:root {
  --bg: #000;
  --fg: #fff;
  --muted: rgba(255, 255, 255, 0.62);
  --accent: #3f81fd;
  --cyan: #19d3e0;
  --yellow: #ffd42d;
  --glass: rgba(255, 255, 255, 0.06);
  --glass-border: rgba(255, 255, 255, 0.14);
  --radius: 28px;
  --font: 'Manrope', 'Helvetica Neue', Arial, sans-serif;
}

*, *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; scroll-padding-top: 80px; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--fg);
  font-family: var(--font);
  font-size: 18px;
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
}
img { max-width: 100%; display: block; }
a { color: inherit; }
ul { list-style: none; margin: 0; padding: 0; }
dl, dd, p { margin: 0; }

.container { width: min(1200px, 100% - 32px); margin-inline: auto; }

/* Header */
.header {
  position: sticky; top: 0; z-index: 10;
  background: rgba(0, 0, 0, 0.72);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  border-bottom: 1px solid rgba(255, 255, 255, 0.08);
}
.header__inner {
  width: min(1200px, 100% - 32px); margin-inline: auto;
  display: flex; align-items: center; justify-content: space-between; gap: 24px;
  height: 64px;
}
.logo { display: inline-flex; align-items: center; gap: 10px; font-weight: 800; font-size: 20px; letter-spacing: -0.03em; text-decoration: none; }
.logo__tux { image-rendering: pixelated; }
.nav { display: flex; gap: 28px; font-size: 15px; font-weight: 600; }
.nav a { text-decoration: none; color: var(--muted); transition: color .2s; }
.nav a:hover, .nav a:focus-visible { color: var(--fg); }

/* Hero */
.hero {
  display: grid; place-items: center; text-align: center;
  padding: clamp(56px, 8vw, 104px) 16px clamp(24px, 4vw, 48px);
}
.hero__content { max-width: 1400px; }
.hero__date { font-size: clamp(18px, 2.4vw, 32px); font-weight: 500; letter-spacing: -0.02em; }

.hero__lead { margin: 0.6em auto 0; max-width: 560px; font-size: clamp(16px, 1.8vw, 24px); font-weight: 500; line-height: 1.3; }
.hero__actions { margin-top: 40px; display: flex; flex-wrap: wrap; gap: 12px; justify-content: center; }

.btn {
  display: inline-block; padding: 16px 28px; border-radius: 999px;
  font-size: 16px; font-weight: 700; text-decoration: none;
  transition: transform .2s, background-color .2s, border-color .2s;
}
.btn:hover { transform: translateY(-2px); }
.btn--primary { background: var(--accent); color: #fff; }
.btn--primary:hover { background: #5b95ff; }
.btn--ghost { border: 1px solid rgba(255, 255, 255, 0.4); }
.btn--ghost:hover { border-color: #fff; }

/* RULKC banner with the penguin */
.rulkc-strip { padding: clamp(24px, 3vw, 40px) 16px 0; position: relative; }
.rulkc-banner {
  position: relative; display: flex; align-items: center; gap: clamp(20px, 4vw, 64px);
  width: min(1200px, 100%); margin-inline: auto;
  padding: clamp(24px, 3.2vw, 44px) clamp(24px, 5vw, 80px);
  border-radius: var(--radius); overflow: hidden;
  background: url('assets/glass-card.png') center / 100% 100% no-repeat, #050507;
  text-decoration: none;
  transition: transform .3s;
}
.rulkc-banner:hover { transform: translateY(-3px); }
.rulkc-banner__tux { width: clamp(84px, 12vw, 168px); height: auto; image-rendering: pixelated; flex: none; }
.rulkc-banner__body { display: flex; flex-direction: column; gap: 14px; flex: 1 1 0; min-width: 0; container-type: inline-size; }
.rulkc-banner__title { font-size: clamp(16px, 3.3vw, 52px); font-size: clamp(16px, 6.1cqw, 60px); font-weight: 600; line-height: 1.1; letter-spacing: -0.05em; }
.rulkc-banner__title span { display: block; color: var(--yellow); white-space: nowrap; }
.rulkc-banner__logo { width: min(100%, clamp(280px, 38vw, 540px)); height: auto; }

.sr-only { position: absolute; width: 1px; height: 1px; margin: -1px; padding: 0; overflow: hidden; clip: rect(0, 0, 0, 0); white-space: nowrap; border: 0; }

/* Sections */
.section { padding: clamp(64px, 9vw, 120px) 0; }
.section--tinted { background: radial-gradient(900px 400px at 100% 0%, rgba(63, 129, 253, 0.16), transparent 70%), radial-gradient(700px 400px at 0% 100%, rgba(25, 211, 224, 0.10), transparent 70%); }
.section__title { font-size: clamp(32px, 4.4vw, 50px); font-weight: 800; line-height: 1.1; letter-spacing: -0.04em; margin-bottom: clamp(32px, 4vw, 56px); }

.grid { display: grid; gap: 20px; }
.grid--3 { grid-template-columns: repeat(3, 1fr); }
.grid--2 { grid-template-columns: repeat(2, 1fr); }

.card {
  position: relative; display: flex; flex-direction: column; gap: 16px; justify-content: flex-end;
  min-height: 190px; padding: 28px;
  border-radius: var(--radius);
  background: var(--glass); border: 1px solid var(--glass-border);
  font-size: 20px; font-weight: 600; line-height: 1.25; letter-spacing: -0.02em;
  overflow: hidden;
}
.card__num { margin-bottom: auto; color: var(--accent); font-size: 16px; font-weight: 700; letter-spacing: 0; }
.card--glow::before {
  content: ''; position: absolute; inset: 0; z-index: 0; pointer-events: none;
  background: radial-gradient(260px 200px at 0% 100%, rgba(25, 211, 224, 0.38), transparent 70%), radial-gradient(240px 180px at 100% 0%, rgba(63, 129, 253, 0.45), transparent 70%);
}
.card--glow { z-index: 0; justify-content: flex-start; min-height: 132px; padding: 24px 28px; font-size: 19px; }
.card--glow > * { position: relative; }
.card--link { text-decoration: none; min-height: 200px; transition: transform .3s, border-color .3s; }
.card--link:hover { transform: translateY(-3px); border-color: var(--accent); }
.card__year { margin-bottom: auto; font-size: clamp(40px, 6vw, 72px); font-weight: 800; letter-spacing: -0.05em; color: var(--accent); line-height: 1; }

/* Date & place */
.facts { display: grid; grid-template-columns: repeat(2, 1fr); gap: 20px; }
.fact { padding: 32px; border-radius: var(--radius); background: var(--glass); border: 1px solid var(--glass-border); }
.fact dt { color: var(--muted); font-size: 16px; font-weight: 600; margin-bottom: 12px; }
.fact__sub { margin-top: 10px; color: var(--muted); font-size: 16px; line-height: 1.4; }
.fact__value { font-size: clamp(28px, 3.6vw, 44px); font-weight: 800; letter-spacing: -0.04em; line-height: 1.1; }

/* Route scheme */
.route { display: grid; grid-template-columns: 1.05fr 0.95fr; gap: clamp(20px, 4vw, 56px); align-items: center; margin-top: 20px; padding: clamp(24px, 3.5vw, 48px); border-radius: var(--radius); background: var(--glass); border: 1px solid var(--glass-border); }
.route__title { margin: 0 0 16px; font-size: clamp(26px, 3vw, 36px); font-weight: 800; letter-spacing: -0.04em; line-height: 1.1; }
.route__lead { font-size: clamp(18px, 2vw, 22px); line-height: 1.4; }
.route__lead b { font-weight: 700; color: var(--yellow); }
.route__actions { display: flex; flex-wrap: wrap; gap: 12px; margin-top: 28px; }
.route__scheme { position: relative; margin: 0; justify-self: center; width: 100%; max-width: 400px; border-radius: 24px; overflow: hidden; background: #0b0b0e; border: 1px solid var(--glass-border); }
.route__basemap { display: block; width: 100%; height: auto; }
.route__svg { position: absolute; inset: 0; width: 100%; height: 100%; font-family: inherit; }
.route__attr { position: absolute; right: 8px; bottom: 6px; padding: 2px 8px; border-radius: 8px; background: rgba(0, 0, 0, 0.6); color: rgba(255, 255, 255, 0.7); font-size: 10.5px; line-height: 1.4; }
.route__attr a { text-decoration: underline; text-underline-offset: 2px; }
.route__dash { animation: route-walk 1.6s linear infinite; }
@keyframes route-walk { to { stroke-dashoffset: -9.1; } }

/* Schedule: two tracks */
.tracks-tabs { display: inline-flex; gap: 4px; padding: 4px; margin-bottom: 24px; border-radius: 999px; background: var(--glass); border: 1px solid var(--glass-border); }
.tracks-tabs__btn { padding: 10px 20px; border: 0; border-radius: 999px; background: transparent; color: var(--muted); font: inherit; font-size: 15px; font-weight: 700; cursor: pointer; transition: background-color .2s, color .2s; }
.tracks-tabs__btn:hover { color: var(--fg); }
.tracks-tabs__btn.is-active { background: var(--accent); color: #fff; }
.tracks { display: grid; grid-template-columns: repeat(2, 1fr); gap: 20px; }
.tracks[data-filter="1"] > [data-track="2"], .tracks[data-filter="2"] > [data-track="1"] { display: none; }
.tracks[data-filter="1"], .tracks[data-filter="2"] { grid-template-columns: 1fr; }
.schedule { border-radius: var(--radius); background: var(--glass); border: 1px solid var(--glass-border); padding: 28px 32px 12px; }
.schedule__title { margin: 0 0 8px; font-size: 28px; font-weight: 800; letter-spacing: -0.04em; }
.schedule__row { display: flex; gap: 24px; align-items: baseline; padding: 20px 0; border-top: 1px dashed rgba(255, 255, 255, 0.16); font-size: 18px; font-weight: 600; }
.schedule__time { color: var(--accent); font-variant-numeric: tabular-nums; min-width: 64px; }
.schedule__talk { color: rgba(255, 255, 255, 0.35); }
.schedule__note { margin-top: 24px; color: var(--muted); font-size: 16px; }
.schedule__note a, .footer a { text-decoration-color: rgba(255, 255, 255, 0.35); text-underline-offset: 3px; }
.schedule__note a:hover, .footer a:hover { text-decoration-color: var(--accent); color: var(--accent); }

/* Call for papers */
.cfp { display: grid; grid-template-columns: 1fr 1.4fr; gap: clamp(32px, 6vw, 80px); align-items: start; }
.cfp__text { color: var(--muted); font-size: 20px; line-height: 1.4; }
.cfp__card { display: grid; gap: 16px; justify-items: start; padding: clamp(24px, 3vw, 40px); border-radius: var(--radius); background: var(--glass); border: 1px solid var(--glass-border); }
.cfp__card-title { font-size: clamp(22px, 2.6vw, 30px); font-weight: 800; letter-spacing: -0.03em; line-height: 1.15; }
.cfp__card-text { color: var(--muted); font-size: 17px; line-height: 1.45; }
.cfp__deadline { display: inline-block; padding: 6px 14px; border-radius: 999px; background: rgba(255, 212, 45, 0.12); border: 1px solid rgba(255, 212, 45, 0.4); color: var(--yellow); font-size: 15px; font-weight: 700; }
.cfp__card .btn { margin-top: 8px; }

/* Program committee */
.people { display: grid; grid-template-columns: repeat(4, 1fr); gap: 20px; }
.person { padding: 24px; border-radius: var(--radius); background: var(--glass); border: 1px solid var(--glass-border); }
.person__photo { width: 112px; height: 112px; margin-bottom: 20px; border-radius: 50%; object-fit: cover; border: 3px solid var(--accent); }
.person__name { font-size: 20px; font-weight: 700; letter-spacing: -0.03em; line-height: 1.2; }
.person__company { margin-top: 6px; color: var(--accent); font-size: 15px; font-weight: 600; }
.person__role { margin-top: 4px; color: var(--muted); font-size: 15px; line-height: 1.35; }

/* Socials */
.socials { display: grid; grid-template-columns: repeat(3, 1fr); gap: 20px; }
.social {
  display: grid; grid-template-columns: 64px 1fr; grid-template-rows: auto auto; column-gap: 20px; align-items: center;
  height: 100%; padding: 24px; border-radius: var(--radius);
  background: var(--glass); border: 1px solid var(--glass-border);
  text-decoration: none; transition: transform .3s, border-color .3s, background-color .3s;
}
.social:hover, .social:focus-visible { transform: translateY(-3px); border-color: var(--accent); background: rgba(63, 129, 253, 0.12); }
.social__icon {
  grid-row: 1 / 3; display: grid; place-items: center; width: 64px; height: 64px;
  border-radius: 20px; background: var(--accent); font-size: 20px; font-weight: 800; letter-spacing: -0.02em;
}
.social__name { font-size: 22px; font-weight: 700; letter-spacing: -0.03em; align-self: end; }
.social__hint { color: var(--muted); font-size: 15px; align-self: start; }

/* Footer */
.footer { border-top: 1px solid rgba(255, 255, 255, 0.1); padding: 48px 0; font-size: 16px; }
.footer__inner { display: flex; flex-wrap: wrap; justify-content: space-between; gap: 32px; }
.footer__brand { font-size: 24px; font-weight: 800; letter-spacing: -0.04em; margin-bottom: 6px; }
.footer__muted { color: var(--muted); }

/* Reveal on scroll */
.reveal { opacity: 0; transform: translateY(24px); transition: opacity .7s ease, transform .7s ease; }
.reveal.is-visible { opacity: 1; transform: none; }
.rulkc-banner.reveal.is-visible:hover { transform: translateY(-3px); }
.card--link.reveal.is-visible:hover, .social:hover { transform: translateY(-3px); }

:focus-visible { outline: 2px solid var(--cyan); outline-offset: 3px; }

@media (max-width: 960px) {
  .cfp { grid-template-columns: 1fr; }
  .grid--3, .socials, .people { grid-template-columns: repeat(2, 1fr); }
}
@media (max-width: 640px) {
  body { font-size: 16px; }
  .nav { display: none; }
  .grid--3, .grid--2, .socials, .facts { grid-template-columns: 1fr; }
  .cfp__card .btn, .route__actions .btn { width: 100%; text-align: center; }
  .route { grid-template-columns: 1fr; }
  .people { grid-template-columns: repeat(2, 1fr); gap: 12px; }
  .person { padding: 16px; }
  .person__photo { width: 80px; height: 80px; }
  .person__name { font-size: 17px; }
  .card { min-height: 150px; padding: 24px; font-size: 18px; }
  .card--glow { min-height: 0; padding: 22px 24px; font-size: 18px; }
  .rulkc-banner { flex-direction: column; align-items: flex-start; }
  .rulkc-banner__body { flex: none; width: 100%; }
  .tracks { grid-template-columns: 1fr; }
  .schedule { padding: 20px 20px 4px; }
  .schedule__row { gap: 16px; font-size: 16px; }
  .hero__actions .btn { width: 100%; text-align: center; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .route__dash { animation: none; }
  .reveal { opacity: 1; transform: none; transition: none; }
}

/* Legal pages */
.legal { max-width: 820px; padding: clamp(40px, 6vw, 80px) 0; font-size: 17px; line-height: 1.6; }
.legal__title { font-size: clamp(28px, 4vw, 44px); font-weight: 800; line-height: 1.12; letter-spacing: -0.04em; margin-bottom: 32px; }
.legal h2 { font-size: 22px; font-weight: 800; letter-spacing: -0.03em; margin: 36px 0 12px; }
.legal p { margin-bottom: 12px; }
.legal ul, .legal ol { margin: 0 0 14px; padding-left: 22px; }
.legal li { margin-bottom: 6px; }
.legal strong { font-weight: 700; }
.ph { background: var(--yellow); color: #000; padding: 0 3px; border-radius: 3px; }
.footer__inner p + p { margin-top: 4px; }
.legal a { color: var(--accent); text-decoration: underline; text-decoration-color: rgba(63, 129, 253, 0.45); text-underline-offset: 3px; overflow-wrap: anywhere; }
.legal a:hover { text-decoration-color: var(--accent); }
@media (max-width: 640px) { .nav.nav--back { display: flex; } }