:root {
  --bg: #ffffff;
  --surface: #f6f7f9;
  --surface-alt: #f0f2f5;
  --ink: #111827;
  --ink-secondary: #374151;
  --muted: #5d646e;
  --line: #e5e7eb;
  --line-strong: #d1d5db;
  --accent: #126abd;
  --accent-hover: #0e58a1;
  --accent-soft: #e8f2fc;
  --mint: #0f9f6e;
  --mint-soft: #ecfdf5;
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 18px;
  --shadow-sm: 0 1px 2px rgba(15, 23, 42, 0.05);
  --shadow-md: 0 12px 32px -8px rgba(15, 23, 42, 0.1), 0 2px 6px rgba(15, 23, 42, 0.04);
  --shadow-lg: 0 24px 56px -14px rgba(15, 23, 42, 0.16), 0 4px 12px rgba(15, 23, 42, 0.06);
  --font: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Noto Sans SC", "Microsoft YaHei", sans-serif;
  --max-w: 1120px;
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}

body {
  margin: 0;
  font-family: var(--font);
  font-size: 16px;
  line-height: 1.65;
  color: var(--ink);
  background: var(--bg);
  -webkit-font-smoothing: antialiased;
}

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

a {
  color: inherit;
}

button {
  font: inherit;
}

.container {
  width: 100%;
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 24px;
}

/* Header */
.site-header {
  position: sticky;
  top: 0;
  z-index: 40;
  background: rgba(255, 255, 255, 0.88);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--line);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  min-height: 64px;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  text-decoration: none;
  font-weight: 700;
  font-size: 18px;
  letter-spacing: -0.015em;
  flex-shrink: 0;
}

.brand img {
  width: 30px;
  height: 30px;
  border-radius: 7px;
  border: 1px solid var(--line);
}

.version-pill {
  font-size: 11px;
  font-weight: 600;
  color: var(--accent);
  background: var(--accent-soft);
  padding: 2px 7px;
  border-radius: 999px;
  letter-spacing: 0.01em;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 24px;
}

.nav-links a {
  text-decoration: none;
  font-size: 14px;
  font-weight: 500;
  color: var(--muted);
  transition: color 140ms ease;
}

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

.header-actions {
  display: flex;
  align-items: center;
  gap: 10px;
  flex-shrink: 0;
}

.lang-switch {
  display: inline-flex;
  align-items: center;
  padding: 2px;
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 999px;
}

.lang-btn {
  border: 0;
  background: transparent;
  color: var(--muted);
  font-size: 12px;
  font-weight: 600;
  padding: 5px 10px;
  border-radius: 999px;
  cursor: pointer;
  transition: background 140ms ease, color 140ms ease;
}

.lang-btn[aria-pressed="true"] {
  background: var(--bg);
  color: var(--ink);
  box-shadow: var(--shadow-sm);
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  text-decoration: none;
  font-weight: 600;
  border-radius: var(--radius-sm);
  border: 1px solid transparent;
  cursor: pointer;
  transition: background 150ms ease, border-color 150ms ease, transform 150ms ease, box-shadow 150ms ease;
  white-space: nowrap;
}

.btn-sm {
  font-size: 13px;
  padding: 8px 14px;
}

.btn-lg {
  font-size: 15px;
  padding: 12px 22px;
}

.btn-primary {
  background: var(--accent);
  color: #ffffff;
  box-shadow: 0 2px 8px rgba(18, 106, 189, 0.22);
}

.btn-primary:hover {
  background: var(--accent-hover);
  transform: translateY(-1px);
}

.btn-secondary {
  background: var(--bg);
  color: var(--ink);
  border-color: var(--line-strong);
}

.btn-secondary:hover {
  background: var(--surface);
  border-color: #b6bec9;
}

/* Hero */
.hero {
  padding: clamp(44px, 6vw, 76px) 0 clamp(40px, 5vw, 68px);
  background:
    radial-gradient(circle at 50% 0%, rgba(18, 106, 189, 0.055), transparent 56%),
    radial-gradient(#e2e7ee 1px, transparent 1px);
  background-size: 100% 100%, 20px 20px;
  border-bottom: 1px solid var(--line);
}

.hero-copy {
  max-width: 780px;
  margin: 0 auto;
  text-align: center;
}

.hero-eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-size: 13px;
  font-weight: 600;
  color: var(--ink-secondary);
  background: rgba(255, 255, 255, 0.92);
  border: 1px solid var(--line);
  padding: 5px 13px;
  border-radius: 999px;
  margin-bottom: 20px;
  box-shadow: var(--shadow-sm);
}

.status-dot {
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: var(--mint);
  flex-shrink: 0;
}

.hero h1 {
  margin: 0 0 18px;
  font-size: clamp(30px, 4.4vw, 48px);
  line-height: 1.18;
  letter-spacing: -0.025em;
  color: var(--ink);
}

.hero-sub {
  margin: 0 auto 28px;
  max-width: 660px;
  font-size: clamp(16px, 1.8vw, 18px);
  line-height: 1.7;
  color: var(--muted);
}

.hero-cta {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 12px;
  margin-bottom: 18px;
}

.hero-meta {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 8px 18px;
  font-size: 13px;
  color: var(--muted);
}

.hero-meta span {
  display: inline-flex;
  align-items: center;
  gap: 6px;
}

.hero-frame {
  margin: clamp(32px, 4vw, 48px) auto 0;
  max-width: 980px;
  background: var(--bg);
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-lg);
  overflow: hidden;
}

.frame-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 10px 16px;
  background: var(--surface);
  border-bottom: 1px solid var(--line);
  font-size: 12px;
  color: var(--muted);
}

.frame-dots {
  display: inline-flex;
  gap: 6px;
}

.frame-dots i {
  display: block;
  width: 9px;
  height: 9px;
  border-radius: 50%;
  background: #d1d5db;
}

.hero-frame img {
  width: 100%;
  aspect-ratio: 16 / 10;
  object-fit: cover;
}

/* Sections */
.section {
  padding: clamp(56px, 7vw, 88px) 0;
}

.section-muted {
  background: var(--surface);
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
}

.section-head {
  max-width: 680px;
  margin: 0 auto clamp(32px, 4vw, 44px);
  text-align: center;
}

.section-kicker {
  margin: 0 0 8px;
  font-size: 12px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--accent);
}

.section-head h2 {
  margin: 0 0 12px;
  font-size: clamp(24px, 3vw, 34px);
  line-height: 1.24;
  letter-spacing: -0.02em;
}

.section-head p {
  margin: 0;
  color: var(--muted);
  font-size: 16px;
}

/* Preview Gallery */
.gallery-tabs {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 8px;
  margin-bottom: 24px;
}

.gallery-tab {
  border: 1px solid var(--line);
  background: var(--bg);
  color: var(--ink-secondary);
  padding: 9px 15px;
  border-radius: 999px;
  font-size: 13px;
  font-weight: 600;
  cursor: pointer;
  transition: all 140ms ease;
}

.gallery-tab:hover {
  border-color: var(--line-strong);
  color: var(--ink);
}

.gallery-tab[aria-selected="true"] {
  background: var(--ink);
  border-color: var(--ink);
  color: #ffffff;
}

.gallery-stage {
  max-width: 980px;
  margin: 0 auto;
  background: var(--bg);
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-md);
  overflow: hidden;
}

.gallery-stage img {
  width: 100%;
  aspect-ratio: 16 / 10;
  object-fit: cover;
  background: var(--surface);
}

.gallery-caption {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 10px 16px;
  padding: 16px 22px;
  border-top: 1px solid var(--line);
  background: var(--bg);
}

.gallery-caption strong {
  font-size: 15px;
  color: var(--ink);
}

.gallery-caption span {
  font-size: 14px;
  color: var(--muted);
}

/* Features Grid */
.features-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 18px;
}

.feature-card {
  background: var(--bg);
  border: 1px solid var(--line);
  border-radius: var(--radius-md);
  padding: 24px;
  box-shadow: var(--shadow-sm);
}

.feature-index {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  font-size: 12px;
  font-weight: 700;
  color: var(--accent);
  background: var(--accent-soft);
  padding: 3px 9px;
  border-radius: 6px;
  margin-bottom: 14px;
  font-variant-numeric: tabular-nums;
}

.feature-card h3 {
  margin: 0 0 8px;
  font-size: 17px;
  line-height: 1.35;
}

.feature-card p {
  margin: 0;
  font-size: 14px;
  line-height: 1.65;
  color: var(--muted);
}

/* Steps */
.steps-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 18px;
}

.step-card {
  background: var(--bg);
  border: 1px solid var(--line);
  border-radius: var(--radius-md);
  padding: 24px;
}

.step-num {
  width: 32px;
  height: 32px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border-radius: 999px;
  background: var(--ink);
  color: #ffffff;
  font-size: 14px;
  font-weight: 700;
  margin-bottom: 14px;
}

.step-card h3 {
  margin: 0 0 8px;
  font-size: 17px;
}

.step-card p {
  margin: 0;
  font-size: 14px;
  color: var(--muted);
}

/* Specs & Privacy */
.specs-layout {
  display: grid;
  grid-template-columns: 1.1fr 0.9fr;
  gap: 24px;
  align-items: stretch;
}

.spec-panel {
  background: var(--bg);
  border: 1px solid var(--line);
  border-radius: var(--radius-md);
  padding: 28px;
  box-shadow: var(--shadow-sm);
}

.spec-panel h3 {
  margin: 0 0 14px;
  font-size: 19px;
}

.spec-list {
  margin: 0;
  padding: 0;
  list-style: none;
  display: grid;
  gap: 12px;
}

.spec-list li {
  display: flex;
  gap: 10px;
  font-size: 14px;
  color: var(--ink-secondary);
}

.spec-check {
  color: var(--mint);
  font-weight: 700;
  flex-shrink: 0;
}

.meta-table {
  display: grid;
  gap: 12px;
}

.meta-row {
  display: flex;
  justify-content: space-between;
  gap: 16px;
  padding-bottom: 12px;
  border-bottom: 1px solid var(--line);
  font-size: 14px;
}

.meta-row:last-child {
  border-bottom: 0;
  padding-bottom: 0;
}

.meta-row dt {
  color: var(--muted);
  font-weight: 500;
}

.meta-row dd {
  margin: 0;
  color: var(--ink);
  font-weight: 600;
  text-align: right;
}

/* FAQ */
.faq-list {
  max-width: 780px;
  margin: 0 auto;
  display: grid;
  gap: 12px;
}

.faq-item {
  background: var(--bg);
  border: 1px solid var(--line);
  border-radius: var(--radius-md);
  padding: 20px 24px;
}

.faq-item h3 {
  margin: 0 0 8px;
  font-size: 16px;
  line-height: 1.4;
}

.faq-item p {
  margin: 0;
  font-size: 14px;
  color: var(--muted);
}

/* Bottom CTA */
.cta-box {
  background: var(--ink);
  color: #ffffff;
  border-radius: var(--radius-lg);
  padding: clamp(32px, 5vw, 52px);
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
}

.cta-box h2 {
  margin: 0 0 8px;
  font-size: clamp(22px, 2.8vw, 30px);
  line-height: 1.25;
}

.cta-box p {
  margin: 0;
  color: #cbd5e1;
  font-size: 15px;
  max-width: 560px;
}

.cta-box .btn-primary {
  background: #ffffff;
  color: var(--ink);
  box-shadow: none;
}

.cta-box .btn-primary:hover {
  background: #f1f5f9;
}

/* Footer */
.site-footer {
  border-top: 1px solid var(--line);
  padding: 32px 0 44px;
  font-size: 13px;
  color: var(--muted);
}

.footer-inner {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
}

.footer-links {
  display: flex;
  flex-wrap: wrap;
  gap: 18px;
}

.footer-links a {
  text-decoration: none;
  color: var(--ink-secondary);
}

.footer-links a:hover {
  color: var(--accent);
  text-decoration: underline;
}

@media (max-width: 900px) {
  .nav-links {
    display: none;
  }
  .features-grid,
  .steps-grid,
  .specs-layout {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 560px) {
  .container {
    padding: 0 16px;
  }
  .header-inner {
    min-height: 58px;
  }
  .btn-sm.header-cta {
    display: none;
  }
  .meta-row {
    flex-direction: column;
    gap: 4px;
  }
  .meta-row dd {
    text-align: left;
  }
}