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

:root {
  --primary: #1A237E;
  --primary-light: #3949AB;
  --secondary: #00BFA5;
  --accent: #536DFE;
  --bg: #F5F7FA;
  --text: #1D1D1F;
  --text-secondary: #86868B;
  --card: #fff;
  --danger: #FF3B30;
  --radius: 12px;
  --shadow: 0 2px 12px rgba(0,0,0,0.08);
  --max-width: 1100px;
}

html {
  scroll-behavior: smooth;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "SF Pro", "PingFang SC", "Microsoft YaHei", sans-serif;
  color: var(--text);
  background: var(--bg);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 20px;
}

/* Navigation */
.nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  background: rgba(255,255,255,0.95);
  backdrop-filter: blur(10px);
  z-index: 1000;
  border-bottom: 1px solid rgba(0,0,0,0.06);
}

.nav-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 60px;
}

.nav-logo {
  font-size: 20px;
  font-weight: 700;
  color: var(--primary);
  text-decoration: none;
}

.nav-menu {
  display: flex;
  list-style: none;
  gap: 8px;
}

.nav-menu a {
  text-decoration: none;
  color: var(--text-secondary);
  font-size: 14px;
  padding: 8px 14px;
  border-radius: 8px;
  transition: all 0.2s;
}

.nav-menu a:hover {
  color: var(--primary);
  background: #E8EAF6;
}

.nav-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 4px;
}

.nav-toggle span {
  display: block;
  width: 24px;
  height: 2px;
  background: var(--text);
  border-radius: 2px;
  transition: all 0.3s;
}

/* Hero */
.hero {
  padding: 120px 0 80px;
  background: linear-gradient(135deg, #1A237E 0%, #3949AB 50%, #536DFE 100%);
  color: #fff;
  overflow: hidden;
}

.hero-inner {
  display: flex;
  align-items: center;
  gap: 60px;
}

.hero-text {
  flex: 1;
}

.hero-text h1 {
  font-size: 48px;
  font-weight: 800;
  margin-bottom: 12px;
  letter-spacing: -0.5px;
}

.hero-subtitle {
  font-size: 22px;
  font-weight: 600;
  opacity: 0.9;
  margin-bottom: 16px;
}

.hero-desc {
  font-size: 16px;
  opacity: 0.75;
  margin-bottom: 32px;
  line-height: 1.7;
}

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

.hero-qr {
  display: none;
  margin-top: 28px;
  text-align: center;
}

.hero-qr img {
  width: 120px;
  height: 120px;
  border-radius: 8px;
  background: #fff;
  padding: 8px;
}

.hero-qr span {
  display: block;
  margin-top: 8px;
  font-size: 13px;
  opacity: 0.7;
}

/* Phone Frame */
.phone-frame {
  width: 280px;
  height: 560px;
  background: #1a1a1a;
  border-radius: 40px;
  padding: 12px;
  position: relative;
  box-shadow: 0 20px 60px rgba(0,0,0,0.3);
}

.phone-notch {
  position: absolute;
  top: 20px;
  left: 50%;
  transform: translateX(-50%);
  width: 120px;
  height: 28px;
  background: #1a1a1a;
  border-radius: 0 0 16px 16px;
  z-index: 2;
}

.phone-screen {
  width: 100%;
  height: 100%;
  border-radius: 30px;
  overflow: hidden;
  position: relative;
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 14px 28px;
  border-radius: var(--radius);
  font-size: 15px;
  font-weight: 600;
  text-decoration: none;
  transition: all 0.25s;
  cursor: pointer;
  border: none;
}

.btn-primary {
  background: var(--secondary);
  color: #fff;
}

.btn-primary:hover {
  background: #009e86;
  transform: translateY(-1px);
  box-shadow: 0 4px 16px rgba(0,191,165,0.3);
}

.btn-outline {
  background: transparent;
  color: #fff;
  border: 2px solid rgba(255,255,255,0.3);
}

.btn-outline:hover {
  border-color: #fff;
  background: rgba(255,255,255,0.1);
}

/* Sections */
.section {
  padding: 80px 0;
}

.section-light {
  background: var(--card);
}

.section-title {
  text-align: center;
  font-size: 32px;
  font-weight: 700;
  color: var(--text);
  margin-bottom: 12px;
}

.section-desc {
  text-align: center;
  color: var(--text-secondary);
  font-size: 16px;
  margin-bottom: 48px;
}

/* Features Grid */
.features-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 24px;
}

.feature-card {
  background: var(--card);
  padding: 28px 20px;
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  text-align: center;
  transition: transform 0.25s;
}

.feature-card:hover {
  transform: translateY(-4px);
}

.feature-icon {
  width: 56px;
  height: 56px;
  border-radius: 14px;
  display: flex;
  align-items: center;
  justify-content: center;
  margin: 0 auto 16px;
}

.feature-card h3 {
  font-size: 17px;
  font-weight: 600;
  margin-bottom: 10px;
  color: var(--text);
}

.feature-card p {
  font-size: 14px;
  color: var(--text-secondary);
  line-height: 1.6;
}

/* Screenshots */
.screenshot-carousel {
  overflow: hidden;
  position: relative;
}

.screenshot-track {
  display: flex;
  gap: 24px;
  overflow-x: auto;
  scroll-snap-type: x mandatory;
  -webkit-overflow-scrolling: touch;
  padding: 16px 0 24px;
  scrollbar-width: none;
}

.screenshot-track::-webkit-scrollbar {
  display: none;
}

.screenshot-item {
  flex: 0 0 220px;
  scroll-snap-align: start;
  text-align: center;
}

.phone-frame-sm {
  width: 180px;
  height: 360px;
  background: #1a1a1a;
  border-radius: 28px;
  padding: 8px;
  margin: 0 auto 12px;
  box-shadow: var(--shadow);
}

.screen-placeholder {
  width: 100%;
  height: 100%;
  border-radius: 20px;
  display: flex;
  align-items: center;
  justify-content: center;
}

.screen-label {
  color: #fff;
  font-size: 16px;
  font-weight: 600;
  opacity: 0.9;
}

.screenshot-item p {
  font-size: 13px;
  color: var(--text-secondary);
}

.carousel-dots {
  display: flex;
  justify-content: center;
  gap: 8px;
  margin-top: 12px;
}

.carousel-dots span {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: #ddd;
  cursor: pointer;
  transition: all 0.3s;
}

.carousel-dots span.active {
  background: var(--primary);
  width: 24px;
  border-radius: 4px;
}

/* Download */
.download-grid {
  max-width: 500px;
  margin: 0 auto;
}

.download-card {
  background: var(--card);
  border-radius: var(--radius);
  padding: 36px 28px;
  box-shadow: var(--shadow);
  text-align: center;
}

.download-icon {
  margin-bottom: 16px;
}

.download-card h3 {
  font-size: 20px;
  font-weight: 700;
  margin-bottom: 4px;
}

.download-card > p {
  color: var(--text-secondary);
  font-size: 14px;
  margin-bottom: 24px;
}

.download-buttons {
  display: flex;
  flex-direction: column;
  gap: 12px;
  margin-bottom: 24px;
}

.btn-download {
  justify-content: center;
  font-size: 14px;
  padding: 16px 24px;
}

.btn-recommended {
  background: linear-gradient(135deg, var(--primary) 0%, #3949AB 100%);
  box-shadow: 0 4px 16px rgba(26, 35, 126, 0.3);
  transform: scale(1.03);
}

.download-qr {
  margin: 20px 0;
}

.download-qr img {
  width: 140px;
  height: 140px;
  border-radius: 8px;
  background: var(--bg);
  padding: 8px;
}

.download-qr span {
  display: block;
  margin-top: 8px;
  font-size: 13px;
  color: var(--text-secondary);
}

.changelog {
  text-align: left;
  padding-top: 20px;
  border-top: 1px solid #eee;
}

.changelog h4 {
  font-size: 14px;
  font-weight: 600;
  margin-bottom: 8px;
  color: var(--text);
}

.changelog ul {
  list-style: none;
  padding: 0;
}

.changelog li {
  font-size: 13px;
  color: var(--text-secondary);
  padding: 4px 0;
  padding-left: 16px;
  position: relative;
}

.changelog li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 12px;
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--secondary);
}

/* Guide Tabs */
.guide-tabs {
  max-width: 650px;
  margin: 0 auto;
}

.guide-tab-nav {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
  margin-bottom: 24px;
  justify-content: center;
}

.guide-tab-btn {
  padding: 10px 20px;
  border: 2px solid #e0e0e0;
  background: var(--card);
  border-radius: 8px;
  font-size: 14px;
  font-weight: 500;
  color: var(--text-secondary);
  cursor: pointer;
  transition: all 0.2s;
}

.guide-tab-btn:hover {
  border-color: var(--primary);
  color: var(--primary);
}

.guide-tab-btn.active {
  background: var(--primary);
  border-color: var(--primary);
  color: #fff;
}

.guide-panel {
  display: none;
  background: var(--card);
  border-radius: var(--radius);
  padding: 28px;
  box-shadow: var(--shadow);
}

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

.guide-panel ol {
  padding-left: 20px;
}

.guide-panel li {
  font-size: 14px;
  padding: 6px 0;
  color: var(--text);
  line-height: 1.6;
}

.guide-tip {
  margin-top: 16px;
  padding: 12px 16px;
  background: #FFF8E1;
  border-radius: 8px;
  font-size: 13px;
  color: #795548;
  line-height: 1.5;
}

/* Privacy */
.privacy-content {
  max-width: 720px;
  margin: 0 auto;
  background: var(--card);
  border-radius: var(--radius);
  padding: 36px 32px;
  box-shadow: var(--shadow);
}

.privacy-content h3 {
  font-size: 16px;
  font-weight: 600;
  color: var(--text);
  margin: 20px 0 8px;
}

.privacy-content h3:first-child {
  margin-top: 0;
}

.privacy-content p {
  font-size: 14px;
  color: var(--text-secondary);
  line-height: 1.7;
}

.privacy-date {
  margin-top: 24px;
  text-align: center;
  font-size: 12px !important;
  color: var(--text-secondary) !important;
}

/* Footer */
.footer {
  background: #1a1a2e;
  color: #fff;
  padding: 48px 0 32px;
}

.footer-inner {
  text-align: center;
}

.footer-brand h3 {
  font-size: 22px;
  font-weight: 700;
  margin-bottom: 4px;
}

.footer-brand p {
  font-size: 14px;
  opacity: 0.6;
  margin-bottom: 24px;
}

.footer-links {
  display: flex;
  justify-content: center;
  gap: 24px;
  margin-bottom: 24px;
  flex-wrap: wrap;
}

.footer-links a {
  color: rgba(255,255,255,0.6);
  text-decoration: none;
  font-size: 14px;
  transition: color 0.2s;
}

.footer-links a:hover {
  color: #fff;
}

.footer-copyright {
  font-size: 13px;
  opacity: 0.4;
}

/* Responsive */
@media (max-width: 900px) {
  .features-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .hero-inner {
    flex-direction: column;
    text-align: center;
    gap: 40px;
  }

  .hero-actions {
    justify-content: center;
  }

  .hero-text h1 {
    font-size: 36px;
  }

  .hero-subtitle {
    font-size: 18px;
  }

  .hero-qr {
    display: block;
  }

  .phone-frame {
    display: none;
  }
}

@media (max-width: 640px) {
  .nav-menu {
    position: fixed;
    top: 60px;
    left: 0;
    right: 0;
    background: rgba(255,255,255,0.98);
    flex-direction: column;
    padding: 16px 20px;
    gap: 4px;
    border-bottom: 1px solid #eee;
    display: none;
  }

  .nav-menu.open {
    display: flex;
  }

  .nav-toggle {
    display: flex;
  }

  .hero {
    padding: 100px 0 60px;
  }

  .hero-text h1 {
    font-size: 28px;
  }

  .section {
    padding: 60px 0;
  }

  .section-title {
    font-size: 24px;
  }

  .features-grid {
    grid-template-columns: 1fr;
    gap: 16px;
  }

  .feature-card {
    padding: 20px 16px;
  }

  .download-card {
    padding: 24px 16px;
  }

  .privacy-content {
    padding: 24px 16px;
  }

  .guide-panel {
    padding: 20px 16px;
  }

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