:root {
  --bg-0: #121820;
  --bg-1: #1a2230;
  --bg-2: #243041;
  --text: #f4f6fa;
  --text-muted: #9aa8ba;
  --accent: #78beff;
  --accent-strong: #4f9de8;
  --line: rgba(255, 255, 255, 0.09);
  --card: rgba(255, 255, 255, 0.05);
  --card-hover: rgba(255, 255, 255, 0.08);
  --glow: rgba(120, 190, 255, 0.16);
  --radius: 22px;
  --max: 1160px;
  --nav-h: 72px;
  --phone-w: 280px;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "SF Pro Text", "Segoe UI", Roboto, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  background: var(--bg-0);
  color: var(--text);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

body::before {
  content: "";
  position: fixed;
  inset: 0;
  pointer-events: none;
  background:
    radial-gradient(ellipse 70% 45% at 10% -5%, var(--glow), transparent 55%),
    radial-gradient(ellipse 50% 35% at 95% 5%, rgba(120, 160, 255, 0.1), transparent 50%),
    linear-gradient(180deg, var(--bg-1) 0%, var(--bg-0) 50%, #0e131a 100%);
  z-index: -1;
}

a { color: inherit; text-decoration: none; }
img { display: block; max-width: 100%; }

.container {
  width: min(var(--max), calc(100% - 40px));
  margin: 0 auto;
}

/* ── i18n: hide all, show active only ── */
[data-i18n] { display: none !important; }

html[data-lang="zh"] [data-i18n="zh"],
html[data-lang="zh-Hant"] [data-i18n="zh-Hant"],
html[data-lang="en"] [data-i18n="en"],
html[data-lang="ja"] [data-i18n="ja"],
html[data-lang="ko"] [data-i18n="ko"] {
  display: block !important;
}

html[data-lang="zh"] .btn [data-i18n="zh"],
html[data-lang="zh-Hant"] .btn [data-i18n="zh-Hant"],
html[data-lang="en"] .btn [data-i18n="en"],
html[data-lang="ja"] .btn [data-i18n="ja"],
html[data-lang="ko"] .btn [data-i18n="ko"],
html[data-lang="zh"] .eyebrow [data-i18n="zh"],
html[data-lang="zh-Hant"] .eyebrow [data-i18n="zh-Hant"],
html[data-lang="en"] .eyebrow [data-i18n="en"],
html[data-lang="ja"] .eyebrow [data-i18n="ja"],
html[data-lang="ko"] .eyebrow [data-i18n="ko"],
html[data-lang="zh"] .nav-links [data-i18n="zh"],
html[data-lang="zh-Hant"] .nav-links [data-i18n="zh-Hant"],
html[data-lang="en"] .nav-links [data-i18n="en"],
html[data-lang="ja"] .nav-links [data-i18n="ja"],
html[data-lang="ko"] .nav-links [data-i18n="ko"],
html[data-lang="zh"] .footer-links [data-i18n="zh"],
html[data-lang="zh-Hant"] .footer-links [data-i18n="zh-Hant"],
html[data-lang="en"] .footer-links [data-i18n="en"],
html[data-lang="ja"] .footer-links [data-i18n="ja"],
html[data-lang="ko"] .footer-links [data-i18n="ko"] {
  display: inline !important;
}

html[data-lang="zh"] .hero-points [data-i18n="zh"],
html[data-lang="zh-Hant"] .hero-points [data-i18n="zh-Hant"],
html[data-lang="en"] .hero-points [data-i18n="en"],
html[data-lang="ja"] .hero-points [data-i18n="ja"],
html[data-lang="ko"] .hero-points [data-i18n="ko"] {
  display: flex !important;
  align-items: center;
  gap: 10px;
}

body.lang-switching [data-i18n] {
  animation: i18nSwap 0.32s ease both;
}

@keyframes i18nSwap {
  from { opacity: 0; transform: translateY(6px); }
  to   { opacity: 1; transform: translateY(0); }
}

/* ── Motion ── */
@keyframes fadeUp {
  from { opacity: 0; transform: translateY(28px); }
  to   { opacity: 1; transform: translateY(0); }
}

@keyframes floatPhone {
  0%, 100% { transform: translateY(0) rotate(0deg); }
  50%      { transform: translateY(-14px) rotate(0.6deg); }
}

@keyframes glowPulse {
  0%, 100% { opacity: 0.55; transform: scale(1); }
  50%      { opacity: 0.9; transform: scale(1.06); }
}

.hero-copy > * {
  animation: fadeUp 0.75s cubic-bezier(0.22, 1, 0.36, 1) both;
}
.hero-copy > *:nth-child(1) { animation-delay: 0.05s; }
.hero-copy > *:nth-child(2) { animation-delay: 0.12s; }
.hero-copy > *:nth-child(3) { animation-delay: 0.19s; }
.hero-copy > *:nth-child(4) { animation-delay: 0.26s; }
.hero-copy > *:nth-child(5) { animation-delay: 0.33s; }

.hero-phone-wrap .phone {
  animation: floatPhone 7s ease-in-out infinite;
}

.hero-phone-wrap .phone-glow {
  animation: glowPulse 5s ease-in-out infinite;
}

.reveal {
  opacity: 0;
  transform: translateY(32px);
  transition: opacity 0.7s cubic-bezier(0.22, 1, 0.36, 1),
              transform 0.7s cubic-bezier(0.22, 1, 0.36, 1);
}

.reveal.is-visible {
  opacity: 1;
  transform: translateY(0);
}

.reveal-delay-2 { transition-delay: 0.15s; }

.card.reveal:nth-child(2) { transition-delay: 0.06s; }
.card.reveal:nth-child(3) { transition-delay: 0.12s; }
.card.reveal:nth-child(4) { transition-delay: 0.18s; }
.card.reveal:nth-child(5) { transition-delay: 0.24s; }
.card.reveal:nth-child(6) { transition-delay: 0.30s; }

.phone-screen {
  transition: opacity 0.45s ease, transform 0.45s cubic-bezier(0.22, 1, 0.36, 1);
}

.phone-screen.is-changing {
  opacity: 0 !important;
  transform: scale(0.96);
}

.stat {
  transition: transform 0.25s ease, border-color 0.25s ease;
}

.stat:hover {
  transform: translateY(-3px);
  border-color: rgba(120, 190, 255, 0.2);
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
  .reveal { opacity: 1; transform: none; }
}

/* Nav */
.nav {
  position: sticky;
  top: 0;
  z-index: 30;
  height: var(--nav-h);
  backdrop-filter: blur(20px);
  background: rgba(18, 24, 32, 0.78);
  border-bottom: 1px solid transparent;
  transition: border-color 0.3s ease, background 0.3s ease, box-shadow 0.3s ease;
}

.nav.nav-scrolled {
  border-bottom-color: var(--line);
  background: rgba(18, 24, 32, 0.92);
  box-shadow: 0 8px 32px rgba(0, 0, 0, 0.25);
}

.nav-inner {
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
}

.brand {
  display: flex;
  align-items: center;
  gap: 12px;
  font-weight: 700;
  letter-spacing: -0.02em;
}

.brand img {
  width: 36px;
  height: 36px;
  border-radius: 9px;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 28px;
  color: var(--text-muted);
  font-size: 14px;
}

.nav-links a:hover { color: var(--text); }

.nav-actions {
  display: flex;
  align-items: center;
  gap: 12px;
}

.lang-select {
  appearance: none;
  border: 1px solid var(--line);
  background: rgba(255, 255, 255, 0.04) url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='8' viewBox='0 0 12 8'%3E%3Cpath fill='%239aa8ba' d='M1 1.5 6 6.5 11 1.5'/%3E%3C/svg%3E") no-repeat right 12px center;
  color: var(--text-muted);
  border-radius: 999px;
  padding: 8px 34px 8px 14px;
  font-size: 13px;
  cursor: pointer;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  border-radius: 999px;
  padding: 12px 20px;
  font-size: 15px;
  font-weight: 600;
  transition: transform 0.2s ease, box-shadow 0.2s ease;
  white-space: nowrap;
}

.btn:hover { transform: translateY(-1px); }

.btn-primary {
  background: linear-gradient(135deg, var(--accent), var(--accent-strong));
  color: #0d1520;
  box-shadow: 0 10px 30px rgba(79, 157, 232, 0.28);
}

.btn-secondary {
  border: 1px solid var(--line);
  background: rgba(255, 255, 255, 0.04);
  color: var(--text);
}

/* Hero */
.hero {
  padding: 64px 0 32px;
  overflow: hidden;
}

.hero-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 40px;
  align-items: center;
}

.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 6px 12px;
  border-radius: 999px;
  border: 1px solid var(--line);
  background: rgba(255, 255, 255, 0.04);
  color: var(--accent);
  font-size: 13px;
  font-weight: 600;
  margin-bottom: 18px;
}

h1 {
  margin: 0 0 16px;
  font-size: clamp(38px, 5.5vw, 60px);
  line-height: 1.06;
  letter-spacing: -0.04em;
}

.lead {
  margin: 0 0 28px;
  max-width: 520px;
  color: var(--text-muted);
  font-size: 18px;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-bottom: 28px;
}

.hero-points {
  display: grid;
  gap: 10px;
  color: var(--text-muted);
  font-size: 14px;
}

.hero-points [data-i18n]::before {
  content: "";
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--accent);
  flex-shrink: 0;
}

/* Phone mockup */
.phone-stage {
  position: relative;
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 580px;
}

.phone-glow {
  position: absolute;
  width: 360px;
  height: 360px;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(120, 190, 255, 0.2), transparent 70%);
  filter: blur(12px);
}

.phone {
  position: relative;
  width: min(var(--phone-w), 74vw);
  aspect-ratio: 1179 / 2556;
  border-radius: 44px;
  padding: 10px;
  background: linear-gradient(155deg, #556275, #1a2230 55%, #0f141c);
  box-shadow:
    0 40px 100px rgba(0, 0, 0, 0.5),
    inset 0 0 0 1px rgba(255, 255, 255, 0.14);
}

.phone::before {
  content: "";
  position: absolute;
  top: 14px;
  left: 50%;
  transform: translateX(-50%);
  width: 28%;
  height: 26px;
  border-radius: 20px;
  background: #0a0e14;
  z-index: 2;
}

.phone-screen {
  width: 100%;
  height: 100%;
  border-radius: 36px;
  overflow: hidden;
  object-fit: cover;
  object-position: top;
  background: #000;
}

/* phone-screen transition defined in motion section above */

.phone-shadow {
  position: absolute;
  bottom: -20px;
  width: 70%;
  height: 30px;
  background: radial-gradient(ellipse, rgba(0, 0, 0, 0.45), transparent 70%);
  filter: blur(8px);
}

/* Stats strip */
.stats {
  padding: 28px 0 8px;
}

.stats-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 14px;
}

.stat {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: 16px;
  padding: 18px 20px;
  text-align: center;
}

.stat strong {
  display: block;
  font-size: 22px;
  letter-spacing: -0.02em;
  margin-bottom: 4px;
}

.stat span {
  color: var(--text-muted);
  font-size: 13px;
}

/* Showcase */
.showcase {
  padding: 72px 0 96px;
}

.showcase-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 48px;
  align-items: center;
}

.feature-tabs {
  display: grid;
  gap: 10px;
}

.feature-tab {
  display: grid;
  grid-template-columns: 48px 1fr;
  gap: 14px;
  align-items: start;
  padding: 18px 20px;
  border-radius: 18px;
  border: 1px solid transparent;
  background: transparent;
  color: inherit;
  text-align: left;
  cursor: pointer;
  transition: background 0.25s ease, border-color 0.25s ease,
              box-shadow 0.25s ease, transform 0.25s ease;
  font: inherit;
}

.feature-tab:hover {
  background: var(--card);
}

.feature-tab.is-active {
  background: var(--card-hover);
  border-color: rgba(120, 190, 255, 0.25);
  box-shadow: inset 3px 0 0 var(--accent);
  transform: translateX(4px);
}

.feature-tab-num {
  width: 48px;
  height: 48px;
  border-radius: 14px;
  display: grid;
  place-items: center;
  background: rgba(120, 190, 255, 0.1);
  color: var(--accent);
  font-size: 14px;
  font-weight: 700;
}

.feature-tab h3 {
  margin: 0 0 4px;
  font-size: 17px;
}

.feature-tab p {
  margin: 0;
  color: var(--text-muted);
  font-size: 14px;
  line-height: 1.5;
}

.showcase-phone-wrap {
  position: relative;
  display: flex;
  flex-direction: column;
  align-items: center;
}

.showcase-dots {
  display: flex;
  gap: 8px;
  margin-top: 20px;
}

.showcase-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  border: none;
  padding: 0;
  background: rgba(255, 255, 255, 0.2);
  cursor: pointer;
  transition: transform 0.2s ease, background 0.2s ease;
}

.showcase-dot.is-active {
  background: var(--accent);
  transform: scale(1.2);
}

/* Tutorial video */
.tutorial {
  padding: 0 0 80px;
}

.video-shell {
  max-width: 880px;
  margin: 0 auto 28px;
}

.video-frame {
  position: relative;
  aspect-ratio: 16 / 9;
  border-radius: 24px;
  overflow: hidden;
  border: 1px solid var(--line);
  background: var(--card);
  box-shadow: 0 24px 80px rgba(0, 0, 0, 0.35);
  transition: opacity 0.3s ease, transform 0.3s ease;
}

.video-frame iframe,
.video-frame video {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  border: 0;
  background: #000;
}

.video-placeholder {
  position: absolute;
  inset: 0;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 16px;
  padding: 24px;
  text-align: center;
  border: none;
  cursor: default;
  color: inherit;
  font: inherit;
  background:
    linear-gradient(180deg, rgba(18, 24, 32, 0.2), rgba(18, 24, 32, 0.75)),
    var(--poster, #1a2230) center / cover no-repeat;
}

.video-placeholder.is-ready {
  cursor: pointer;
}

.video-placeholder.is-ready:hover .video-play-btn {
  transform: scale(1.06);
  box-shadow: 0 12px 40px rgba(120, 190, 255, 0.35);
}

.video-play-btn {
  width: 72px;
  height: 72px;
  border-radius: 50%;
  display: grid;
  place-items: center;
  background: rgba(255, 255, 255, 0.95);
  color: #0d1520;
  box-shadow: 0 8px 32px rgba(0, 0, 0, 0.3);
  transition: transform 0.25s ease, box-shadow 0.25s ease;
}

.video-play-btn svg {
  width: 28px;
  height: 28px;
  margin-left: 4px;
}

.video-placeholder-label {
  font-size: 15px;
  font-weight: 600;
  color: var(--text);
  text-shadow: 0 1px 8px rgba(0, 0, 0, 0.5);
}

.video-placeholder-hint {
  font-size: 13px;
  color: var(--text-muted);
  max-width: 320px;
  text-shadow: 0 1px 6px rgba(0, 0, 0, 0.4);
}

.tutorial-menu {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 14px;
  max-width: 880px;
  margin: 0 auto;
}

.tutorial-menu-item {
  display: flex;
  gap: 14px;
  align-items: flex-start;
  padding: 18px;
  border-radius: 16px;
  border: 1px solid var(--line);
  background: var(--card);
  color: inherit;
  text-align: left;
  cursor: pointer;
  font: inherit;
  transition: background 0.25s ease, border-color 0.25s ease,
              box-shadow 0.25s ease, transform 0.25s ease;
}

.tutorial-menu-item:hover {
  background: var(--card-hover);
}

.tutorial-menu-item.is-active {
  background: var(--card-hover);
  border-color: rgba(120, 190, 255, 0.3);
  box-shadow: inset 3px 0 0 var(--accent);
  transform: translateX(3px);
}

.tutorial-menu-num {
  flex-shrink: 0;
  width: 36px;
  height: 36px;
  border-radius: 10px;
  display: grid;
  place-items: center;
  font-size: 13px;
  font-weight: 700;
  color: var(--accent);
  background: rgba(120, 190, 255, 0.1);
}

.tutorial-menu-item.is-active .tutorial-menu-num {
  background: rgba(120, 190, 255, 0.2);
}

.tutorial-menu-title {
  display: block;
  font-size: 15px;
  font-weight: 600;
  margin-bottom: 4px;
}

.tutorial-menu-subtitle {
  display: block;
  font-size: 13px;
  color: var(--text-muted);
  line-height: 1.45;
}

.video-frame.is-switching {
  opacity: 0.55;
  transform: scale(0.985);
}

.tutorial-fallback {
  text-align: center;
  margin: 24px 0 0;
  font-size: 14px;
  color: var(--text-muted);
}

.tutorial-fallback a {
  color: var(--accent);
  text-decoration: underline;
  text-underline-offset: 3px;
}

html[data-lang="zh"] .tutorial-fallback [data-i18n="zh"],
html[data-lang="zh-Hant"] .tutorial-fallback [data-i18n="zh-Hant"],
html[data-lang="en"] .tutorial-fallback [data-i18n="en"],
html[data-lang="ja"] .tutorial-fallback [data-i18n="ja"],
html[data-lang="ko"] .tutorial-fallback [data-i18n="ko"] {
  display: inline !important;
}

/* Sections */
.section { padding: 72px 0; }

.section-head {
  max-width: 640px;
  margin-bottom: 36px;
}

.section-head h2 {
  margin: 0 0 10px;
  font-size: clamp(28px, 4vw, 40px);
  letter-spacing: -0.03em;
}

.section-head p {
  margin: 0;
  color: var(--text-muted);
  font-size: 17px;
}

.feature-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 18px;
}

.card {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 24px;
  transition: background 0.2s ease, transform 0.2s ease;
}

.card:hover {
  background: var(--card-hover);
  transform: translateY(-2px);
}

.card-icon {
  width: 42px;
  height: 42px;
  border-radius: 12px;
  display: grid;
  place-items: center;
  margin-bottom: 16px;
  background: rgba(120, 190, 255, 0.1);
  color: var(--accent);
  font-size: 18px;
}

.card h3 { margin: 0 0 8px; font-size: 18px; }
.card p { margin: 0; color: var(--text-muted); font-size: 15px; }

.compat {
  display: grid;
  grid-template-columns: 1.1fr 0.9fr;
  gap: 24px;
}

.compat-box,
.steps-box {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 28px;
}

.compat-list,
.steps-list {
  margin: 0;
  padding: 0;
  list-style: none;
  display: grid;
  gap: 14px;
}

.compat-list li,
.steps-list li {
  display: flex;
  gap: 12px;
  color: var(--text-muted);
}

.compat-list strong,
.steps-list strong {
  color: var(--text);
  display: block;
  margin-bottom: 4px;
}

.badge {
  display: inline-flex;
  padding: 4px 10px;
  border-radius: 999px;
  background: rgba(120, 190, 255, 0.1);
  color: var(--accent);
  font-size: 12px;
  font-weight: 600;
}

.note {
  margin-top: 18px;
  padding: 14px 16px;
  border-radius: 14px;
  background: rgba(255, 255, 255, 0.03);
  border: 1px solid var(--line);
  color: var(--text-muted);
  font-size: 14px;
}

.cta { padding: 56px 0 80px; }

.cta-panel {
  border-radius: 28px;
  padding: 48px 40px;
  text-align: center;
  background:
    linear-gradient(135deg, rgba(120, 190, 255, 0.12), rgba(255, 255, 255, 0.02)),
    var(--card);
  border: 1px solid var(--line);
}

.cta-panel h2 {
  margin: 0 0 12px;
  font-size: clamp(28px, 4vw, 40px);
}

.cta-panel p {
  margin: 0 auto 24px;
  max-width: 560px;
  color: var(--text-muted);
}

.footer {
  border-top: 1px solid var(--line);
  padding: 28px 0 40px;
  color: var(--text-muted);
  font-size: 14px;
}

.footer-grid {
  display: flex;
  justify-content: space-between;
  gap: 20px;
  flex-wrap: wrap;
}

.footer-links {
  display: flex;
  gap: 20px;
  flex-wrap: wrap;
}

@media (max-width: 960px) {
  .hero-grid,
  .showcase-grid,
  .feature-grid,
  .compat,
  .stats-grid {
    grid-template-columns: 1fr;
  }

  .nav-links { display: none; }

  .phone-stage { min-height: 480px; }

  .feature-grid { grid-template-columns: 1fr 1fr; }

  .showcase-grid { gap: 32px; }

  .tutorial-menu { grid-template-columns: 1fr; }
}

@media (max-width: 640px) {
  .feature-grid { grid-template-columns: 1fr; }
  .hero { padding-top: 40px; }
  .cta-panel { padding: 28px 20px; }
  .stats-grid { grid-template-columns: 1fr 1fr; }
}