display: block;
  width: 96px;
  height: 96px;
  border-radius: 50%;
  object-fit: cover;
  object-position: center;
  margin-bottom: 1rem;
}

.avatar-photo--top {
  object-position: 50% 15%;
}

.person-card h3 {
  margin: 0 0 0.25rem;
  font-size: 1.05rem;
  color: var(--ink);
}

.person-card h3 a {
  color: inherit;
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: border-color 0.15s ease, color 0.15s ease;
}

.person-card h3 a:hover {
  color: var(--accent-dark);
  border-bottom-color: var(--accent);
}

.affiliation {
  font-size: 0.85rem;
  color: var(--accent-dark);
  font-weight: 500;
  margin: 0 0 0.6rem;
}

.bio {
  font-size: 0.9rem;
  margin: 0;
}

/* Sponsors */
.sponsor-grid {
  display: flex;
  gap: 1.25rem;
  flex-wrap: wrap;
  margin: 1.5rem 0;
}

.sponsor-card {
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--logo-chip-bg);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.25rem 2rem;
}

.sponsor-logo {
  display: block;
  height: 52px;
  width: auto;
  max-width: 260px;
  object-fit: contain;
}

/* Footer */
.site-footer {
  background: var(--footer-bg);
  color: var(--footer-ink);
  padding: 2.5rem 0;
  text-align: center;
}

.site-footer p { margin: 0.3rem 0; }
.site-footer a { color: var(--footer-link); }
.site-footer .fineprint { color: var(--footer-ink-soft); }

/* Mobile */
@media (max-width: 720px) {
  .nav-toggle { display: flex; }

  .nav-links {
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background: var(--bg);
    border-bottom: 1px solid var(--border);
    flex-direction: column;
    gap: 0;
    padding: 0.5rem 1.5rem;
    display: none;
  }

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

  .nav-links li { border-top: 1px solid var(--border); }
  .nav-links li:first-child { border-top: none; }
  .nav-links a { display: block; padding: 0.85rem 0; }
}