@import url('https://fonts.googleapis.com/css2?family=Roboto:wght@400;700&display=swap');
  
  :root {
    --primary: #2E4053;
    --secondary: #85C1E9;
    --accent: #2ECC71;
    --highlight: #F39C12;
    --bg: #f8f9fa;
    --text: #333;
    --card-bg: #fff;
    --shadow: 0 4px 20px rgba(0,0,0,0.08);
  }
  
  * {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
  }
  
  body {
    font-family: 'Roboto', sans-serif;
    line-height: 1.6;
    color: var(--text);
    background: var(--bg);
    overflow-x: hidden;
  }
  
  .container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
  }
  
  /* Header */
  .header {
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    color: white;
    padding: 2rem 0;
    text-align: center;
    position: relative;
    overflow: hidden;
  }
  
  .header::before {
    content: "";
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: url('https://images.gptkong.com/demo/sample1.png') center/cover no-repeat;
    opacity: 0.1;
    z-index: 0;
  }
  
  .header-content {
    position: relative;
    z-index: 1;
    max-width: 800px;
    margin: 0 auto;
  }
  
  .header h1 {
    font-size: 2.5rem;
    margin-bottom: 1rem;
    text-shadow: 0 2px 4px rgba(0,0,0,0.2);
  }
  
  .header p {
    font-size: 1.2rem;
    opacity: 0.9;
    margin-bottom: 2rem;
  }
  
  .notice {
    background: rgba(255,255,255,0.2);
    padding: 1rem;
    border-radius: 8px;
    display: inline-block;
    backdrop-filter: blur(5px);
    margin-top: 1rem;
  }
  
  /* Navigation */
  .nav {
    display: flex;
    justify-content: center;
    background: var(--primary);
    position: sticky;
    top: 0;
    z-index: 100;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
  }
  
  .nav-list {
    display: flex;
    list-style: none;
    max-width: 1200px;
    width: 100%;
    padding: 0 20px;
  }
  
  .nav-item {
    flex: 1;
    text-align: center;
  }
  
  .nav-link {
    color: white;
    text-decoration: none;
    display: block;
    padding: 1rem;
    transition: all 0.3s ease;
    font-weight: 500;
  }
  
  .nav-link:hover {
    background: rgba(255,255,255,0.1);
  }
  
  /* Main Content */
  .main {
    padding: 3rem 0;
  }
  
  article {
    background: white;
    border-radius: 12px;
    box-shadow: var(--shadow);
    padding: 2.5rem;
    margin-bottom: 3rem;
  }
  
  article h2 {
    color: var(--primary);
    margin: 2rem 0 1.5rem;
    font-size: 1.8rem;
    position: relative;
    padding-bottom: 0.5rem;
  }
  
  article h2::after {
    content: "";
    position: absolute;
    bottom: 0;
    left: 0;
    width: 60px;
    height: 3px;
    background: linear-gradient(90deg, var(--secondary), var(--accent));
    border-radius: 3px;
  }
  
  article h3 {
    color: var(--primary);
    margin: 1.5rem 0 1rem;
    font-size: 1.4rem;
  }
  
  article p {
    margin-bottom: 1.5rem;
    font-size: 1.1rem;
  }
  
  article ol, article ul {
    margin-bottom: 1.5rem;
    padding-left: 2rem;
  }
  
  article li {
    margin-bottom: 0.5rem;
  }
  
  /* Code Blocks */
  pre {
    background: #f5f7fa;
    border-radius: 8px;
    padding: 1.5rem;
    margin: 1.5rem 0;
    overflow: auto;
    border-left: 4px solid var(--secondary);
  }
  
  code {
    font-family: 'Roboto Mono', monospace;
    font-size: 0.9rem;
    color: #333;
  }
  
  /* Tables */
  table {
    width: 100%;
    border-collapse: collapse;
    margin: 1.5rem 0;
    box-shadow: 0 2px 10px rgba(0,0,0,0.05);
  }
  
  th, td {
    padding: 1rem;
    text-align: left;
    border-bottom: 1px solid #eee;
  }
  
  th {
    background: var(--primary);
    color: white;
    font-weight: 500;
  }
  
  tr:nth-child(even) {
    background: #f9f9f9;
  }
  
  /* Image Gallery */
  .gallery {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 1.5rem;
    margin: 2rem 0;
  }
  
  .gallery-item {
    border-radius: 8px;
    overflow: hidden;
    box-shadow: var(--shadow);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
  }
  
  .gallery-item:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 25px rgba(0,0,0,0.1);
  }
  
  .gallery-img {
    width: 100%;
    height: 200px;
    object-fit: cover;
    display: block;
  }
  
  /* Footer */
  .footer {
    background: var(--primary);
    color: white;
    padding: 3rem 0;
    text-align: center;
  }
  
  .footer-content {
    max-width: 800px;
    margin: 0 auto;
  }
  
  .footer p {
    margin-bottom: 1rem;
    opacity: 0.8;
  }
  
  /* Responsive */
  @media (max-width: 768px) {
    .nav-list {
      flex-direction: column;
    }
    
    .nav-item {
      flex: none;
    }
    
    article {
      padding: 1.5rem;
    }
    
    .header h1 {
      font-size: 2rem;
    }
  }
  
  /* Animations */
  @keyframes fadeIn {
    from { opacity: 0; transform: translateY(20px); }
    to { opacity: 1; transform: translateY(0); }
  }
  
  .fade-in {
    animation: fadeIn 0.6s ease forwards;
  }
  
  .delay-1 { animation-delay: 0.2s; }
  .delay-2 { animation-delay: 0.4s; }
  .delay-3 { animation-delay: 0.6s; }
  
  /* Special Elements */
  .highlight-box {
    background: linear-gradient(135deg, rgba(46, 64, 83, 0.05), rgba(133, 193, 233, 0.05));
    border-left: 4px solid var(--highlight);
    padding: 1.5rem;
    margin: 2rem 0;
    border-radius: 0 8px 8px 0;
  }
  
  .color-swatch {
    display: inline-block;
    width: 20px;
    height: 20px;
    border-radius: 50%;
    margin-right: 5px;
    vertical-align: middle;
    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
  }