:root {
  --canvas: #09090b;
  --surface: #121215;
  --surface-elevated: #18181b;
  --surface-subtle: #16161a;
  --surface-hover: #1f1f24;
  --border: #27272a;
  --border-highlight: #3f3f46;
  --accent: #6366f1;
  --accent-hover: #4f46e5;
  --accent-muted: rgba(99, 102, 241, 0.15);
  --positive: #10b981;
  --positive-muted: rgba(16, 185, 129, 0.12);
  --text-primary: #ffffff;
  --text-secondary: #a1a1aa;
  --text-muted: #71717a;
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, monospace;
}

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  color-scheme: dark;
  background-color: var(--canvas);
  color: var(--text-primary);
  font-family: var(--font-sans);
  scroll-behavior: smooth;
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
}

body {
  background-color: var(--canvas);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  overflow-x: hidden;
}

/* Background Ambient Lighting */
.ambient-glow {
  position: fixed;
  top: -200px;
  left: 50%;
  transform: translateX(-50%);
  width: 900px;
  height: 500px;
  background: radial-gradient(circle, rgba(99, 102, 241, 0.18) 0%, rgba(16, 185, 129, 0.08) 45%, transparent 70%);
  pointer-events: none;
  z-index: 0;
}

.container {
  width: 100%;
  max-width: 1120px;
  margin: 0 auto;
  padding: 0 24px;
  position: relative;
  z-index: 1;
}

/* Navigation Header */
.navbar {
  position: sticky;
  top: 0;
  width: 100%;
  background: rgba(9, 9, 11, 0.85);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--border);
  z-index: 100;
}

.nav-container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 72px;
}

.brand {
  display: flex;
  align-items: center;
  gap: 14px;
  text-decoration: none;
  color: var(--text-primary);
}

.brand-logo {
  width: 38px;
  height: 38px;
  border-radius: 10px;
  object-fit: contain;
  filter: drop-shadow(0 4px 12px rgba(99, 102, 241, 0.35));
}

.brand-text {
  display: flex;
  flex-direction: column;
}

.brand-title {
  font-size: 1.15rem;
  font-weight: 800;
  letter-spacing: 0.5px;
}

.brand-subtitle {
  font-size: 0.72rem;
  font-weight: 600;
  color: var(--positive);
  letter-spacing: 1px;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 28px;
  list-style: none;
}

.nav-link {
  color: var(--text-secondary);
  text-decoration: none;
  font-size: 0.95rem;
  font-weight: 500;
  transition: color 0.2s;
}

.nav-link:hover {
  color: var(--text-primary);
}

.nav-cta {
  background: var(--accent);
  color: #fff;
  padding: 8px 18px;
  border-radius: 8px;
  font-size: 0.9rem;
  font-weight: 600;
  text-decoration: none;
  transition: background 0.2s, transform 0.15s;
}

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

/* Hero Section */
.hero {
  padding: 80px 0 50px;
  text-align: center;
}

.badge {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 6px 14px;
  border-radius: 9999px;
  background: var(--surface-elevated);
  border: 1px solid var(--border-highlight);
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--text-secondary);
  margin-bottom: 24px;
}

.badge-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--positive);
  box-shadow: 0 0 10px var(--positive);
}

.hero-title {
  font-size: clamp(2.4rem, 5vw, 3.8rem);
  font-weight: 800;
  letter-spacing: -0.03em;
  line-height: 1.15;
  margin-bottom: 20px;
}

.hero-gradient {
  background: linear-gradient(135deg, #ffffff 40%, #a5b4fc 75%, #34d399 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.hero-subtitle {
  font-size: 1.2rem;
  color: var(--text-secondary);
  max-width: 680px;
  margin: 0 auto 40px;
  font-weight: 400;
}

/* Download Section (Dual Cards) */
.download-hub {
  padding: 20px 0 70px;
}

.section-header {
  text-align: center;
  margin-bottom: 48px;
}

.section-title {
  font-size: 2rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  margin-bottom: 12px;
}

.section-desc {
  color: var(--text-secondary);
  font-size: 1.05rem;
}

.download-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(330px, 1fr));
  gap: 28px;
  margin-bottom: 40px;
}

.download-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 20px;
  padding: 36px;
  display: flex;
  flex-direction: column;
  position: relative;
  transition: transform 0.2s, border-color 0.2s, box-shadow 0.2s;
}

.download-card:hover {
  transform: translateY(-4px);
  border-color: var(--border-highlight);
  box-shadow: 0 20px 40px rgba(0, 0, 0, 0.45);
}

.download-card.primary {
  border-color: rgba(99, 102, 241, 0.4);
  background: linear-gradient(180deg, rgba(99, 102, 241, 0.05) 0%, var(--surface) 100%);
}

.card-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 24px;
}

.platform-icon {
  width: 52px;
  height: 52px;
  border-radius: 14px;
  background: var(--surface-elevated);
  border: 1px solid var(--border);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--accent);
}

.card-tag {
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.5px;
  padding: 4px 10px;
  border-radius: 6px;
  background: var(--positive-muted);
  color: var(--positive);
  border: 1px solid rgba(16, 185, 129, 0.25);
}

.platform-title {
  font-size: 1.5rem;
  font-weight: 700;
  margin-bottom: 8px;
}

.platform-desc {
  color: var(--text-secondary);
  font-size: 0.95rem;
  margin-bottom: 24px;
  flex-grow: 1;
}

.meta-list {
  list-style: none;
  margin-bottom: 28px;
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.meta-item {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 0.88rem;
  color: var(--text-secondary);
}

.meta-item svg {
  width: 16px;
  height: 16px;
  fill: var(--positive);
  flex-shrink: 0;
}

.btn-download {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 12px;
  padding: 16px 24px;
  border-radius: 12px;
  text-decoration: none;
  font-weight: 700;
  font-size: 1.05rem;
  transition: all 0.2s;
  background: var(--accent);
  color: #fff;
  border: none;
  cursor: pointer;
  box-shadow: 0 4px 16px rgba(99, 102, 241, 0.35);
}

.btn-download:hover {
  background: var(--accent-hover);
  transform: translateY(-2px);
  box-shadow: 0 8px 24px rgba(99, 102, 241, 0.45);
}

.btn-download.android {
  background: #0ea5e9;
  box-shadow: 0 4px 16px rgba(14, 165, 233, 0.3);
}

.btn-download.android:hover {
  background: #0284c7;
  box-shadow: 0 8px 24px rgba(14, 165, 233, 0.4);
}

.file-info {
  margin-top: 14px;
  font-size: 0.8rem;
  color: var(--text-muted);
  text-align: center;
  font-family: var(--font-mono);
}

/* QR Code Section for Android */
.qr-container {
  margin-top: 24px;
  padding-top: 20px;
  border-top: 1px dashed var(--border);
  display: flex;
  align-items: center;
  gap: 18px;
}

.qr-box {
  width: 96px;
  height: 96px;
  background: #ffffff;
  padding: 6px;
  border-radius: 10px;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}

.qr-box img, .qr-box svg {
  width: 100%;
  height: 100%;
  object-fit: contain;
}

.qr-text {
  font-size: 0.85rem;
  color: var(--text-secondary);
  line-height: 1.4;
}

.qr-text strong {
  color: var(--text-primary);
  display: block;
  margin-bottom: 4px;
}

/* Features Section */
.features {
  padding: 70px 0;
  border-top: 1px solid var(--border);
}

.features-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 24px;
}

.feature-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: 28px;
  transition: border-color 0.2s, transform 0.2s;
}

.feature-card:hover {
  border-color: var(--border-highlight);
  transform: translateY(-2px);
}

.feature-icon {
  width: 44px;
  height: 44px;
  border-radius: 10px;
  background: var(--surface-elevated);
  border: 1px solid var(--border);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 20px;
  color: var(--accent);
}

.feature-icon.emerald {
  color: var(--positive);
}

.feature-title {
  font-size: 1.2rem;
  font-weight: 700;
  margin-bottom: 10px;
}

.feature-desc {
  color: var(--text-secondary);
  font-size: 0.95rem;
  line-height: 1.55;
}

/* Installation Guide */
.guide {
  padding: 70px 0;
  border-top: 1px solid var(--border);
}

.guide-tabs {
  display: flex;
  justify-content: center;
  gap: 12px;
  margin-bottom: 36px;
}

.tab-btn {
  background: var(--surface);
  border: 1px solid var(--border);
  color: var(--text-secondary);
  padding: 10px 24px;
  border-radius: 10px;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.2s;
}

.tab-btn.active {
  background: var(--surface-elevated);
  border-color: var(--accent);
  color: var(--text-primary);
}

.guide-panel {
  display: none;
}

.guide-panel.active {
  display: block;
}

.guide-content {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 20px;
  padding: 36px;
  max-width: 800px;
  margin: 0 auto;
}

.step-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 24px;
}

.step-item {
  display: flex;
  gap: 20px;
}

.step-number {
  width: 36px;
  height: 36px;
  border-radius: 50%;
  background: var(--accent-muted);
  color: var(--accent);
  font-weight: 700;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
  border: 1px solid rgba(99, 102, 241, 0.3);
}

.step-title {
  font-weight: 700;
  font-size: 1.05rem;
  margin-bottom: 4px;
}

.step-desc {
  color: var(--text-secondary);
  font-size: 0.92rem;
}

/* Security Guarantee Banner */
.security-banner {
  margin: 60px 0 80px;
  background: linear-gradient(135deg, rgba(16, 185, 129, 0.1) 0%, rgba(99, 102, 241, 0.05) 100%);
  border: 1px solid rgba(16, 185, 129, 0.25);
  border-radius: 20px;
  padding: 40px;
  text-align: center;
}

.security-title {
  font-size: 1.6rem;
  font-weight: 700;
  margin-bottom: 12px;
}

.security-desc {
  color: var(--text-secondary);
  max-width: 650px;
  margin: 0 auto 20px;
  font-size: 1rem;
}

/* Privacy & Terms Prose Styling */
.prose {
  padding: 60px 0 100px;
  max-width: 840px;
}

.prose h1 {
  font-size: 2.5rem;
  font-weight: 800;
  margin-bottom: 12px;
  letter-spacing: -0.02em;
}

.prose .date-meta {
  color: var(--text-muted);
  font-size: 0.9rem;
  margin-bottom: 40px;
}

.prose h2 {
  font-size: 1.5rem;
  font-weight: 700;
  margin-top: 36px;
  margin-bottom: 14px;
  color: #fff;
  border-bottom: 1px solid var(--border);
  padding-bottom: 8px;
}

.prose p {
  color: var(--text-secondary);
  line-height: 1.7;
  margin-bottom: 18px;
  font-size: 1.02rem;
}

.prose ul {
  margin-bottom: 20px;
  padding-left: 24px;
  color: var(--text-secondary);
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.prose strong {
  color: var(--text-primary);
}

.prose .callout {
  background: var(--surface-elevated);
  border-left: 4px solid var(--positive);
  padding: 18px 24px;
  border-radius: 0 12px 12px 0;
  margin: 24px 0;
}

/* Footer */
.footer {
  border-top: 1px solid var(--border);
  padding: 48px 0;
  background: var(--surface);
  margin-top: auto;
}

.footer-content {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
}

.footer-copy {
  color: var(--text-muted);
  font-size: 0.9rem;
}

.footer-links {
  display: flex;
  gap: 24px;
  list-style: none;
}

.footer-link {
  color: var(--text-secondary);
  text-decoration: none;
  font-size: 0.9rem;
  transition: color 0.2s;
}

.footer-link:hover {
  color: var(--text-primary);
}

@media (max-width: 768px) {
  .nav-links {
    display: none;
  }
  .download-grid {
    grid-template-columns: 1fr;
  }
  .hero {
    padding: 50px 0 40px;
  }
  .download-card {
    padding: 24px;
  }
  .footer-content {
    flex-direction: column;
    text-align: center;
  }
}