*, *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: var(--font-sans);
  background: var(--bg);
  color: var(--fg);
  line-height: 1.55;
  -webkit-font-smoothing: antialiased;
}
img { max-width: 100%; display: block; }
a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }
h1, h2, h3, h4 { font-family: var(--font-display); line-height: 1.15; margin: 0 0 .6em; }
h1 { font-size: clamp(2.2rem, 5vw, 3.6rem); letter-spacing: -.02em; }
h2 { font-size: clamp(1.6rem, 3.2vw, 2.3rem); letter-spacing: -.01em; }
h3 { font-size: 1.15rem; }
p { margin: 0 0 1em; }
.container { width: min(100% - 2rem, var(--max-w)); margin-inline: auto; }
.narrow { max-width: 760px; }
.accent { color: var(--accent); }
.muted { color: var(--fg-muted); }
.skip-link {
  position: absolute; left: -9999px; top: 0; background: var(--accent);
  color: var(--accent-contrast); padding: .5rem .75rem; border-radius: 0 0 var(--radius-sm) 0;
}
.skip-link:focus { left: 0; }

/* Header / nav */
.site-header {
  position: sticky; top: 0; z-index: 50;
  background: color-mix(in srgb, var(--bg) 80%, transparent);
  backdrop-filter: saturate(140%) blur(10px);
  border-bottom: 1px solid var(--border);
}
.nav {
  display: flex; align-items: center; gap: 1rem;
  padding: .75rem 0;
}
.brand {
  display: inline-flex; align-items: center; gap: .6rem;
  color: var(--fg); text-decoration: none; font-weight: 600;
}
.brand-mark {
  width: 36px; height: 36px; border-radius: 10px;
  display: grid; place-items: center;
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  color: var(--accent-contrast); font-size: 1.1rem;
}
.brand-text strong { color: var(--accent); }
.primary-nav { margin-left: auto; display: flex; gap: 1.25rem; flex-wrap: wrap; }
.primary-nav a { color: var(--fg-muted); font-weight: 500; padding: .25rem 0; }
.primary-nav a:hover { color: var(--fg); text-decoration: none; }
.primary-nav a[aria-current="page"] { color: var(--accent); border-bottom: 2px solid var(--accent); }

.theme-switcher { display: inline-flex; align-items: center; gap: .5rem; margin-left: .5rem; }
.mode-toggle {
  width: 36px; height: 36px; border-radius: 999px; border: 1px solid var(--border);
  background: var(--bg-elev); color: var(--fg); cursor: pointer;
  display: grid; place-items: center; position: relative;
}
.mode-toggle .icon-sun, .mode-toggle .icon-moon { font-size: 1rem; line-height: 1; }
html[data-theme="dark"] .mode-toggle .icon-sun { display: none; }
html[data-theme="light"] .mode-toggle .icon-moon { display: none; }
.accent-picker { display: inline-flex; gap: .35rem; }
.accent-picker .swatch {
  width: 18px; height: 18px; border-radius: 999px; border: 2px solid transparent;
  cursor: pointer; padding: 0;
}
.accent-picker .swatch[data-accent="purple"] { background: #7c5cff; }
.accent-picker .swatch[data-accent="teal"]   { background: #1ec8b0; }
.accent-picker .swatch[data-accent="blue"]   { background: #4c8bff; }
.accent-picker .swatch[data-accent="orange"] { background: #ff7a45; }
.accent-picker .swatch[aria-pressed="true"] { border-color: var(--fg); }

.nav-toggle {
  display: none; width: 40px; height: 40px; border-radius: 8px;
  background: transparent; border: 1px solid var(--border); cursor: pointer;
  flex-direction: column; justify-content: center; align-items: center; gap: 4px;
}
.nav-toggle span { width: 20px; height: 2px; background: var(--fg); border-radius: 2px; }

/* Hero */
.hero { position: relative; overflow: hidden; }
.hero-bg {
  position: absolute; inset: 0; pointer-events: none;
  background: var(--hero-grad), var(--bg);
}
.hero-inner { position: relative; padding: clamp(3rem, 8vw, 6rem) 0 clamp(2.5rem, 5vw, 4rem); }
.eyebrow {
  display: inline-block; padding: .25rem .65rem; border-radius: 999px;
  background: color-mix(in srgb, var(--accent) 18%, transparent);
  color: var(--accent); font-size: .8rem; font-weight: 600; letter-spacing: .04em;
  text-transform: uppercase; margin: 0 0 1rem;
}
.lead { font-size: clamp(1.05rem, 1.6vw, 1.2rem); color: var(--fg-muted); max-width: 720px; }
.hero-meta { list-style: none; padding: 0; margin: 1.5rem 0 2rem; display: grid; gap: .35rem; }
.hero-meta strong { color: var(--accent); margin-right: .5rem; }
.cta-row { display: flex; gap: .75rem; flex-wrap: wrap; }
.btn {
  display: inline-flex; align-items: center; gap: .5rem;
  padding: .75rem 1.25rem; border-radius: 999px; font-weight: 600;
  border: 1px solid transparent; cursor: pointer; text-decoration: none;
  transition: transform .15s ease, box-shadow .15s ease, background .2s ease;
}
.btn:hover { transform: translateY(-1px); text-decoration: none; }
.btn-primary {
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  color: var(--accent-contrast);
  box-shadow: 0 8px 20px color-mix(in srgb, var(--accent) 35%, transparent);
}
.btn-ghost { background: var(--bg-elev); color: var(--fg); border-color: var(--border); }

.hero-stats {
  margin-top: 2.5rem; display: grid; grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 1rem; max-width: 520px;
}
.hero-stats > div {
  background: var(--bg-elev); border: 1px solid var(--border);
  border-radius: var(--radius-md); padding: 1rem; text-align: center;
}
.hero-stats span { font-family: var(--font-display); font-size: 1.6rem; font-weight: 700; color: var(--accent); }
.hero-stats small { display: block; color: var(--fg-muted); font-size: .8rem; text-transform: uppercase; letter-spacing: .08em; }

/* Sections */
.section { padding: clamp(3rem, 6vw, 5rem) 0; }
.section-alt { background: var(--bg-alt); }
.section-head { display: flex; justify-content: space-between; align-items: end; gap: 1rem; flex-wrap: wrap; margin-bottom: 1.5rem; }
.section-lead { color: var(--fg-muted); margin-top: -.4rem; }

/* Speakers grid */
.grid { display: grid; gap: 1.25rem; }
.speakers-grid { grid-template-columns: repeat(auto-fill, minmax(180px, 1fr)); }
.speaker {
  background: var(--bg-elev); border: 1px solid var(--border);
  border-radius: var(--radius-md); padding: 1rem; text-align: center;
  transition: transform .15s ease, box-shadow .15s ease, border-color .2s ease;
}
.speaker:hover { transform: translateY(-2px); box-shadow: var(--shadow-md); border-color: color-mix(in srgb, var(--accent) 50%, var(--border)); }
.speaker img {
  width: 100%; aspect-ratio: 1 / 1; object-fit: cover;
  border-radius: 50%; margin-bottom: .75rem;
  background: var(--bg-alt);
}
.speaker h3 { margin: 0 0 .25rem; font-size: 1rem; }
.speaker p { color: var(--fg-muted); font-size: .85rem; margin: 0; }

/* Schedule */
.schedule { display: grid; gap: .75rem; }
.schedule-item {
  display: grid; grid-template-columns: 110px 1fr; gap: 1rem;
  padding: 1rem; background: var(--bg-elev); border: 1px solid var(--border);
  border-radius: var(--radius-md);
}
.schedule-item .time { font-family: var(--font-display); font-weight: 700; color: var(--accent); }
.schedule-item .room { display: inline-block; font-size: .75rem; padding: .15rem .5rem; border-radius: 999px;
  background: color-mix(in srgb, var(--accent) 14%, transparent); color: var(--accent); margin-left: .5rem; }
.schedule-item h3 { margin: 0 0 .25rem; }
.schedule-item .speaker-name { color: var(--fg-muted); font-size: .9rem; }
.schedule-item.break { background: transparent; border-style: dashed; opacity: .85; }

/* Slides */
.slides-grid {
  display: grid; gap: 1rem;
  grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
}
.slide-card {
  display: flex; gap: 1rem; padding: 1rem;
  background: var(--bg-elev); border: 1px solid var(--border);
  border-radius: var(--radius-md);
  transition: transform .15s ease, box-shadow .15s ease, border-color .2s ease;
}
.slide-card:hover { transform: translateY(-2px); box-shadow: var(--shadow-md);
  border-color: color-mix(in srgb, var(--accent) 50%, var(--border)); }
.slide-thumb {
  position: relative; flex: 0 0 110px; height: 140px; padding: 0;
  border-radius: var(--radius-sm); border: 1px solid var(--border);
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  color: var(--accent-contrast); overflow: hidden; cursor: pointer;
  display: block;
}
.slide-thumb[disabled] { cursor: default; }
.slide-thumb img {
  width: 100%; height: 100%; object-fit: cover; display: block;
  background: #fff;
}
.slide-thumb .slide-badge {
  position: absolute; bottom: .35rem; left: .35rem;
  font-family: var(--font-display); font-weight: 700; font-size: .7rem;
  letter-spacing: .08em; padding: .15rem .45rem; border-radius: 4px;
  background: rgba(0, 0, 0, .55); color: #fff;
}
.slide-thumb.no-preview .slide-badge {
  position: static; background: transparent; font-size: .9rem;
  display: grid; place-items: center; width: 100%; height: 100%;
}
.slide-thumb:not([disabled]):hover img { transform: scale(1.03); transition: transform .25s ease; }
.slide-body { flex: 1; min-width: 0; }
.slide-body h3 { margin: 0 0 .25rem; font-size: 1rem; }
.slide-body .speaker-name { color: var(--fg-muted); font-size: .85rem; margin: 0 0 .4rem; }
.slide-body .muted { font-size: .85rem; margin: 0 0 .6rem; }
.tags { display: flex; flex-wrap: wrap; gap: .3rem; margin-bottom: .6rem; }
.tag {
  font-size: .7rem; padding: .15rem .55rem; border-radius: 999px;
  background: color-mix(in srgb, var(--accent) 14%, transparent);
  color: var(--accent); font-weight: 600; text-transform: uppercase; letter-spacing: .05em;
}
.slide-actions { display: flex; gap: .5rem; flex-wrap: wrap; }
.btn-sm { padding: .4rem .85rem; font-size: .85rem; }

/* Gallery */
.gallery {
  display: grid; gap: .6rem;
  grid-template-columns: repeat(auto-fill, minmax(150px, 1fr));
}
.gallery a {
  display: block; aspect-ratio: 1 / 1; overflow: hidden;
  border-radius: var(--radius-sm); background: var(--bg-elev);
  border: 1px solid var(--border);
}
.gallery img {
  width: 100%; height: 100%; object-fit: cover;
  transition: transform .35s ease;
}
.gallery a:hover img { transform: scale(1.06); }
.gallery .empty {
  grid-column: 1 / -1; text-align: center; color: var(--fg-muted);
  padding: 2rem; border: 1px dashed var(--border); border-radius: var(--radius-md);
}

/* Sponsors */
.sponsors {
  display: grid; gap: 1rem;
  grid-template-columns: repeat(auto-fill, minmax(160px, 1fr));
  align-items: center;
}
.sponsors a {
  display: grid; place-items: center;
  padding: 1.2rem; background: var(--bg-elev);
  border: 1px solid var(--border); border-radius: var(--radius-md);
  min-height: 90px; transition: border-color .2s ease, transform .15s ease;
}
.sponsors a:hover { border-color: color-mix(in srgb, var(--accent) 50%, var(--border)); transform: translateY(-2px); }
.sponsors img { max-height: 50px; width: auto; filter: none; }

/* Footer */
.site-footer { border-top: 1px solid var(--border); padding: 2rem 0; margin-top: 2rem; background: var(--bg); }
.footer-inner { display: flex; justify-content: space-between; gap: 1rem; flex-wrap: wrap; }
.footer-inner p { margin: 0; }

/* Lightbox */
.lightbox {
  border: 0; padding: 0; margin: auto;
  width: min(95vw, 1400px); max-width: none; height: min(92vh, 100%);
  background: transparent; color: #fff;
}
.lightbox::backdrop { background: rgba(0, 0, 0, .85); backdrop-filter: blur(6px); }
.lightbox .lb-img {
  width: 100%; height: 100%; object-fit: contain;
  border-radius: var(--radius-md);
}
.lightbox button {
  position: absolute; background: rgba(0, 0, 0, .55);
  color: #fff; border: 1px solid rgba(255, 255, 255, .15);
  border-radius: 999px; cursor: pointer;
  display: grid; place-items: center;
}
.lb-close { top: 1rem; right: 1rem; width: 40px; height: 40px; font-size: 1.4rem; }
.lb-prev, .lb-next { top: 50%; transform: translateY(-50%); width: 44px; height: 44px; font-size: 1.8rem; }
.lb-prev { left: 1rem; }
.lb-next { right: 1rem; }
.lb-caption {
  position: absolute; bottom: 1rem; left: 50%; transform: translateX(-50%);
  background: rgba(0, 0, 0, .55); padding: .35rem .75rem; border-radius: 999px;
  font-size: .85rem; margin: 0;
}

/* Slide viewer */
.slide-viewer {
  border: 0; padding: 0; margin: auto;
  width: min(96vw, 1200px); height: min(92vh, 900px);
  background: var(--bg-elev); color: var(--fg);
  border-radius: var(--radius-md); overflow: hidden;
  display: flex; flex-direction: column;
}
.slide-viewer[open] { display: flex; }
.slide-viewer::backdrop { background: rgba(0, 0, 0, .8); backdrop-filter: blur(6px); }
.slide-viewer .sv-header {
  display: flex; align-items: center; gap: 1rem; padding: .75rem 1rem;
  border-bottom: 1px solid var(--border); background: var(--bg);
}
.slide-viewer .sv-title { margin: 0; font-size: 1rem; flex: 1; min-width: 0;
  overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.slide-viewer .sv-actions { display: flex; gap: .4rem; flex-wrap: wrap; }
.slide-viewer iframe {
  flex: 1; width: 100%; border: 0; background: #1a1a1a; min-height: 0;
}

/* Responsive */
@media (max-width: 860px) {
  .primary-nav { display: none; position: absolute; top: 100%; left: 0; right: 0;
    background: var(--bg-elev); border-bottom: 1px solid var(--border);
    flex-direction: column; gap: 0; padding: .5rem 0; }
  .primary-nav.open { display: flex; }
  .primary-nav a { padding: .75rem 1.25rem; border-top: 1px solid var(--border); }
  .nav-toggle { display: inline-flex; }
  .theme-switcher { margin-left: auto; }
  .schedule-item { grid-template-columns: 1fr; }
}