/* ==========================================================================
   PTA @ NeurIPS 2026 — shared stylesheet
   Design language carried over from the original Google Sites embeds
   (banner.html + schedule.html) so the new site keeps the same look & feel.
   ========================================================================== */

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

/* ==========================================================================
   Global layout tokens — change --page-width here to resize every page
   at once. --text-measure controls the max line-length of body paragraphs
   (kept narrower than the full page width for readability).
   ========================================================================== */
:root {
  --page-width: 1080px;
  --text-measure: 760px;
  --hero-title-width: 900px;
  --hero-subtitle-width: 640px;

  /* Dark gradient laid on top of banner.png so white text stays readable.
     Lower the alpha values (0 = fully transparent, 1 = fully opaque) to
     let more of the original image color show through. */
  --banner-overlay: linear-gradient(
    160deg,
    rgba(15, 23, 42, 0.55) 0%,
    rgba(30, 41, 59, 0.42) 55%,
    rgba(12, 35, 64, 0.58) 100%
  );
  --banner-image: url('/assets/images/banner.png');
}

html {
  scroll-behavior: smooth;
}

body {
  font-family: 'Inter', system-ui, -apple-system, sans-serif;
  background: #f8fafc;
  color: #1e293b;
  -webkit-font-smoothing: antialiased;
  min-height: 100%;
  display: flex;
  flex-direction: column;
}

main {
  flex: 1 0 auto;
}

img { max-width: 100%; display: block; }
a { color: inherit; text-decoration: none; }

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

/* ── Site header / nav ── */
.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  background: #0f172a;
  border-bottom: 1px solid rgba(255,255,255,0.08);
}
.nav {
  width: 100%;
  margin: 0;
  padding: 14px 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  flex-wrap: wrap;
}
.nav-brand {
  display: flex;
  align-items: center;
  gap: 10px;
}
.nav-logo {
  height: 28px;
  width: auto;
  border-radius: 6px;
}
.nav-brand-text {
  font-weight: 800;
  font-size: 17px;
  color: #f1f5f9;
  letter-spacing: -0.01em;
}
.nav-brand .brand-accent {
  color: #60a5fa;
  font-style: italic;
}
.nav-links {
  display: flex;
  flex-wrap: wrap;
  gap: 4px;
}
.nav-links a {
  font-size: 14px;
  font-weight: 600;
  color: #cbd5e1;
  padding: 8px 12px;
  border-radius: 8px;
  transition: background 0.15s, color 0.15s;
}
.nav-links a:hover {
  background: rgba(255,255,255,0.08);
  color: #f1f5f9;
}
.nav-links a.active {
  color: #fbbf24;
  background: rgba(245,158,11,0.12);
}

/* ── Hero (home page) ── */
.hero {
  position: relative;
  width: 100%;
  overflow: hidden;
  background: var(--banner-overlay), var(--banner-image);
  background-size: cover;
  background-position: center;
  background-repeat: no-repeat;
  padding: 72px 24px 76px;
  text-align: center;
}
.badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  background: rgba(245,158,11,0.15);
  border: 1px solid rgba(245,158,11,0.4);
  color: #fbbf24;
  font-size: 12px;
  font-weight: 600;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  padding: 5px 14px;
  border-radius: 999px;
  margin-bottom: 24px;
}
.badge-dot {
  width: 6px; height: 6px;
  background: #f59e0b;
  border-radius: 50%;
  animation: pulse 2s ease-in-out infinite;
}
@keyframes pulse {
  0%,100% { opacity: 1; transform: scale(1); }
  50%      { opacity: 0.4; transform: scale(1.4); }
}
/* ── Global h1 (used by the home hero AND every page-banner, so every
   page title is the same size/weight/color) ── */
h1 {
  font-size: clamp(28px, 4.5vw, 46px);
  font-weight: 800;
  line-height: 1.2;
  letter-spacing: -0.02em;
  color: #f1f5f9;
  text-shadow: 0 2px 16px rgba(0, 0, 0, 0.45);
  margin-bottom: 10px;
}

.title {
  position: relative;
  margin: 0 auto 20px;
  max-width: var(--hero-title-width);
}
.title .brand-accent {
  color: #60a5fa;
  font-style: italic;
}
.title .highlight {
  color: #fbbf24;
}
.divider {
  width: 48px; height: 3px;
  background: linear-gradient(90deg, #3b82f6, #f59e0b);
  border-radius: 99px;
  margin: 0 auto 20px;
}
.divider.left {
  margin: 0 0 24px;
}
.subtitle {
  font-size: clamp(14px, 2vw, 18px);
  font-weight: 500;
  color: #cbd5e1;
  text-shadow: 0 1px 8px rgba(0, 0, 0, 0.4);
  max-width: var(--hero-subtitle-width);
  margin: 0 auto 32px;
  line-height: 1.6;
}
.tags {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 10px;
  margin-bottom: 36px;
}
.tag {
  background: rgba(255,255,255,0.07);
  border: 1px solid rgba(255,255,255,0.12);
  color: #cbd5e1;
  font-size: 12px;
  font-weight: 500;
  padding: 6px 14px;
  border-radius: 999px;
  transition: background 0.2s;
}
.tag:hover { background: rgba(255,255,255,0.13); }

.hero-ctas {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 12px;
}
.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 11px 22px;
  border-radius: 10px;
  font-size: 14px;
  font-weight: 700;
  transition: transform 0.15s, box-shadow 0.15s, background 0.15s;
  border: 1px solid transparent;
}
.btn-primary {
  background: linear-gradient(90deg, #3b82f6, #2563eb);
  color: #f8fafc;
  box-shadow: 0 6px 18px rgba(37,99,235,0.35);
}
.btn-primary:hover { transform: translateY(-1px); box-shadow: 0 8px 22px rgba(37,99,235,0.45); }
.btn-secondary {
  background: rgba(255,255,255,0.06);
  border-color: rgba(255,255,255,0.18);
  color: #f1f5f9;
}
.btn-secondary:hover { background: rgba(255,255,255,0.12); }

/* ── Global headings (apply the same way on every page) ── */
h2 {
  font-size: clamp(22px, 3.5vw, 30px);
  font-weight: 800;
  letter-spacing: -0.02em;
  color: #0f172a;
  margin-bottom: 10px;
}
h3 {
  font-size: 18px;
  font-weight: 700;
  color: #0f172a;
}

/* ── General page sections ── */
.section {
  padding: 56px 0;
}
.section > p.lead {
  font-size: 16px;
  color: #475569;
  max-width: var(--text-measure);
  margin-bottom: 8px;
}
.section-body p {
  font-size: 16px;
  line-height: 1.75;
  color: #334155;
  margin-bottom: 16px;
  max-width: 100%;
}
.section:nth-of-type(even) { background: #ffffff; }

/* ── Page banner (every non-home page shows the same banner image, with a
   big bold centered title) ── */
.page-banner {
  position: relative;
  width: 100%;
  min-height: 260px;
  overflow: hidden;
  background: var(--banner-overlay), var(--banner-image);
  background-size: cover;
  background-position: center;
  background-repeat: no-repeat;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: 56px 24px;
}
.page-banner h1 {
  font-size: clamp(40px, 7vw, 72px);
  margin-bottom: 12px;
  background: linear-gradient(90deg, #60a5fa 0%, #f1f5f9 50%, #fbbf24 100%);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}
.page-banner-sub {
  font-size: 17px;
  color: #cbd5e1;
  text-shadow: 0 1px 8px rgba(0, 0, 0, 0.4);
  line-height: 1.6;
  max-width: var(--hero-subtitle-width);
  margin: 0 auto;
}

/* ── Page content (everything below the banner) ── */
.page-content {
  padding: 48px 0 0;
}

/* ── Key dates ── */
.dates-list {
  list-style: none;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(230px, 1fr));
  gap: 14px;
  margin-top: 24px;
}
.dates-list li {
  background: #ffffff;
  border: 1px solid #e2e8f0;
  border-left: 4px solid #3b82f6;
  border-radius: 10px;
  padding: 16px 18px;
}
.date-label {
  display: block;
  font-size: 13px;
  font-weight: 600;
  color: #64748b;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  margin-bottom: 6px;
}
.date-value {
  display: block;
  font-size: 16px;
  font-weight: 700;
  color: #0f172a;
}

/* ── Quick link cards on home page ── */
.quick-links {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 16px;
  margin-top: 24px;
}
.quick-link-card {
  display: block;
  background: #ffffff;
  border: 1px solid #e2e8f0;
  border-radius: 12px;
  padding: 22px 20px;
  transition: transform 0.15s, box-shadow 0.15s, border-color 0.15s;
}
.quick-link-card:hover {
  transform: translateY(-2px);
  box-shadow: 0 10px 24px rgba(15,23,42,0.08);
  border-color: #cbd5e1;
}
.quick-link-card h3 {
  font-size: 16px;
  font-weight: 700;
  color: #0f172a;
  margin-bottom: 6px;
}
.quick-link-card p {
  font-size: 14px;
  color: #64748b;
}
.quick-link-card .arrow {
  color: #3b82f6;
  font-weight: 700;
}

/* ── Format list (CFP page) ── */
.format-list {
  list-style: none;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 16px;
  margin: 20px 0 32px;
}
.format-list li {
  background: #ffffff;
  border: 1px solid #e2e8f0;
  border-radius: 12px;
  padding: 18px 20px;
  font-size: 15px;
  color: #334155;
  line-height: 1.6;
}
.format-list li strong {
  display: block;
  color: #0f172a;
  font-size: 15px;
  margin-bottom: 4px;
}

.callout {
  background: rgba(59,130,246,0.08);
  border: 1px solid rgba(59,130,246,0.25);
  border-radius: 12px;
  padding: 18px 20px;
  font-size: 15px;
  color: #1e3a5f;
  line-height: 1.6;
  margin-bottom: 28px;
}
.callout a {
  color: #2563eb;
  font-weight: 700;
  text-decoration: underline;
}
.callout.todo {
  background: rgba(245,158,11,0.1);
  border-color: rgba(245,158,11,0.35);
  color: #7c4a03;
}

/* ── Schedule table ── */
.schedule-wrap {
  border: 1px solid #e2e8f0;
  border-radius: 12px;
  overflow: hidden;
  background: #ffffff;
  margin-bottom: 48px;
}
.schedule-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 16px;
}
.schedule-table th,
.schedule-table td {
  border-bottom: 1px solid #e2e8f0;
  padding: 14px 18px;
  text-align: left;
  vertical-align: middle;
  line-height: 1.5;
}
.schedule-table tbody tr:last-child td {
  border-bottom: none;
}
.schedule-table th {
  background: linear-gradient(135deg, #0f172a 0%, #1e293b 60%, #0c2340 100%);
  font-weight: 700;
  font-size: 15px;
  color: #f1f5f9;
  letter-spacing: 0.02em;
}
.schedule-table td { color: #334155; }
.col-time {
  width: 26%;
  font-variant-numeric: tabular-nums;
  font-weight: 600;
  color: #475569;
}
.schedule-table tr.talk {
  background: rgba(245,158,11,0.18);
  border-left: 4px solid #f59e0b;
}
.schedule-table tr.talk .col-time { color: #d97706; }
.schedule-table tr.talk td:last-child { color: #1e293b; font-weight: 500; }
.schedule-table tr.session {
  background: rgba(59,130,246,0.14);
  border-left: 4px solid #3b82f6;
}
.schedule-table tr.session .col-time { color: #3b82f6; }
.schedule-table tr.session td:last-child { color: #1e3a5f; font-weight: 600; }
.schedule-table tr.break {
  background: #f8fafc;
  border-left: 4px solid #cbd5e1;
}
.schedule-table tr.break .col-time { color: #64748b; font-weight: 500; }
.schedule-table tr.break td:last-child { color: #475569; }

/* ── People grid (Speakers / Organizers) ── */
.people-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(230px, 1fr));
  gap: 24px;
  margin-bottom: 48px;
}
.person-card {
  background: linear-gradient(135deg, #0f172a 0%, #1e293b 60%, #0c2340 100%);
  border: 1px solid rgba(255,255,255,0.08);
  border-radius: 14px;
  padding: 24px 18px;
  text-align: center;
  transition: transform 0.15s, box-shadow 0.15s, border-color 0.15s;
}
.person-card:hover {
  transform: translateY(-3px);
  box-shadow: 0 12px 28px rgba(0,0,0,0.35);
  border-color: rgba(96,165,250,0.4);
}
.person-photo-wrap {
  width: 104px;
  height: 104px;
  margin: 0 auto 16px;
  border-radius: 50%;
  overflow: hidden;
  background: rgba(255,255,255,0.08);
  border: 3px solid rgba(255,255,255,0.15);
}
.person-photo {
  width: 100%;
  height: 100%;
  object-fit: cover;
}
.person-name {
  font-size: 16px;
  font-weight: 700;
  color: #f1f5f9;
  margin-bottom: 4px;
}
.person-name a:hover { color: #60a5fa; }
.person-affiliation {
  font-size: 13px;
  color: #94a3b8;
  line-height: 1.5;
}
.person-link {
  display: inline-block;
  margin-top: 10px;
  font-size: 12px;
  font-weight: 700;
  color: #fbbf24;
  letter-spacing: 0.02em;
}
.person-link:hover { color: #f59e0b; text-decoration: underline; }

.section-cta {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  margin-top: 8px;
  font-size: 14px;
  font-weight: 700;
  color: #3b82f6;
}
.section-cta:hover { color: #2563eb; }
.section-cta .arrow { transition: transform 0.15s; }
.section-cta:hover .arrow { transform: translateX(3px); }

/* ── Topics of Interest (CFP page) ── */
.topics-sub {
  font-size: 16px;
  color: #64748b;
  margin-bottom: 20px;
}
.topics {
  display: flex;
  flex-direction: column;
  gap: 16px;
  margin-bottom: 32px;
}
.topic-card {
  background: #ffffff;
  border: 1px solid #e2e8f0;
  border-radius: 12px;
  padding: 20px 22px;
}
.topic-card-header {
  display: flex;
  align-items: flex-start;
  gap: 12px;
  margin-bottom: 8px;
}
.topic-num {
  flex-shrink: 0;
  width: 26px; height: 26px;
  background: rgba(245,158,11,0.15);
  border: 1px solid rgba(245,158,11,0.35);
  color: #d97706;
  font-size: 13px;
  font-weight: 700;
  border-radius: 6px;
  display: flex;
  align-items: center;
  justify-content: center;
}
.topic-title {
  font-size: 17px;
  font-weight: 700;
  color: #1e3a5f;
  line-height: 1.4;
}
.topic-focus {
  font-size: 14px;
  color: #94a3b8;
  margin-bottom: 10px;
  padding-left: 38px;
}
.topic-list {
  list-style: none;
  padding-left: 38px;
  display: flex;
  flex-direction: column;
  gap: 6px;
}
.topic-list li {
  font-size: 16px;
  color: #475569;
  line-height: 1.5;
  padding-left: 14px;
  position: relative;
}
.topic-list li::before {
  content: '';
  position: absolute;
  left: 0; top: 8px;
  width: 5px; height: 5px;
  background: #3b82f6;
  border-radius: 50%;
}

/* ── Footer ── */
.site-footer {
  background: #0f172a;
  color: #94a3b8;
  padding: 40px 24px;
  margin-top: 40px;
}
.footer-inner {
  max-width: var(--page-width);
  margin: 0 auto;
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  align-items: center;
  gap: 16px;
}
.footer-inner a {
  color: #cbd5e1;
  font-weight: 600;
}
.footer-inner a:hover { color: #fbbf24; }
.footer-copy {
  font-size: 13px;
  color: #64748b;
}

@media (max-width: 640px) {
  .nav { justify-content: center; text-align: center; }
  .nav-links { justify-content: center; }
  .footer-inner { flex-direction: column; text-align: center; }
}