/* ========== Reset & Base ========== */
*, *::before, *::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  font-size: 16px;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
    "Hiragino Sans GB", "Microsoft YaHei", "Helvetica Neue", Helvetica, Arial,
    sans-serif;
  color: #333;
  line-height: 1.6;
  background: #fff;
  -webkit-font-smoothing: antialiased;
}

a {
  color: inherit;
  text-decoration: none;
}

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

/* 公安备案图标 */
.beian-icon {
  display: inline-block;
  height: 16px;
  width: auto;
  margin-right: 4px;
  vertical-align: -3px;
}

/* ========== Header / Nav ========== */
.header {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  z-index: 100;
  background: rgba(255, 255, 255, 0.92);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid rgba(0, 0, 0, 0.06);
  transition: box-shadow 0.3s;
}

.header.scrolled {
  box-shadow: 0 2px 20px rgba(0, 0, 0, 0.08);
}

.nav {
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 24px;
  height: 64px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.nav-brand {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 18px;
  font-weight: 700;
  color: #2c3e50;
}

.nav-brand img {
  width: 36px;
  height: 36px;
  border-radius: 8px;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 32px;
  list-style: none;
}

.nav-links a {
  font-size: 15px;
  color: #555;
  transition: color 0.2s;
  position: relative;
}

.nav-links a:hover {
  color: #667eea;
}

.nav-links a::after {
  content: "";
  position: absolute;
  left: 0;
  bottom: -4px;
  width: 0;
  height: 2px;
  background: linear-gradient(135deg, #667eea, #764ba2);
  border-radius: 1px;
  transition: width 0.25s;
}

.nav-links a:hover::after {
  width: 100%;
}

/* Mobile menu toggle */
.nav-toggle {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: 4px;
}

.nav-toggle span {
  display: block;
  width: 22px;
  height: 2px;
  background: #333;
  margin: 5px 0;
  border-radius: 2px;
  transition: 0.3s;
}

/* ========== Hero ========== */
.hero {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: 120px 24px 80px;
  background: linear-gradient(160deg, #f8f9ff 0%, #f0edff 40%, #fdf2f8 100%);
  position: relative;
  overflow: hidden;
}

.hero::before {
  content: "";
  position: absolute;
  top: -200px;
  right: -200px;
  width: 500px;
  height: 500px;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(102, 126, 234, 0.08), transparent 70%);
}

.hero::after {
  content: "";
  position: absolute;
  bottom: -150px;
  left: -150px;
  width: 400px;
  height: 400px;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(118, 75, 162, 0.06), transparent 70%);
}

.hero-content {
  position: relative;
  z-index: 1;
  max-width: 680px;
}

.hero-logo {
  width: 96px;
  height: 96px;
  border-radius: 24px;
  margin: 0 auto 32px;
  box-shadow: 0 8px 32px rgba(102, 126, 234, 0.2);
}

.hero h1 {
  font-size: 42px;
  font-weight: 800;
  color: #2c3e50;
  margin-bottom: 16px;
  letter-spacing: 2px;
}

.hero .slogan {
  font-size: 20px;
  color: #667eea;
  font-weight: 500;
  margin-bottom: 12px;
  letter-spacing: 1px;
}

.hero .desc {
  font-size: 16px;
  color: #777;
  margin-bottom: 40px;
  line-height: 1.8;
}

.hero-buttons {
  display: flex;
  gap: 16px;
  justify-content: center;
  flex-wrap: wrap;
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 14px 32px;
  border-radius: 50px;
  font-size: 16px;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.3s;
  border: none;
}

.btn-primary {
  background: linear-gradient(135deg, #667eea, #764ba2);
  color: #fff;
  box-shadow: 0 4px 20px rgba(102, 126, 234, 0.35);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 30px rgba(102, 126, 234, 0.45);
}

.btn-outline {
  background: #fff;
  color: #667eea;
  border: 2px solid #667eea;
}

.btn-outline:hover {
  background: #667eea;
  color: #fff;
  transform: translateY(-2px);
}

.btn svg {
  width: 20px;
  height: 20px;
  fill: currentColor;
}

/* ========== Section common ========== */
.section {
  padding: 80px 24px;
}

.section-inner {
  max-width: 1100px;
  margin: 0 auto;
}

.section-title {
  text-align: center;
  margin-bottom: 56px;
}

.section-title h2 {
  font-size: 32px;
  font-weight: 700;
  color: #2c3e50;
  margin-bottom: 12px;
}

.section-title p {
  font-size: 16px;
  color: #888;
}

/* ========== Features ========== */
.features {
  background: #fff;
}

.features-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 32px;
}

.feature-card {
  padding: 36px 28px;
  border-radius: 16px;
  background: #fafbff;
  border: 1px solid rgba(102, 126, 234, 0.08);
  transition: all 0.3s;
}

.feature-card:hover {
  transform: translateY(-4px);
  box-shadow: 0 12px 36px rgba(102, 126, 234, 0.1);
  border-color: rgba(102, 126, 234, 0.15);
}

.feature-icon {
  width: 56px;
  height: 56px;
  border-radius: 14px;
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 20px;
  font-size: 28px;
}

.feature-icon.purple {
  background: linear-gradient(135deg, rgba(102, 126, 234, 0.12), rgba(118, 75, 162, 0.12));
}

.feature-icon.pink {
  background: linear-gradient(135deg, rgba(236, 72, 153, 0.1), rgba(244, 114, 182, 0.1));
}

.feature-icon.blue {
  background: linear-gradient(135deg, rgba(59, 130, 246, 0.1), rgba(96, 165, 250, 0.1));
}

.feature-icon.green {
  background: linear-gradient(135deg, rgba(34, 197, 94, 0.1), rgba(74, 222, 128, 0.1));
}

.feature-icon.orange {
  background: linear-gradient(135deg, rgba(249, 115, 22, 0.1), rgba(251, 146, 60, 0.1));
}

.feature-icon.teal {
  background: linear-gradient(135deg, rgba(20, 184, 166, 0.1), rgba(45, 212, 191, 0.1));
}

.feature-card h3 {
  font-size: 18px;
  font-weight: 600;
  color: #2c3e50;
  margin-bottom: 10px;
}

.feature-card p {
  font-size: 14px;
  color: #777;
  line-height: 1.7;
}

/* ========== Download ========== */
.download {
  background: linear-gradient(160deg, #f8f9ff, #f3f0ff);
}

.download-box {
  max-width: 600px;
  margin: 0 auto;
  text-align: center;
  padding: 48px 40px;
  background: #fff;
  border-radius: 24px;
  box-shadow: 0 8px 40px rgba(102, 126, 234, 0.1);
}

.download-box h3 {
  font-size: 24px;
  font-weight: 700;
  color: #2c3e50;
  margin-bottom: 12px;
}

.download-box .version {
  font-size: 14px;
  color: #aaa;
  margin-bottom: 8px;
}

.download-box .tip {
  font-size: 14px;
  color: #999;
  margin-bottom: 32px;
}

.download-buttons {
  display: flex;
  gap: 16px;
  justify-content: center;
  flex-wrap: wrap;
}

.download-btn {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  padding: 14px 28px;
  border-radius: 14px;
  font-size: 15px;
  font-weight: 600;
  transition: all 0.3s;
  cursor: pointer;
  border: none;
}

.download-btn.android {
  background: linear-gradient(135deg, #667eea, #764ba2);
  color: #fff;
  box-shadow: 0 4px 16px rgba(102, 126, 234, 0.3);
}

.download-btn.android:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 24px rgba(102, 126, 234, 0.4);
}

.download-btn.ios {
  background: #1a1a1a;
  color: #fff;
  box-shadow: 0 4px 16px rgba(0, 0, 0, 0.15);
}

.download-btn.ios:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.2);
}

.download-btn svg {
  width: 22px;
  height: 22px;
  fill: currentColor;
}

/* ========== About ========== */
.about {
  background: #fff;
}

.about-content {
  max-width: 700px;
  margin: 0 auto;
  text-align: center;
}

.about-content p {
  font-size: 16px;
  color: #666;
  line-height: 2;
  margin-bottom: 16px;
}

.about-info {
  margin-top: 40px;
  display: flex;
  justify-content: center;
  gap: 48px;
  flex-wrap: wrap;
}

.about-info-item {
  text-align: center;
}

.about-info-item .label {
  font-size: 13px;
  color: #aaa;
  margin-bottom: 4px;
}

.about-info-item .value {
  font-size: 15px;
  color: #555;
  font-weight: 500;
}

/* ========== Footer ========== */
.footer {
  background: #1a1a2e;
  color: rgba(255, 255, 255, 0.6);
  padding: 40px 24px;
  text-align: center;
}

.footer-inner {
  max-width: 1100px;
  margin: 0 auto;
}

.footer-links {
  display: flex;
  justify-content: center;
  gap: 24px;
  margin-bottom: 20px;
  flex-wrap: wrap;
}

.footer-links a {
  font-size: 14px;
  color: rgba(255, 255, 255, 0.5);
  transition: color 0.2s;
}

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

.footer-divider {
  height: 1px;
  background: rgba(255, 255, 255, 0.08);
  margin-bottom: 20px;
}

.footer-copy {
  font-size: 13px;
  color: rgba(255, 255, 255, 0.35);
  line-height: 2;
}

.footer-copy a {
  color: rgba(255, 255, 255, 0.5);
}

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

/* ========== Legal pages ========== */
.legal-page {
  min-height: 100vh;
  padding: 100px 24px 60px;
  background: #fafbff;
}

.legal-content {
  max-width: 800px;
  margin: 0 auto;
  background: #fff;
  border-radius: 16px;
  padding: 48px;
  box-shadow: 0 4px 24px rgba(0, 0, 0, 0.04);
}

.legal-content h1 {
  font-size: 28px;
  font-weight: 700;
  color: #2c3e50;
  margin-bottom: 8px;
}

.legal-content .update-date {
  font-size: 14px;
  color: #aaa;
  margin-bottom: 32px;
}

.legal-content h2 {
  font-size: 20px;
  font-weight: 600;
  color: #2c3e50;
  margin-top: 32px;
  margin-bottom: 12px;
}

.legal-content h3 {
  font-size: 17px;
  font-weight: 600;
  color: #444;
  margin-top: 24px;
  margin-bottom: 8px;
}

.legal-content p {
  font-size: 15px;
  color: #555;
  line-height: 1.9;
  margin-bottom: 12px;
}

.legal-content ul {
  padding-left: 20px;
  margin-bottom: 12px;
}

.legal-content li {
  font-size: 15px;
  color: #555;
  line-height: 1.9;
  margin-bottom: 4px;
}

/* ========== Responsive ========== */
@media (max-width: 768px) {
  .nav-links {
    display: none;
    position: absolute;
    top: 64px;
    left: 0;
    right: 0;
    background: #fff;
    flex-direction: column;
    padding: 16px 24px;
    gap: 16px;
    border-bottom: 1px solid #eee;
    box-shadow: 0 8px 24px rgba(0, 0, 0, 0.06);
  }

  .nav-links.active {
    display: flex;
  }

  .nav-toggle {
    display: block;
  }

  .hero {
    padding: 100px 20px 60px;
    min-height: auto;
  }

  .hero h1 {
    font-size: 30px;
  }

  .hero .slogan {
    font-size: 17px;
  }

  .hero-logo {
    width: 72px;
    height: 72px;
    border-radius: 18px;
  }

  .features-grid {
    grid-template-columns: 1fr;
    gap: 20px;
  }

  .section {
    padding: 56px 20px;
  }

  .section-title h2 {
    font-size: 26px;
  }

  .download-box {
    padding: 32px 24px;
  }

  .download-buttons {
    flex-direction: column;
    align-items: center;
  }

  .about-info {
    gap: 24px;
  }

  .legal-content {
    padding: 28px 20px;
  }

  .legal-content h1 {
    font-size: 22px;
  }

  .footer-links {
    gap: 16px;
  }
}