:root {
  --red: #d81f26;
  --ink: #16181d;
  --muted: #6b7280;
  --line: #e6e8ec;
}

* { box-sizing: border-box; }

html { -webkit-text-size-adjust: 100%; }

body {
  margin: 0;
  min-height: 100vh;
  overflow-x: hidden;
  display: flex;
  flex-direction: column;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  color: var(--ink);
  background: #fff;
  font-size: 13px;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

a { color: inherit; text-decoration: none; }

/* Top nav */
.site-header {
  position: sticky;
  top: 0;
  z-index: 20;
  background: rgba(255, 255, 255, 0.9);
  backdrop-filter: saturate(180%) blur(10px);
  border-bottom: 1px solid var(--line);
}
.nav-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  max-width: 900px;
  margin: 0 auto;
  height: 54px;
  padding: 0 24px;
}
.brand {
  font-weight: 800;
  letter-spacing: 0.14em;
  font-size: 12.5px;
}
.nav-btn {
  font: inherit;
  font-size: 12.5px;
  font-weight: 600;
  color: var(--ink);
  background: none;
  border: 0;
  padding: 6px 4px;
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  gap: 6px;
}
.nav-btn::after {
  content: "";
  width: 6px;
  height: 6px;
  border-right: 1.5px solid currentColor;
  border-bottom: 1.5px solid currentColor;
  transform: rotate(45deg);
  transition: transform 0.2s ease;
  margin-top: -3px;
}
.nav-btn[aria-expanded="true"] { color: var(--red); }
.nav-btn[aria-expanded="true"]::after { transform: rotate(-135deg); margin-top: 2px; }

.talks-panel {
  border-top: 1px solid var(--line);
  background: #fff;
}
.talks-panel[hidden] { display: none; }
.talks-panel-inner {
  max-width: 900px;
  margin: 0 auto;
  padding: 18px 24px 22px;
  display: flex;
  flex-direction: column;
  gap: 10px;
}
.talk {
  font-weight: 600;
  border-left: 3px solid var(--red);
  padding: 8px 0 8px 14px;
  transition: color 0.15s ease;
}
.talk:hover { color: var(--red); }

.stage {
  flex: 1;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 26px;
  padding: 56px 24px;
  text-align: center;
}

/* Crossfading logo */
.logo {
  position: relative;
  width: 320px;
  max-width: 80vw;
  aspect-ratio: 1 / 1;
  background: #fff;
  border-radius: 28px;
  overflow: hidden;
  border: 1px solid var(--line);
  box-shadow: 0 16px 40px rgba(0, 0, 0, 0.08);
}
.logo-img {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  object-fit: contain;
  opacity: 0;
  transform: scale(0.985);
  transition: opacity 1.1s ease, transform 1.1s ease;
}
.logo-img.is-active { opacity: 1; transform: scale(1); }

.tagline {
  margin: 0;
  color: var(--muted);
  letter-spacing: 0.02em;
}

.talks-label {
  margin: 0 0 4px;
  font-size: 11px;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--red);
  font-weight: 700;
}
.talks-label a {
  border-bottom: 1px solid transparent;
  transition: border-color 0.15s ease;
}
.talks-label a:hover { border-color: var(--red); }
.talks a {
  font-weight: 600;
  border-bottom: 1px solid transparent;
  padding-bottom: 1px;
  transition: color 0.15s ease, border-color 0.15s ease;
}
.talks a:hover { color: var(--red); border-color: var(--red); }

.site-footer {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 10px;
  padding: 26px 24px 32px;
  border-top: 1px solid var(--line);
  text-align: center;
}
.links {
  display: flex;
  gap: 20px;
  flex-wrap: wrap;
  justify-content: center;
  font-size: 12px;
  color: var(--muted);
}
.links a {
  border-bottom: 1px solid transparent;
  transition: color 0.15s ease, border-color 0.15s ease;
}
.links a:hover { color: var(--red); border-color: var(--red); }
.copyright {
  margin: 0;
  font-size: 11px;
  color: var(--muted);
}

/* ---------- Responsive ---------- */
@media (max-width: 600px) {
  .nav-inner { padding: 0 16px; height: 52px; }
  .brand { font-size: 11.5px; letter-spacing: 0.1em; }
  .nav-btn { font-size: 12px; }
  .talks-panel-inner { padding: 16px 16px 20px; }
  .talk { font-size: 12.5px; }
  .stage { padding: 40px 20px; gap: 22px; }
  .logo { width: 260px; border-radius: 24px; }
  .tagline { font-size: 12.5px; }
  .site-footer { padding: 22px 20px 28px; }
  .links { gap: 14px 18px; }
}

@media (max-width: 360px) {
  .brand { font-size: 11px; letter-spacing: 0.06em; }
  .logo { width: 220px; }
  .links { flex-direction: column; gap: 8px; }
}

/* Respect users who prefer no motion */
@media (prefers-reduced-motion: reduce) {
  .logo-img { transition: opacity 0.3s ease; transform: none; }
  .logo-img.is-active { transform: none; }
  .nav-btn::after { transition: none; }
}