/* 1. 全局定义与变量 */
:root {
  --primary-teal: #008080; /* 核心青色 */
  --primary-dark: #006666; /* 深青色，用于悬停 */
  --light-teal: #f0f9f9; /* 极浅青色背景 (Uzero 风格区块) */
  --soft-teal: #e6f2f2; /* 辅助浅青色 (用于页脚或边框) */
  --text-main: #1a202c; /* 深度灰，比纯黑更高级 */
  --text-muted: #4a5568; /* 辅助文字颜色 */
  --white: #ffffff;
  --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

/* 2. 基础重置 */
* {
  box-sizing: border-box;
  -webkit-font-smoothing: antialiased;
}

html {
  scroll-behavior: smooth; /* 平滑滚动 */
}

html,
body {
  margin: 0;
  padding: 0;
  height: 100%;
}

body {
  display: flex;
  flex-direction: column; /* 垂直布局，确保 footer 到底部 */
  font-family:
    -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue",
    Arial, sans-serif;
  color: var(--text-main);
  line-height: 1.8;
  background-color: var(--white);

  -webkit-font-smoothing: antialiased; /* macOS/iOS 字体平滑 */
  -moz-osx-font-smoothing: grayscale; /* Firefox on macOS 字体平滑 */
  text-rendering: optimizeLegibility; /* 优化文本可读性 */
}

/* 3. 布局核心：内容区自动撑开 */
main {
  flex: 1 0 auto; /* 关键：解决 PC 端底部空白问题 */
}

/* 4. 导航栏 (Sticky Navbar) */
nav {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 1.2rem 8%;
  background: rgba(255, 255, 255, 0.85);
  backdrop-filter: blur(12px); /* 磨砂玻璃效果 */
  position: sticky;
  top: 0;
  z-index: 1000;
  border-bottom: 1px solid rgba(0, 128, 128, 0.08);
}

.logo {
  font-size: 1.4rem;
  font-weight: 600;
  color: var(--primary-teal);
  text-decoration: none;
  letter-spacing: -0.5px;
}

.logo-image {
  height: 32px;
}

.logo-container {
  display: flex;
  align-items: center;
  gap: 0.2rem;
}

.nav-links {
  display: flex;
  gap: 2.5rem;
}

.nav-links a {
  text-decoration: none;
  color: var(--text-main);
  font-size: 0.95rem;
  font-weight: 500;
  transition: var(--transition);
}

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

/* 5. 通用区块容器 (Uzero 风格) */
.section {
  padding: 100px 8%;
  display: flex;
  flex-direction: column;
  align-items: center;
}

.container {
  max-width: 1100px;
  width: 100%;
  margin: 0 auto;
}

/* 6. Hero 区域 (极简风格) */
.hero {
  background: radial-gradient(
    circle at top right,
    var(--light-teal),
    var(--white)
  );
  padding-top: 140px;
  padding-bottom: 100px;
  text-align: center;
}

.hero h1 {
  font-size: 3.5rem;
  font-weight: 800;
  margin-bottom: 1.5rem;
  letter-spacing: -2px;
  line-height: 1.2;
}

.hero p {
  font-size: 1.25rem;
  color: var(--text-muted);
  max-width: 700px;
  margin: 0 auto 2.5rem;
}

/* 7. 按钮 (Pill Button) */
.btn {
  display: inline-block;
  background: var(--primary-teal);
  color: var(--white);
  padding: 14px 40px;
  border-radius: 50px;
  text-decoration: none;
  font-weight: 600;
  transition: var(--transition);
  box-shadow: 0 4px 15px rgba(0, 128, 128, 0.2);
}

.btn:hover {
  background: var(--primary-dark);
  transform: translateY(-2px);
  box-shadow: 0 6px 20px rgba(0, 128, 128, 0.3);
}

/* 8. 产品矩阵网格 (Responsive Grid) */
.feature-row {
  background-color: var(--light-teal);
}

.product-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  gap: 2.5rem;
  margin-top: 4rem;
}

.product-card {
  background: var(--white);
  padding: 3rem;
  border-radius: 24px;
  border: 1px solid rgba(0, 128, 128, 0.05);
  transition: var(--transition);
  display: flex;
  flex-direction: column;
  text-align: left;
}

.product-card:hover {
  transform: translateY(-8px);
  box-shadow: 0 20px 40px rgba(0, 128, 128, 0.08);
}

.product-tag {
  display: inline-block;
  padding: 5px 14px;
  background: var(--light-teal);
  color: var(--primary-teal);
  border-radius: 30px;
  font-size: 0.75rem;
  font-weight: 700;
  margin-bottom: 1.5rem;
  width: fit-content;
}

.product-card h3 {
  font-size: 1.6rem;
  margin: 0 0 1rem 0;
}

.product-card p {
  font-size: 1rem;
  color: var(--text-muted);
  margin-bottom: 2rem;
  flex-grow: 1;
}

.link-arrow {
  color: var(--primary-teal);
  text-decoration: none;
  font-weight: 700;
  display: inline-flex;
  align-items: center;
}

/* 9. 页脚 (Footer) */
footer {
  flex-shrink: 0;
  background-color: #f8fafc;
  padding: 4rem 8%;
  text-align: center;
  border-top: 1px solid var(--soft-teal);
}

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

footer a {
  font-size: 0.8rem;
  color: var(--text-muted);
}

/* 10. 响应式适配 (Media Queries) */
@media (max-width: 768px) {
  nav {
    padding: 5%;
  }

  .logo-image {
    height: 16px;
  }

  .logo {
    font-size: 12px;
  }

  .nav-links {
    gap: 1.2rem;
  }

  .nav-links a {
    font-size: 0.85rem;
  }

  .hero {
    padding-top: 2rem;
    padding-bottom: 1rem;
  }

  .hero p {
    font-size: 1rem;
    margin-bottom: 0;
  }

  .hero h1 {
    font-size: 2rem;
  }

  .section {
    padding: 5%;
  }

  .product-grid {
    margin-top: 1rem;
  }

  .product-card {
    padding: 2rem;
  }
}

/* 动画类：配合 JS 淡入效果 */
.reveal {
  opacity: 0;
  transform: translateY(30px);
  transition: all 0.8s ease-out;
}

.reveal.active {
  opacity: 1;
  transform: translateY(0);
}