:root {
  --bg: #f3f4f6;
  --surface: #fdfdfe;
  --surface-alt: #f4f6f9;
  --surface-soft: #eef1f5;
  --text: #161b22;
  --heading: #10151d;
  --muted: #4e5a68;
  --line: rgba(28, 37, 50, 0.16);
  --border: #d4dbe4;
  --border-strong: #b7c3d1;
  --osu-scarlet: #bb0000;
  --osu-scarlet-deep: #8f0000;
  --accent-ink: #263241;
  --link: #20364d;
  --link-hover: #0f2133;
  --focus: #bb0000;
  --radius-sm: 10px;
  --radius: 16px;
  --radius-lg: 22px;
  --shadow-soft: 0 10px 24px rgba(15, 23, 42, 0.06);
  --shadow-card: 0 16px 40px rgba(16, 24, 39, 0.09);
  --grid-pattern: radial-gradient(circle at 1px 1px, rgba(32, 48, 69, 0.14) 1px, transparent 0);
}

* { box-sizing: border-box; }

html, body { margin: 0; padding: 0; }

body {
  font-family: "Inter", "Avenir Next", "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  background:
    linear-gradient(180deg, rgba(255, 255, 255, 0.85), rgba(255, 255, 255, 0.85)),
    linear-gradient(135deg, #f6f7f9 0%, #eceff3 100%);
  color: var(--text);
  line-height: 1.65;
  letter-spacing: 0.003em;
}

img { max-width: 100%; height: auto; display: block; }

a {
  color: var(--link);
  text-underline-offset: 2px;
  text-decoration-thickness: 1px;
}

a:hover { color: var(--link-hover); }

:focus-visible {
  outline: 3px solid var(--focus);
  outline-offset: 3px;
  border-radius: 6px;
}

.skip-link {
  position: absolute;
  top: -48px;
  left: 10px;
  background: #111827;
  color: #fff;
  padding: 0.5rem 0.75rem;
  border-radius: 8px;
  z-index: 1000;
}

.skip-link:focus { top: 8px; }

.container {
  width: min(1120px, 92vw);
  margin-inline: auto;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  background: rgba(253, 253, 254, 0.92);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  min-height: 74px;
  gap: 1rem;
}

.brand {
  position: relative;
  display: inline-flex;
  align-items: center;
  gap: 0.72rem;
  text-decoration: none;
  color: var(--heading);
  font-weight: 700;
  letter-spacing: 0.01em;
}

.brand-mark {
  display: inline-grid;
  place-items: center;
  width: 2rem;
  height: 2rem;
  border-radius: 999px;
  border: 1.5px solid var(--border-strong);
  color: var(--osu-scarlet);
  font-size: 0.92rem;
  background:
    radial-gradient(circle at 30% 25%, rgba(187, 0, 0, 0.2), transparent 70%),
    #f9fafb;
}

.site-nav ul {
  display: flex;
  list-style: none;
  margin: 0;
  padding: 0;
  gap: 0.35rem;
  flex-wrap: wrap;
}

.site-nav a {
  display: inline-block;
  padding: 0.5rem 0.72rem;
  border-radius: 999px;
  text-decoration: none;
  color: var(--accent-ink);
  border: 1px solid transparent;
  transition: background-color 180ms ease, border-color 180ms ease, color 180ms ease;
}

.site-nav a:hover,
.site-nav a[aria-current='page'] {
  background: rgba(187, 0, 0, 0.08);
  border-color: rgba(187, 0, 0, 0.22);
  color: var(--osu-scarlet-deep);
}

.menu-toggle {
  display: none;
  border: 1px solid var(--border-strong);
  background: #fff;
  border-radius: 10px;
  padding: 0.42rem 0.74rem;
}

main { padding: 2.2rem 0 3.4rem; }
section { margin-block: 2rem; }

.hero {
  position: relative;
  background:
    linear-gradient(145deg, rgba(253, 253, 254, 0.92), rgba(245, 247, 250, 0.96)),
    var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-soft);
  padding: clamp(1.3rem, 4vw, 2.7rem);
  overflow: clip;
}

.hero::before,
.hero::after {
  content: "";
  position: absolute;
  pointer-events: none;
}

.hero::before {
  inset: 0;
  background-image: var(--grid-pattern);
  background-size: 18px 18px;
  opacity: 0.18;
  mask-image: linear-gradient(175deg, rgba(0, 0, 0, 0.7) 15%, transparent 75%);
}

.hero::after {
  top: -110px;
  right: -90px;
  width: 280px;
  height: 280px;
  border-radius: 50%;
  background: radial-gradient(circle at center, rgba(187, 0, 0, 0.14), transparent 70%);
}

.eyebrow {
  text-transform: uppercase;
  font-size: 0.78rem;
  letter-spacing: 0.1em;
  color: var(--muted);
}

h1, h2, h3 {
  line-height: 1.24;
  color: var(--heading);
  letter-spacing: -0.01em;
}

h1 {
  font-size: clamp(1.78rem, 4vw, 2.78rem);
  margin: 0.4rem 0 0.8rem;
}

h2 {
  font-size: clamp(1.3rem, 2.7vw, 1.92rem);
  margin: 0 0 0.85rem;
}

h3 {
  font-size: clamp(1.03rem, 2vw, 1.2rem);
  margin: 0 0 0.55rem;
}

p, li { color: var(--text); }

p { margin: 0 0 1rem; }

.muted { color: var(--muted); }

.status-note {
  display: inline-block;
  margin: 0.25rem 0 0;
  padding: 0.45rem 0.7rem;
  border-radius: 10px;
  background: rgba(187, 0, 0, 0.1);
  border: 1px solid rgba(187, 0, 0, 0.3);
  color: var(--osu-scarlet-deep);
  font-weight: 600;
}

.button-group {
  display: flex;
  flex-wrap: wrap;
  gap: 0.8rem;
  margin-top: 1.1rem;
}

.button {
  display: inline-block;
  background: linear-gradient(140deg, var(--osu-scarlet), #9f0000);
  color: #fff;
  border: 1px solid transparent;
  text-decoration: none;
  border-radius: 12px;
  padding: 0.66rem 1.05rem;
  font-weight: 620;
  letter-spacing: 0.004em;
  box-shadow: 0 8px 20px rgba(143, 0, 0, 0.24);
  transition: transform 180ms ease, box-shadow 180ms ease, filter 180ms ease;
}

.button:hover {
  color: #fff;
  transform: translateY(-1px);
  box-shadow: 0 12px 24px rgba(143, 0, 0, 0.27);
  filter: saturate(1.04);
}

.button-secondary {
  background: #ffffff;
  color: var(--accent-ink);
  border-color: var(--border-strong);
  box-shadow: none;
}

.button-secondary:hover {
  color: var(--osu-scarlet-deep);
  background: #f9fafb;
  border-color: rgba(187, 0, 0, 0.4);
}

.button.disabled,
.button[aria-disabled='true'] {
  background: #ced5df;
  border-color: #a4b0be;
  color: #2a3340;
  box-shadow: none;
  cursor: not-allowed;
  pointer-events: none;
}

.grid {
  display: grid;
  gap: 1.1rem;
}

.grid-2 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.grid-3 { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.grid-4 { grid-template-columns: repeat(4, minmax(0, 1fr)); }

.card {
  position: relative;
  background:
    linear-gradient(180deg, rgba(253, 253, 254, 0.96), rgba(246, 248, 251, 0.96)),
    var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow-card);
  overflow: hidden;
}

.card::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: linear-gradient(90deg, rgba(187, 0, 0, 0.75), rgba(187, 0, 0, 0.2), transparent);
  opacity: 0.7;
}

.card-body { padding: 1.1rem 1.12rem 1.2rem; }

.venue-map {
  border: 1px solid var(--border);
  border-radius: 12px;
  overflow: hidden;
  margin-bottom: 1rem;
}

.venue-map iframe {
  display: block;
  width: 100%;
  min-height: 320px;
  border: 0;
}

.person-card img {
  width: 100%;
  aspect-ratio: 4 / 3;
  object-fit: cover;
  background: #e8edf3;
  border-bottom: 1px solid var(--border);
}

.speaker-card img { aspect-ratio: 3 / 4; }

.speaker-card.no-crop img,
.organizer-card.no-crop img {
  object-fit: contain;
  background: #e8edf3;
}

.split {
  display: grid;
  grid-template-columns: 1.2fr 1fr;
  gap: 1.2rem;
}

.provisional-list {
  margin: 0;
  padding-left: 1.1rem;
}

.session-list {
  display: grid;
  gap: 0.9rem;
}

.session-item {
  border: 1px solid var(--border);
  border-radius: 12px;
  background:
    linear-gradient(170deg, rgba(255, 255, 255, 0.9), rgba(243, 246, 250, 0.94)),
    var(--surface-alt);
  padding: 0.92rem 1rem;
}

.session-time {
  display: inline-block;
  color: var(--osu-scarlet-deep);
  font-weight: 720;
  margin-bottom: 0.36rem;
  border-bottom: 1px solid rgba(187, 0, 0, 0.25);
}

.session-item p { margin: 0.42rem 0 0; }

.session-people {
  color: var(--muted);
  font-size: 0.95rem;
}

.site-footer {
  border-top: 1px solid var(--border);
  background: linear-gradient(180deg, rgba(253, 253, 254, 0.92), rgba(247, 249, 252, 0.96));
  padding: 1.38rem 0 1.95rem;
  color: var(--muted);
}

.footer-inner {
  display: grid;
  gap: 0.2rem;
}

.footer-inner p { margin: 0.2rem 0; }

@media (max-width: 900px) {
  .grid-4 { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .split,
  .grid-3,
  .grid-2 { grid-template-columns: 1fr; }
}

@media (max-width: 760px) {
  .menu-toggle { display: inline-block; }
  .site-nav { display: none; width: 100%; }
  .site-nav.open { display: block; }
  .header-inner { flex-wrap: wrap; padding: 0.58rem 0; }
  .site-nav ul { flex-direction: column; width: 100%; padding-bottom: 0.5rem; }
  .site-nav a {
    display: block;
    border-radius: 10px;
  }
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    scroll-behavior: auto !important;
    transition-duration: 0.01ms !important;
    animation-duration: 0.01ms !important;
  }
}