:root {
  --accent: #0091ff;
  --accent-dark: #0048a6;
  --accent-light: #e3f3ff;
  --accent-2: #ff9500;
  --accent-2-dark: #d97e00;
  --text: #222;
  --text-sec: #555;
  --text-dim: #888;
  --bg: #fff;
  --bg-alt: #f7f8fa;
  --border: #e0e0e0;
  --max-w: 960px;
  --radius: 12px;
}

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

html { scroll-behavior: smooth; scroll-padding-top: 64px; }

body {
  background: var(--bg);
  color: var(--text);
  font-family: 'Noto Sans', 'Segoe UI', system-ui, sans-serif;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
}

a { color: var(--accent); }

/* ═══ Top nav ═══ */
nav {
  position: sticky; top: 0; z-index: 100;
  background: rgba(255,255,255,0.92);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
  padding: 0 24px;
}
.nav-inner {
  max-width: var(--max-w);
  margin: 0 auto;
  display: flex; align-items: center;
  height: 56px;
}
.nav-brand {
  font-weight: 700; font-size: 0.95rem;
  color: var(--text); text-decoration: none;
  letter-spacing: -0.01em; margin-right: auto;
}
.nav-links { display: flex; align-items: center; gap: 28px; }
.nav-links a {
  color: var(--text-sec); text-decoration: none;
  font-size: 0.85rem; font-weight: 600;
  white-space: nowrap; padding: 18px 0;
  border-bottom: 2px solid transparent;
  transition: color 0.15s, border-color 0.15s;
}
.nav-links a:hover, .nav-links a.active {
  color: var(--accent); border-bottom-color: var(--accent);
}
.nav-toggle {
  display: none; flex-direction: column; gap: 5px;
  background: none; border: none; cursor: pointer; padding: 6px;
}
.nav-toggle span {
  width: 22px; height: 2px; background: var(--text);
  border-radius: 2px; transition: 0.2s;
}

/* ═══ Hero ═══ */
.hero {
  text-align: center;
  padding: 64px 24px 48px;
  border-bottom: 1px solid var(--border);
  background: linear-gradient(180deg, var(--accent-light) 0%, var(--bg) 70%);
}
.hero-icon {
  width: 180px; height: 180px; object-fit: contain;
  margin: 0 auto 18px; display: block;
}
.hero h1 {
  font-size: 2.1rem; font-weight: 700;
  letter-spacing: -0.02em; line-height: 1.25;
  max-width: 800px; margin: 0 auto 14px;
}
.hero-sub {
  font-size: 1.05rem; color: var(--text-sec);
  max-width: 680px; margin: 0 auto 24px;
}
.hero-meta {
  list-style: none;
  display: flex; flex-wrap: wrap; justify-content: center;
  gap: 10px 14px; max-width: 760px; margin: 0 auto 28px;
}
.hero-meta li {
  background: var(--bg); border: 1px solid var(--border);
  border-radius: 100px; padding: 7px 16px;
  font-size: 0.85rem; color: var(--text-sec);
}
.hero-meta .meta-label {
  font-weight: 700; color: var(--accent); margin-right: 4px;
}
.hero-links {
  display: flex; flex-wrap: wrap; justify-content: center; gap: 12px;
}
.hero-btn {
  display: inline-flex; align-items: center;
  padding: 9px 20px; border-radius: 8px;
  font-size: 0.88rem; font-weight: 600;
  text-decoration: none; white-space: nowrap;
  border: 1.5px solid var(--border);
  color: var(--text-sec); background: var(--bg);
  transition: background 0.15s, color 0.15s, border-color 0.15s, transform 0.15s;
}
.hero-btn:hover {
  background: var(--bg-alt); border-color: #bbb;
  color: var(--text); transform: translateY(-1px);
}
.hero-btn.primary {
  background: var(--accent); border-color: var(--accent); color: #fff;
}
.hero-btn.primary:hover {
  background: var(--accent-dark); border-color: var(--accent-dark); color: #fff;
}

/* ═══ Content / sections ═══ */
.content { max-width: var(--max-w); margin: 0 auto; padding: 0 24px; }
.section { padding: 56px 0; }
.section + .section { border-top: 1px solid var(--border); }
.section-title {
  font-size: 1.6rem; font-weight: 700;
  letter-spacing: -0.01em; margin-bottom: 18px;
  text-align: center;
}
.section-title::after {
  content: ""; display: block;
  width: 64px; height: 4px;
  background: var(--accent-2); border-radius: 100px;
  margin: 12px auto 0;
}
.section-subtitle {
  font-size: 0.95rem; color: var(--text-sec); margin-bottom: 28px;
  text-align: center;
}
.section p { margin-bottom: 16px; color: var(--text); }
.sub-head {
  font-size: 1.15rem; font-weight: 700;
  margin: 28px 0 12px;
}

/* ═══ CFP topics ═══ */
.topic-list {
  list-style: disc;
  padding-left: 1.4rem;
  margin: 8px 0 8px;
}
.topic-list li {
  font-size: 1.02rem; color: var(--text);
  margin-bottom: 8px; padding-left: 4px;
}
.topic-list li::marker { color: var(--accent); }

/* ═══ CFP cards ═══ */
.cfp-cards {
  display: grid; grid-template-columns: repeat(2, 1fr);
  gap: 18px; margin: 24px 0;
}
.cfp-card {
  background: var(--bg); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 20px 22px;
  box-shadow: 0 1px 4px rgba(0,0,0,0.04);
}
.cfp-card .sub-head { margin-top: 0; }
.cfp-list { list-style: none; }
.cfp-list li {
  font-size: 0.9rem; color: var(--text-sec);
  padding: 6px 0 6px 18px; position: relative;
}
.cfp-list li::before {
  content: ""; position: absolute; left: 0; top: 13px;
  width: 6px; height: 6px; border-radius: 50%; background: var(--accent);
}
.cfp-note {
  background: var(--accent-light); border-radius: var(--radius);
  padding: 16px 20px; font-size: 0.9rem; color: var(--text-sec);
  border: 1px solid #cfe3fb;
}

/* ═══ Important Dates — intuitive blocks ═══ */
.date-grid {
  display: grid; grid-template-columns: repeat(4, 1fr); gap: 16px;
}
.date-block {
  background: var(--bg); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 26px 18px; text-align: center;
  cursor: default;
  transition: background 0.2s, color 0.2s, border-color 0.2s, transform 0.2s, box-shadow 0.2s;
}
.date-block:hover {
  background: var(--accent); border-color: var(--accent); color: #fff;
  transform: translateY(-4px); box-shadow: 0 8px 22px rgba(21,101,192,0.28);
}
.date-day {
  font-size: 1.7rem; font-weight: 700; color: var(--accent);
  letter-spacing: -0.02em; transition: color 0.2s;
}
.date-block:hover .date-day { color: #fff; }
.date-year { font-size: 0.82rem; color: var(--text-dim); transition: color 0.2s; }
.date-block:hover .date-year { color: rgba(255,255,255,0.85); }
.date-label {
  margin-top: 10px; font-size: 0.9rem; font-weight: 600; color: var(--text);
  transition: color 0.2s;
}
.date-block:hover .date-label { color: #fff; }
.date-block.highlight {
  border-color: var(--accent); background: var(--accent-light);
}

/* ═══ People grids (speakers + organizers) ═══ */
.people-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 2rem;
  text-align: center;
  margin-top: 2rem;
}
.person-card {
  display: flex; flex-direction: column; align-items: center;
}
.person-img {
  width: 140px; height: 140px;
  object-fit: cover; object-position: top;
  border-radius: 50%;
  margin-bottom: 1rem;
  box-shadow: 0 4px 8px rgba(0,0,0,0.1);
  transition: transform 0.2s, box-shadow 0.2s;
}
.person-card:hover .person-img {
  transform: translateY(-3px);
  box-shadow: 0 8px 20px rgba(0,0,0,0.15);
}
.person-name { font-weight: 700; font-size: 0.95rem; }
.person-name a { color: var(--text); text-decoration: none; transition: color 0.15s; }
.person-name a:hover { color: var(--accent); }
.person-affil {
  display: inline-block; margin-top: 8px;
  font-size: 0.72rem; font-weight: 600;
  background: var(--accent-light); color: var(--accent-dark);
  padding: 3px 12px; border-radius: 100px;
}
.tag {
  display: inline-block; font-size: 0.65rem; font-weight: 600;
  background: var(--accent-light); color: var(--accent);
  padding: 1px 8px; border-radius: 100px; vertical-align: middle;
}

/* ═══ Schedule table ═══ */
.table-wrap { overflow-x: auto; border-radius: var(--radius); border: 1px solid var(--border); }
.schedule {
  width: 100%; border-collapse: collapse; font-size: 0.9rem;
  background: var(--bg); min-width: 560px;
}
.schedule thead th {
  background: var(--accent); color: #fff;
  text-align: left; font-weight: 600;
  padding: 12px 18px; font-size: 0.85rem;
}
.schedule td {
  padding: 12px 18px; border-top: 1px solid var(--border);
  color: var(--text-sec); vertical-align: top;
}
.schedule td:first-child { white-space: nowrap; font-weight: 600; color: var(--text); }
.schedule td:nth-child(2) { color: var(--text); }
.schedule tbody tr:nth-child(even) { background: var(--bg-alt); }
.schedule tbody tr:hover { background: var(--accent-light); }

/* ═══ Footer ═══ */
.footer {
  border-top: 1px solid var(--border);
  background: var(--bg-alt);
  padding: 40px 24px;
}
.footer-inner { max-width: var(--max-w); margin: 0 auto; text-align: center; }
.footer-title { font-weight: 700; font-size: 1rem; margin-bottom: 4px; }
.footer-sub { font-size: 0.85rem; color: var(--text-dim); margin-bottom: 10px; }
.footer-contact { font-size: 0.9rem; color: var(--text-sec); }
.footer-contact a { color: var(--accent); text-decoration: none; }
.footer-contact a:hover { text-decoration: underline; }

/* ═══ Responsive ═══ */
@media (max-width: 820px) {
  .cfp-cards { grid-template-columns: 1fr; }
  .date-grid { grid-template-columns: repeat(2, 1fr); }
}
@media (max-width: 640px) {
  .hero h1 { font-size: 1.6rem; }
  .nav-brand { font-size: 0.85rem; }
  .nav-toggle { display: flex; }
  .nav-links {
    position: absolute; top: 56px; left: 0; right: 0;
    flex-direction: column; align-items: stretch; gap: 0;
    background: rgba(255,255,255,0.98); backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--border);
    max-height: 0; overflow: hidden; transition: max-height 0.25s ease;
  }
  .nav-links.open { max-height: 360px; }
  .nav-links a { padding: 14px 24px; border-bottom: 1px solid var(--border); }
  .nav-links a:hover, .nav-links a.active { border-bottom-color: var(--border); }
  .people-grid { grid-template-columns: repeat(2, 1fr); }
}
@media (max-width: 420px) {
  .date-grid { grid-template-columns: 1fr; }
  .people-grid { grid-template-columns: 1fr; }
}