:root {
    --primary: #0F4C81;
    --secondary: #E5E5EA;
    --accent: #FFA500;
    --text: #333;
    --light: #fff;
    --dark: #222;
    --radius: 12px;
    --shadow: 0 10px 30px rgba(0,0,0,0.1);
    --transition: all 0.3s cubic-bezier(0.25, 0.8, 0.25, 1);
  }

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

  body {
    font-family: 'Roboto', -apple-system, BlinkMacSystemFont, sans-serif;
    line-height: 1.7;
    color: var(--text);
    background: linear-gradient(135deg, #f5f7fa 0%, #e5e5ea 100%);
    overflow-x: hidden;
  }

  .container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 40px 20px;
  }

  .header {
    text-align: center;
    margin-bottom: 60px;
    position: relative;
  }

  .header::after {
    content: '';
    display: block;
    width: 100px;
    height: 4px;
    background: linear-gradient(90deg, var(--primary), var(--accent));
    margin: 20px auto;
    border-radius: 2px;
  }

  h1, h2, h3, h4 {
    font-weight: 700;
    line-height: 1.3;
    margin-bottom: 20px;
    color: var(--dark);
  }

  h1 {
    font-size: 2.5rem;
    background: linear-gradient(90deg, var(--primary), var(--accent));
    -webkit-background-clip: text;
    background-clip: text;
    color: transparent;
    display: inline-block;
  }

  h2 {
    font-size: 1.8rem;
    color: var(--primary);
    position: relative;
    padding-bottom: 10px;
  }

  h2::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 50px;
    height: 3px;
    background: var(--accent);
  }

  h3 {
    font-size: 1.4rem;
    color: var(--primary);
    margin-top: 30px;
  }

  p {
    margin-bottom: 20px;
    font-size: 1.1rem;
  }

  .grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 30px;
    margin: 40px 0;
  }

  .card {
    background: var(--light);
    border-radius: var(--radius);
    padding: 30px;
    box-shadow: var(--shadow);
    transition: var(--transition);
    position: relative;
    overflow: hidden;
  }

  .card:hover {
    transform: translateY(-5px);
    box-shadow: 0 15px 30px rgba(0,0,0,0.15);
  }

  .card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 5px;
    height: 100%;
    background: linear-gradient(to bottom, var(--primary), var(--accent));
  }

  .image-container {
    display: flex;
    flex-wrap: wrap;
    gap: 20px;
    margin: 30px 0;
    justify-content: center;
  }

  .decor-image {
    width: 150px;
    height: 150px;
    object-fit: cover;
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    transition: var(--transition);
  }

  .decor-image:hover {
    transform: scale(1.05);
    box-shadow: 0 15px 30px rgba(0,0,0,0.2);
  }

  pre {
    background: #2d2d2d;
    color: #f8f8f2;
    padding: 20px;
    border-radius: var(--radius);
    overflow-x: auto;
    margin: 25px 0;
    font-size: 0.9rem;
    position: relative;
  }

  pre::before {
    content: 'CSS';
    position: absolute;
    top: 0;
    right: 0;
    background: var(--accent);
    color: var(--light);
    padding: 5px 10px;
    border-radius: 0 0 0 var(--radius);
    font-size: 0.8rem;
  }

  code {
    font-family: 'Fira Code', monospace;
  }

  .note {
    background: rgba(255, 165, 0, 0.1);
    border-left: 4px solid var(--accent);
    padding: 20px;
    margin: 30px 0;
    border-radius: 0 var(--radius) var(--radius) 0;
  }

  .note::before {
    content: '设计提示';
    display: block;
    font-weight: bold;
    color: var(--accent);
    margin-bottom: 10px;
  }

  .footer {
    text-align: center;
    margin-top: 60px;
    padding: 20px;
    color: var(--primary);
    font-size: 0.9rem;
  }

  @media (max-width: 768px) {
    h1 {
      font-size: 2rem;
    }
    h2 {
      font-size: 1.5rem;
    }
    .grid {
      grid-template-columns: 1fr;
    }
  }

  /* Animations */
  @keyframes float {
    0%, 100% {
      transform: translateY(0);
    }
    50% {
      transform: translateY(-10px);
    }
  }

  .floating {
    animation: float 3s ease-in-out infinite;
  }

  /* Navigation */
  .nav-container {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    background: rgba(255,255,255,0.95);
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
    z-index: 1000;
    padding: 15px 0;
  }

  .nav {
    max-width: 1200px;
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0 20px;
  }

  .nav-links {
    display: flex;
    gap: 30px;
  }

  .nav-link {
    color: var(--primary);
    text-decoration: none;
    font-weight: 500;
    transition: var(--transition);
    position: relative;
  }

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

  .nav-link::after {
    content: '';
    position: absolute;
    bottom: -5px;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--accent);
    transition: var(--transition);
  }

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

  .logo {
    font-weight: 700;
    font-size: 1.2rem;
    color: var(--primary);
    text-decoration: none;
  }

  /* Section spacing */
  section {
    padding: 60px 0;
  }

  /* Hero section */
  .hero {
    min-height: 500px;
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
    padding: 100px 20px;
    position: relative;
    overflow: hidden;
  }

  .hero::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: linear-gradient(135deg, rgba(15, 76, 129, 0.8) 0%, rgba(229, 229, 234, 0.8) 100%);
    z-index: -1;
  }

  .hero-content {
    max-width: 800px;
    margin: 0 auto;
  }

  .hero h1 {
    font-size: 3rem;
    margin-bottom: 20px;
  }

  .hero p {
    font-size: 1.2rem;
    color: var(--light);
    margin-bottom: 30px;
  }

  /* Scroll indicator */
  .scroll-down {
    position: absolute;
    bottom: 30px;
    left: 50%;
    transform: translateX(-50%);
    color: var(--light);
    animation: bounce 2s infinite;
  }

  @keyframes bounce {
    0%, 20%, 50%, 80%, 100% {
      transform: translateY(0) translateX(-50%);
    }
    40% {
      transform: translateY(-20px) translateX(-50%);
    }
    60% {
      transform: translateY(-10px) translateX(-50%);
    }
  }