/* ============================================================
   全局基础样式
   字体参考苹果中国官网，使用系统中文字体栈
   ============================================================ */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "SF Pro SC", "SF Pro Text",
    "PingFang SC", "Helvetica Neue", "Microsoft YaHei", sans-serif;
  font-size: 16px;
  line-height: 1.5;
  color: #1d1d1f;
  background-color: #fff;
  -webkit-font-smoothing: antialiased;
}

a {
  color: #06c;
  text-decoration: none;
  transition: color 0.2s ease;
}

a:hover {
  color: #0077ed;
  text-decoration: underline;
}

ul {
  list-style: none;
}

/* ============================================================
   顶部导航栏 - 黑色细窄条
   ============================================================ */
.nav-bar {
  position: sticky;
  top: 0;
  z-index: 100;
  background-color: rgba(0, 0, 0, 0.85);
  backdrop-filter: saturate(180%) blur(20px);
  -webkit-backdrop-filter: saturate(180%) blur(20px);
  height: 44px;
}

.nav-container {
  max-width: 1024px;
  height: 100%;
  margin: 0 auto;
  padding: 0 22px;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.nav-logo {
  color: #f5f5f7;
  font-size: 18px;
  font-weight: 500;
  text-decoration: none;
}

.nav-logo:hover {
  color: #fff;
  text-decoration: none;
}

.nav-menu {
  display: flex;
  gap: 32px;
}

.nav-menu a {
  color: #f5f5f7;
  font-size: 14px;
  opacity: 0.8;
  transition: opacity 0.2s ease;
}

.nav-menu a:hover {
  opacity: 1;
  text-decoration: none;
}

/* 移动端汉堡按钮，默认隐藏 */
.nav-toggle {
  display: none;
  background: none;
  border: none;
  color: #f5f5f7;
  font-size: 22px;
  cursor: pointer;
}

/* ============================================================
   Hero 主视觉区
   ============================================================ */
.hero {
  background-color: #fbfbfd;
  padding: 60px 22px 40px;
  text-align: center;
  overflow: hidden;
}

.hero-content {
  max-width: 1024px;
  margin: 0 auto;
}

.hero-title {
  font-size: 56px;
  font-weight: 600;
  letter-spacing: -0.005em;
  line-height: 1.07;
  color: #1d1d1f;
  margin-bottom: 8px;
}

.hero-subtitle {
  font-size: 28px;
  font-weight: 400;
  color: #1d1d1f;
  margin-bottom: 20px;
}

.hero-actions {
  display: flex;
  justify-content: center;
  gap: 24px;
  margin-bottom: 40px;
}

/* 主视觉占位图 */
.hero-image {
  width: 100%;
  height: 480px;
  border-radius: 18px;
  background: linear-gradient(135deg, #e8e8ed 0%, #d2d2d7 100%);
  display: flex;
  align-items: center;
  justify-content: center;
  color: #86868b;
  font-size: 14px;
}

/* ============================================================
   按钮样式
   ============================================================ */
.btn {
  display: inline-block;
  font-size: 17px;
  line-height: 1.18;
  text-decoration: none;
  transition: all 0.2s ease;
  cursor: pointer;
}

.btn-primary {
  padding: 8px 16px;
  background-color: #0071e3;
  color: #fff;
  border-radius: 980px;
  border: none;
}

.btn-primary:hover {
  background-color: #0077ed;
  color: #fff;
  text-decoration: none;
}

.btn-link {
  color: #06c;
  background: none;
}

.btn-link:hover {
  text-decoration: underline;
}

/* ============================================================
   产品双栏区
   ============================================================ */
.products {
  background-color: #fbfbfd;
  padding: 14px 22px;
}

.product-grid {
  max-width: 1440px;
  margin: 0 auto;
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 14px;
}

.product-card {
  background-color: #fff;
  padding: 50px 22px 0;
  border-radius: 18px;
  text-align: center;
  min-height: 580px;
  display: flex;
  flex-direction: column;
}

.product-card.dark {
  background-color: #1d1d1f;
  color: #f5f5f7;
}

.product-card.dark .product-title,
.product-card.dark .product-subtitle {
  color: #f5f5f7;
}

.product-card.dark .btn-link {
  color: #2997ff;
}

.product-title {
  font-size: 40px;
  font-weight: 600;
  letter-spacing: -0.005em;
  line-height: 1.1;
  color: #1d1d1f;
  margin-bottom: 6px;
}

.product-subtitle {
  font-size: 21px;
  font-weight: 400;
  color: #1d1d1f;
  margin-bottom: 14px;
}

.product-actions {
  display: flex;
  justify-content: center;
  gap: 24px;
  margin-bottom: 24px;
}

/* 产品占位图 */
.product-image {
  flex: 1;
  min-height: 320px;
  border-radius: 12px;
  background: linear-gradient(135deg, #f0f0f3 0%, #e0e0e5 100%);
  display: flex;
  align-items: center;
  justify-content: center;
  color: #86868b;
  font-size: 13px;
  margin: 0 -22px;
  margin-bottom: 0;
}

.product-card.dark .product-image {
  background: linear-gradient(135deg, #2a2a2c 0%, #1d1d1f 100%);
  color: #6e6e73;
}

/* ============================================================
   特性介绍区
   ============================================================ */
.features {
  padding: 80px 22px;
  background-color: #fff;
}

.section-title {
  font-size: 40px;
  font-weight: 600;
  text-align: center;
  margin-bottom: 60px;
  color: #1d1d1f;
}

.feature-grid {
  max-width: 1024px;
  margin: 0 auto;
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 40px;
}

.feature-item {
  text-align: center;
}

.feature-icon {
  font-size: 48px;
  margin-bottom: 20px;
}

.feature-item h3 {
  font-size: 22px;
  font-weight: 600;
  margin-bottom: 12px;
  color: #1d1d1f;
}

.feature-item p {
  font-size: 16px;
  color: #515154;
  line-height: 1.6;
}

/* ============================================================
   Footer 底部
   ============================================================ */
.footer {
  background-color: #f5f5f7;
  color: #6e6e73;
  padding: 40px 22px 20px;
  font-size: 12px;
}

.footer-container {
  max-width: 1024px;
  margin: 0 auto;
}

.footer-columns {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 40px;
  margin-bottom: 30px;
}

.footer-col h4 {
  color: #1d1d1f;
  font-size: 12px;
  font-weight: 600;
  margin-bottom: 12px;
}

.footer-col ul li {
  margin-bottom: 8px;
}

.footer-col ul li,
.footer-col ul li a {
  color: #6e6e73;
  font-size: 12px;
  line-height: 1.6;
}

.footer-col ul li a:hover {
  color: #1d1d1f;
  text-decoration: underline;
}

.footer-divider {
  border: none;
  border-top: 1px solid #d2d2d7;
  margin: 20px 0;
}

.footer-bottom {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 12px;
  color: #6e6e73;
  font-size: 12px;
}

.beian {
  display: flex;
  align-items: center;
  gap: 16px;
}

.beian a {
  color: #6e6e73;
  text-decoration: none;
}

.beian a:hover {
  color: #1d1d1f;
  text-decoration: underline;
}

.beian .gongan {
  display: inline-flex;
  align-items: center;
  gap: 4px;
}

.beian .gongan img {
  width: 14px;
  height: 14px;
}

/* ============================================================
   响应式适配
   ============================================================ */
@media (max-width: 768px) {
  .nav-menu {
    display: none;
  }
  .nav-toggle {
    display: block;
  }
  .nav-menu.active {
    display: flex;
    position: absolute;
    top: 44px;
    left: 0;
    right: 0;
    flex-direction: column;
    background-color: rgba(0, 0, 0, 0.95);
    padding: 20px 22px;
    gap: 16px;
  }

  .hero-title {
    font-size: 36px;
  }
  .hero-subtitle {
    font-size: 20px;
  }
  .hero-image {
    height: 240px;
  }

  .product-grid {
    grid-template-columns: 1fr;
  }
  .product-card {
    min-height: 480px;
  }
  .product-title {
    font-size: 28px;
  }
  .product-subtitle {
    font-size: 17px;
  }
  .product-image {
    min-height: 240px;
  }

  .feature-grid {
    grid-template-columns: 1fr;
    gap: 30px;
  }
  .section-title {
    font-size: 28px;
    margin-bottom: 40px;
  }

  .footer-columns {
    grid-template-columns: repeat(2, 1fr);
    gap: 24px;
  }

  .footer-bottom {
    flex-direction: column;
    align-items: flex-start;
  }
  .beian {
    flex-direction: column;
    align-items: flex-start;
    gap: 6px;
  }
}