/* ==========================================================================
   20 Under 20 — US–China AI Innovators & Impact Awards
   Cinematic flagship page. Shares brand tokens with style.css
   (--red #D73D28, --dark #1F232C, Montserrat) on a dark film-grade canvas.
   Spacing: 8px grid. Reveals are CSS-driven; js/20under20.js adds .in.
   ========================================================================== */

:root {
  --u20-bg: #14171E;
  --u20-surface: #1F232C;
  --u20-surface-2: #262B36;
  --u20-line: rgba(255, 255, 255, 0.10);
  --u20-text: rgba(255, 255, 255, 0.92);
  --u20-muted: rgba(255, 255, 255, 0.62);
  --u20-faint: rgba(255, 255, 255, 0.38);
  --u20-red: #D73D28;
  --u20-red-bright: #F04E36;
  --zh-stack: 'Montserrat', 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', 'Noto Sans SC', sans-serif;
}

html.u20-root { scroll-behavior: auto; } /* Lenis owns scrolling */
html.lenis { height: auto; }
.lenis.lenis-smooth { scroll-behavior: auto !important; }

body.u20 {
  background: var(--u20-bg);
  color: var(--u20-text);
  font-family: var(--zh-stack);
  overflow-x: hidden;
}

/* Language toggle: html[lang] decides which copy shows */
html[lang="en"] .zh { display: none !important; }
html[lang="zh-CN"] .en { display: none !important; }

.u20 ::selection { background: var(--u20-red); color: #fff; }

/* ---------- Shared layout ---------- */
.u20-wrap { max-width: 1160px; margin: 0 auto; padding: 0 24px; }
.u20-section { padding: 128px 0; position: relative; }
.u20-eyebrow {
  display: inline-block;
  font-size: 13px;
  font-weight: 600;
  letter-spacing: 0.22em;
  text-transform: uppercase;
  color: var(--u20-red-bright);
  margin-bottom: 24px;
}
.u20-h2 {
  font-size: clamp(34px, 4.6vw, 56px);
  font-weight: 800;
  letter-spacing: -0.02em;
  line-height: 1.06;
  margin-bottom: 24px;
}
.u20-lead {
  font-size: 18px;
  line-height: 1.75;
  color: var(--u20-muted);
  max-width: 62ch;
}

/* ---------- Reveal-on-scroll ---------- */
.reveal { opacity: 0; transform: translateY(28px); transition: opacity 0.6s ease-out, transform 0.6s ease-out; }
.reveal.in { opacity: 1; transform: none; }
.reveal-stagger > * { opacity: 0; transform: translateY(24px); transition: opacity 0.55s ease-out, transform 0.55s ease-out; }
.reveal-stagger.in > * { opacity: 1; transform: none; }
.reveal-stagger.in > *:nth-child(2) { transition-delay: 0.08s; }
.reveal-stagger.in > *:nth-child(3) { transition-delay: 0.16s; }
.reveal-stagger.in > *:nth-child(4) { transition-delay: 0.24s; }
.reveal-stagger.in > *:nth-child(5) { transition-delay: 0.32s; }
.reveal-stagger.in > *:nth-child(6) { transition-delay: 0.40s; }

@media (prefers-reduced-motion: reduce) {
  .reveal, .reveal-stagger > * { opacity: 1 !important; transform: none !important; transition: none !important; }
  .u20-scroll-cue { display: none; }
}

/* ---------- Header (overlay) ---------- */
.u20-header {
  position: fixed;
  top: 0; left: 0; right: 0;
  z-index: 200;
  transition: background 0.35s ease, box-shadow 0.35s ease;
}
.u20-header.scrolled {
  background: rgba(20, 23, 30, 0.82);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  box-shadow: 0 1px 0 var(--u20-line);
}
.u20-header-inner {
  max-width: 1280px;
  margin: 0 auto;
  padding: 16px 24px;
  display: flex;
  align-items: center;
  gap: 32px;
}
.u20-header-logo { display: flex; align-items: center; gap: 12px; }
.u20-header-logo img { height: 34px; width: auto; }
.u20-header-logo span {
  font-size: 12px;
  font-weight: 600;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--u20-faint);
}
.u20-nav { margin-left: auto; display: flex; align-items: center; gap: 28px; }
.u20-nav a { font-size: 13.5px; font-weight: 500; color: var(--u20-muted); transition: color 0.2s; }
.u20-nav a:hover { color: #fff; }
.u20-lang-toggle {
  border: 1px solid var(--u20-line);
  border-radius: 999px;
  background: transparent;
  color: var(--u20-muted);
  font-family: var(--zh-stack);
  font-size: 12.5px;
  font-weight: 600;
  padding: 7px 16px;
  cursor: pointer;
  transition: color 0.2s, border-color 0.2s;
}
.u20-lang-toggle:hover { color: #fff; border-color: rgba(255, 255, 255, 0.35); }
.u20-btn {
  display: inline-block;
  background: var(--u20-red);
  color: #fff;
  font-size: 14px;
  font-weight: 600;
  padding: 12px 28px;
  border: none;
  border-radius: 6px;
  cursor: pointer;
  font-family: var(--zh-stack);
  transition: background 0.25s, transform 0.25s, box-shadow 0.25s;
}
.u20-btn:hover { background: var(--u20-red-bright); transform: translateY(-2px); box-shadow: 0 10px 28px rgba(215, 61, 40, 0.35); }
.u20-btn:focus-visible { outline: 2px solid #fff; outline-offset: 3px; }
.u20-btn-ghost {
  background: transparent;
  border: 1px solid rgba(255, 255, 255, 0.35);
  box-shadow: none;
}
.u20-btn-ghost:hover { background: rgba(255, 255, 255, 0.08); box-shadow: none; }
.u20-header .u20-btn { padding: 10px 22px; font-size: 13px; }

/* ---------- Hero ---------- */
.u20-hero {
  position: relative;
  min-height: 100vh;
  min-height: 100svh;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  overflow: hidden;
}
.u20-hero-media {
  position: absolute;
  inset: 0;
  z-index: 0;
  /* Intentional fallback when video is absent: slow-breathing brand gradient */
  background:
    radial-gradient(120% 90% at 20% 110%, rgba(215, 61, 40, 0.34), transparent 55%),
    radial-gradient(110% 80% at 85% -10%, rgba(64, 84, 128, 0.4), transparent 60%),
    linear-gradient(175deg, #10131a 0%, #171b25 55%, #1a1410 100%);
}
.u20-hero-media video {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
}
.u20-hero-media::after {
  /* film vignette + legibility scrim */
  content: "";
  position: absolute;
  inset: 0;
  background:
    linear-gradient(180deg, rgba(20, 23, 30, 0.55) 0%, rgba(20, 23, 30, 0.18) 35%, rgba(20, 23, 30, 0.28) 70%, var(--u20-bg) 100%);
  pointer-events: none;
}
.u20-hero-content { position: relative; z-index: 2; padding: 140px 24px 96px; max-width: 1000px; }
.u20-hero-eyebrow {
  font-size: 13px;
  font-weight: 600;
  letter-spacing: 0.3em;
  text-transform: uppercase;
  color: rgba(255, 255, 255, 0.75);
  margin-bottom: 32px;
}
.u20-hero h1 {
  font-size: clamp(64px, 12vw, 168px);
  font-weight: 800;
  letter-spacing: -0.03em;
  line-height: 0.94;
  margin-bottom: 16px;
  text-shadow: 0 8px 60px rgba(0, 0, 0, 0.45);
}
.u20-hero h1 .accent { color: var(--u20-red-bright); }
.u20-hero-sub {
  font-size: clamp(18px, 2.4vw, 26px);
  font-weight: 600;
  letter-spacing: 0.06em;
  margin-bottom: 20px;
}
.u20-hero-tagline {
  font-size: 16px;
  line-height: 1.7;
  color: rgba(255, 255, 255, 0.75);
  max-width: 56ch;
  margin: 0 auto 40px;
}
.u20-hero-ctas { display: flex; gap: 16px; justify-content: center; flex-wrap: wrap; }

/* staggered entrance */
.u20-hero-content > * { opacity: 0; transform: translateY(26px); animation: u20-rise 0.7s ease-out forwards; }
.u20-hero-content > *:nth-child(1) { animation-delay: 0.15s; }
.u20-hero-content > *:nth-child(2) { animation-delay: 0.3s; }
.u20-hero-content > *:nth-child(3) { animation-delay: 0.45s; }
.u20-hero-content > *:nth-child(4) { animation-delay: 0.6s; }
.u20-hero-content > *:nth-child(5) { animation-delay: 0.75s; }
@keyframes u20-rise { to { opacity: 1; transform: none; } }
@media (prefers-reduced-motion: reduce) {
  .u20-hero-content > * { animation: none; opacity: 1; transform: none; }
}

.u20-scroll-cue {
  position: absolute;
  bottom: 32px;
  left: 50%;
  transform: translateX(-50%);
  z-index: 2;
  width: 24px;
  height: 40px;
  border: 2px solid rgba(255, 255, 255, 0.4);
  border-radius: 14px;
}
.u20-scroll-cue::before {
  content: "";
  position: absolute;
  top: 7px; left: 50%;
  width: 4px; height: 8px;
  margin-left: -2px;
  border-radius: 2px;
  background: rgba(255, 255, 255, 0.75);
  animation: u20-cue 1.8s ease-in-out infinite;
}
@keyframes u20-cue {
  0%, 100% { transform: translateY(0); opacity: 1; }
  60% { transform: translateY(12px); opacity: 0; }
}

/* ---------- Stats strip ---------- */
.u20-stats { border-top: 1px solid var(--u20-line); border-bottom: 1px solid var(--u20-line); }
.u20-stats-grid { display: grid; grid-template-columns: repeat(4, 1fr); }
.u20-stat { text-align: center; padding: 48px 16px; }
.u20-stat + .u20-stat { border-left: 1px solid var(--u20-line); }
.u20-stat b { display: block; font-size: clamp(36px, 4.5vw, 56px); font-weight: 800; letter-spacing: -0.02em; color: #fff; line-height: 1.1; }
.u20-stat span { font-size: 13.5px; color: var(--u20-muted); margin-top: 8px; display: inline-block; }

/* ---------- Mission ---------- */
.u20-mission .u20-h2 { max-width: 21ch; }
.u20-mission-grid { display: grid; grid-template-columns: 1.15fr 0.85fr; gap: 64px; align-items: start; }
.u20-mission-side { border-left: 2px solid var(--u20-red); padding-left: 28px; display: flex; flex-direction: column; gap: 24px; }
.u20-mission-side p { font-size: 15.5px; line-height: 1.75; color: var(--u20-muted); }
.u20-mission-side strong { color: var(--u20-text); font-weight: 600; }

/* ---------- Categories ---------- */
.u20-cats-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
  margin-top: 56px;
}
.u20-cat {
  background: var(--u20-surface);
  border: 1px solid var(--u20-line);
  border-radius: 14px;
  padding: 32px 28px;
  transition: transform 0.3s ease, border-color 0.3s ease, background 0.3s ease;
}
.u20-cat:hover { transform: translateY(-5px); border-color: rgba(240, 78, 54, 0.45); background: var(--u20-surface-2); }
.u20-cat-icon {
  width: 44px; height: 44px;
  border-radius: 10px;
  background: rgba(215, 61, 40, 0.14);
  display: flex; align-items: center; justify-content: center;
  margin-bottom: 20px;
}
.u20-cat-icon svg { width: 22px; height: 22px; stroke: var(--u20-red-bright); }
.u20-cat h3 { font-size: 19px; font-weight: 700; margin-bottom: 10px; letter-spacing: -0.01em; }
.u20-cat p { font-size: 14px; line-height: 1.65; color: var(--u20-muted); }

/* ---------- Scroll-scrubbed film section ---------- */
.u20-film { position: relative; height: 320vh; }
.u20-film-sticky {
  position: sticky;
  top: 0;
  height: 100vh;
  height: 100svh;
  overflow: hidden;
  display: flex;
  align-items: flex-end;
}
.u20-film-media {
  position: absolute;
  inset: 0;
  background:
    radial-gradient(100% 80% at 80% 100%, rgba(215, 61, 40, 0.28), transparent 55%),
    linear-gradient(200deg, #0f1218 0%, #1b202b 60%, #12151c 100%);
}
.u20-film-media video { width: 100%; height: 100%; object-fit: cover; display: block; }
.u20-film-media::after {
  content: "";
  position: absolute;
  inset: 0;
  background: linear-gradient(180deg, var(--u20-bg) 0%, transparent 22%, transparent 60%, rgba(16, 19, 26, 0.82) 100%);
  pointer-events: none;
}
.u20-film-captions { position: relative; z-index: 2; width: 100%; padding: 0 24px 12vh; }
.u20-film-caption {
  position: absolute;
  bottom: 12vh; left: 0; right: 0;
  margin: 0 auto;
  max-width: 880px;
  padding: 0 24px;
  text-align: center;
  opacity: 0;
  transform: translateY(20px);
  transition: opacity 0.45s ease-out, transform 0.45s ease-out;
  pointer-events: none;
}
.u20-film-caption.active { opacity: 1; transform: none; }
.u20-film-caption .num {
  display: block;
  font-size: 13px;
  font-weight: 600;
  letter-spacing: 0.26em;
  color: var(--u20-red-bright);
  margin-bottom: 16px;
}
.u20-film-caption h3 { font-size: clamp(30px, 4.4vw, 52px); font-weight: 800; letter-spacing: -0.02em; line-height: 1.08; margin-bottom: 14px; text-shadow: 0 4px 40px rgba(0,0,0,0.5); }
.u20-film-caption p { font-size: 16.5px; line-height: 1.65; color: rgba(255, 255, 255, 0.78); max-width: 58ch; margin: 0 auto; }

/* ---------- Prizes ---------- */
.u20-prizes { background: var(--u20-surface); border-top: 1px solid var(--u20-line); border-bottom: 1px solid var(--u20-line); }
.u20-prizes-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 20px; margin-top: 56px; }
.u20-prize {
  display: flex;
  gap: 20px;
  align-items: flex-start;
  background: var(--u20-bg);
  border: 1px solid var(--u20-line);
  border-radius: 14px;
  padding: 28px;
}
.u20-prize-num {
  flex: 0 0 auto;
  font-size: 14px;
  font-weight: 700;
  color: var(--u20-red-bright);
  border: 1px solid rgba(240, 78, 54, 0.4);
  border-radius: 999px;
  width: 36px; height: 36px;
  display: flex; align-items: center; justify-content: center;
}
.u20-prize h3 { font-size: 17px; font-weight: 700; margin-bottom: 6px; }
.u20-prize p { font-size: 14px; line-height: 1.65; color: var(--u20-muted); }

/* ---------- Timeline ---------- */
.u20-timeline { margin-top: 64px; position: relative; padding-left: 36px; }
.u20-timeline::before {
  content: "";
  position: absolute;
  left: 8px; top: 6px; bottom: 6px;
  width: 2px;
  background: linear-gradient(180deg, var(--u20-red) 0%, rgba(215, 61, 40, 0.12) 100%);
}
.u20-phase { position: relative; padding-bottom: 48px; }
.u20-phase:last-child { padding-bottom: 0; }
.u20-phase::before {
  content: "";
  position: absolute;
  left: -36px; top: 6px;
  width: 18px; height: 18px;
  border-radius: 50%;
  background: var(--u20-bg);
  border: 2px solid var(--u20-red);
}
.u20-phase-label { font-size: 12.5px; font-weight: 600; letter-spacing: 0.18em; text-transform: uppercase; color: var(--u20-faint); margin-bottom: 6px; }
.u20-phase h3 { font-size: 21px; font-weight: 700; margin-bottom: 8px; }
.u20-phase p { font-size: 14.5px; line-height: 1.7; color: var(--u20-muted); max-width: 60ch; }

/* ---------- Judges ---------- */
.u20-judges-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 20px; margin-top: 56px; }
.u20-judge {
  aspect-ratio: 3 / 3.6;
  border-radius: 14px;
  border: 1px dashed rgba(255, 255, 255, 0.18);
  background: repeating-linear-gradient(-45deg, rgba(255,255,255,0.025) 0 10px, transparent 10px 20px);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 14px;
  color: var(--u20-faint);
  font-size: 13px;
  font-weight: 500;
}
.u20-judge svg { width: 34px; height: 34px; stroke: rgba(255, 255, 255, 0.25); }
.u20-judges-note { margin-top: 40px; font-size: 15px; color: var(--u20-muted); }
.u20-judges-note a { color: var(--u20-red-bright); font-weight: 600; }
.u20-judges-note a:hover { text-decoration: underline; }

/* ---------- Eligibility / FAQ ---------- */
.u20-faq-list { margin-top: 48px; border-top: 1px solid var(--u20-line); }
.u20-faq { border-bottom: 1px solid var(--u20-line); }
.u20-faq summary {
  cursor: pointer;
  list-style: none;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  padding: 26px 4px;
  font-size: 17px;
  font-weight: 600;
  transition: color 0.2s;
}
.u20-faq summary::-webkit-details-marker { display: none; }
.u20-faq summary:hover { color: var(--u20-red-bright); }
.u20-faq summary::after {
  content: "+";
  font-size: 24px;
  font-weight: 400;
  color: var(--u20-faint);
  transition: transform 0.25s ease;
  flex: 0 0 auto;
}
.u20-faq[open] summary::after { transform: rotate(45deg); }
.u20-faq-body { padding: 0 4px 26px; font-size: 15px; line-height: 1.75; color: var(--u20-muted); max-width: 70ch; }

/* ---------- Nomination form ---------- */
.u20-nominate { background: linear-gradient(180deg, var(--u20-bg) 0%, #191216 60%, #1c1013 100%); border-top: 1px solid var(--u20-line); }
.u20-form { margin-top: 56px; display: grid; grid-template-columns: 1fr 1fr; gap: 20px 20px; }
.u20-field { display: flex; flex-direction: column; gap: 8px; }
.u20-field.full { grid-column: 1 / -1; }
.u20-field label { font-size: 13.5px; font-weight: 600; color: var(--u20-text); }
.u20-field label .req { color: var(--u20-red-bright); }
.u20-field .hint { font-size: 12.5px; color: var(--u20-faint); font-weight: 400; }
.u20-field input,
.u20-field select,
.u20-field textarea {
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid var(--u20-line);
  border-radius: 8px;
  min-height: 48px;
  padding: 12px 16px;
  color: var(--u20-text);
  font-family: var(--zh-stack);
  font-size: 14.5px;
  transition: border-color 0.2s, background 0.2s;
}
.u20-field textarea { min-height: 140px; resize: vertical; line-height: 1.6; }
.u20-field input:focus, .u20-field select:focus, .u20-field textarea:focus {
  outline: none;
  border-color: var(--u20-red-bright);
  background: rgba(255, 255, 255, 0.08);
}
.u20-field input::placeholder, .u20-field textarea::placeholder { color: var(--u20-faint); }
.u20-field select { appearance: none; -webkit-appearance: none; background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='8' fill='none'%3E%3Cpath d='M1 1l5 5 5-5' stroke='rgba(255,255,255,0.5)' stroke-width='2'/%3E%3C/svg%3E"); background-repeat: no-repeat; background-position: right 16px center; padding-right: 40px; }
.u20-field select option { background: var(--u20-surface); color: var(--u20-text); }

.u20-consent {
  grid-column: 1 / -1;
  display: none;
  gap: 12px;
  align-items: flex-start;
  background: rgba(215, 61, 40, 0.08);
  border: 1px solid rgba(215, 61, 40, 0.35);
  border-radius: 10px;
  padding: 18px 20px;
  font-size: 14px;
  line-height: 1.6;
  color: var(--u20-text);
}
.u20-consent.visible { display: flex; }
.u20-consent input { margin-top: 3px; width: 18px; height: 18px; accent-color: var(--u20-red); flex: 0 0 auto; }

.u20-form-footer { grid-column: 1 / -1; display: flex; flex-direction: column; gap: 16px; margin-top: 8px; }
.u20-form-footer .u20-btn { align-self: flex-start; padding: 15px 44px; font-size: 15px; }
.u20-form-privacy { font-size: 12.5px; line-height: 1.65; color: var(--u20-faint); max-width: 72ch; }

/* ---------- Footer ---------- */
.u20-footer { border-top: 1px solid var(--u20-line); padding: 48px 0 56px; }
.u20-footer-inner { display: flex; align-items: center; justify-content: space-between; gap: 24px; flex-wrap: wrap; }
.u20-footer img { height: 30px; width: auto; opacity: 0.85; }
.u20-footer p { font-size: 13px; color: var(--u20-faint); line-height: 1.7; }
.u20-footer a { color: var(--u20-muted); }
.u20-footer a:hover { color: #fff; }

/* ---------- Responsive ---------- */
@media (max-width: 960px) {
  .u20-section { padding: 88px 0; }
  .u20-nav a.u20-nav-link { display: none; }
  .u20-mission-grid { grid-template-columns: 1fr; gap: 40px; }
  .u20-cats-grid { grid-template-columns: 1fr 1fr; }
  .u20-judges-grid { grid-template-columns: repeat(2, 1fr); }
  .u20-stats-grid { grid-template-columns: 1fr 1fr; }
  .u20-stat:nth-child(3) { border-left: none; }
  .u20-stat:nth-child(1), .u20-stat:nth-child(2) { border-bottom: 1px solid var(--u20-line); }
  .u20-prizes-grid { grid-template-columns: 1fr; }
  .u20-form { grid-template-columns: 1fr; }
}
@media (max-width: 620px) {
  .u20-cats-grid { grid-template-columns: 1fr; }
  .u20-header-logo span { display: none; }
  .u20-film { height: 280vh; }
}