:root {
    --primary-color: #1E3A8A;
    --accent-color: #FBBF24;
    --background-color: #FFFFFF;
    --secondary-color: #6B46C1;
    --text-color: #333333;
    --light-gray: #F5F7FA;
    --dark-gray: #4A5568;
    --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', sans-serif;
    line-height: 1.6;
    color: var(--text-color);
    background-color: var(--light-gray);
    overflow-x: hidden;
  }

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

  header {
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: white;
    padding: 2rem 0;
    margin-bottom: 3rem;
    position: relative;
    overflow: hidden;
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.1);
  }

  header::before {
    content: "";
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: url('https://images.gptkong.com/demo/sample1.png') no-repeat center right/contain;
    opacity: 0.1;
  }

  .header-content {
    position: relative;
    z-index: 1;
    display: flex;
    flex-direction: column;
    align-items: flex-start;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
  }

  h1 {
    font-size: 2.5rem;
    margin-bottom: 1rem;
    text-shadow: 0 2px 4px rgba(0, 0, 0, 0.2);
  }

  .tagline {
    font-size: 1.2rem;
    margin-bottom: 2rem;
    max-width: 700px;
  }

  .notice {
    background-color: rgba(255, 255, 255, 0.2);
    padding: 10px 15px;
    border-radius: 4px;
    font-size: 0.9rem;
    margin-top: 2rem;
    backdrop-filter: blur(5px);
  }

  article {
    background-color: white;
    border-radius: 8px;
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.05);
    padding: 3rem;
    margin-bottom: 3rem;
    position: relative;
  }

  article::before {
    content: "";
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 5px;
    background: linear-gradient(90deg, var(--primary-color), var(--accent-color));
    border-radius: 8px 8px 0 0;
  }

  h2 {
    color: var(--primary-color);
    font-size: 1.8rem;
    margin-bottom: 1.5rem;
    position: relative;
    padding-bottom: 10px;
  }

  h2::after {
    content: "";
    position: absolute;
    bottom: 0;
    left: 0;
    width: 60px;
    height: 3px;
    background: var(--accent-color);
  }

  h3 {
    color: var(--secondary-color);
    font-size: 1.4rem;
    margin: 2rem 0 1rem;
  }

  p {
    margin-bottom: 1.5rem;
    font-size: 1.1rem;
    line-height: 1.7;
  }

  .image-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
    margin: 3rem 0;
  }

  .image-card {
    border-radius: 8px;
    overflow: hidden;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.1);
    transition: var(--transition);
  }

  .image-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 25px rgba(0, 0, 0, 0.15);
  }

  .image-card img {
    width: 100%;
    height: auto;
    display: block;
    transition: var(--transition);
  }

  .image-card:hover img {
    transform: scale(1.03);
  }

  pre {
    background: #282c34;
    color: #abb2bf;
    padding: 1.5rem;
    border-radius: 8px;
    overflow-x: auto;
    margin: 2rem 0;
    font-size: 0.95rem;
    line-height: 1.5;
    position: relative;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.1);
  }

  pre::before {
    content: "CSS";
    position: absolute;
    top: 0;
    left: 0;
    background: var(--accent-color);
    color: white;
    padding: 0.2rem 0.8rem;
    font-size: 0.8rem;
    border-radius: 0 0 4px 0;
  }

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

  .nav-tabs {
    display: flex;
    margin-bottom: 2rem;
    border-bottom: 1px solid #e2e8f0;
  }

  .nav-tab {
    padding: 0.8rem 1.5rem;
    cursor: pointer;
    border-bottom: 3px solid transparent;
    transition: var(--transition);
    font-weight: 500;
    color: var(--dark-gray);
  }

  .nav-tab:hover {
    color: var(--primary-color);
  }

  .nav-tab.active {
    color: var(--primary-color);
    border-bottom-color: var(--accent-color);
  }

  .content-section {
    display: none;
  }

  .content-section.active {
    display: block;
    animation: fadeIn 0.5s ease;
  }

  @keyframes fadeIn {
    from { opacity: 0; transform: translateY(10px); }
    to { opacity: 1; transform: translateY(0); }
  }

  .summary {
    background: linear-gradient(135deg, rgba(30, 58, 138, 0.05), rgba(251, 191, 36, 0.05)));
    padding: 2rem;
    border-radius: 8px;
    margin: 3rem 0;
    border-left: 4px solid var(--accent-color);
  }

  .summary h3 {
    color: var(--primary-color);
    margin-top: 0;
  }

  footer {
    background-color: var(--primary-color);
    color: white;
    padding: 2rem 0;
    text-align: center;
    margin-top: 3rem;
  }

  .footer-content {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
  }

  .footer-links {
    display: flex;
    justify-content: center;
    flex-wrap: wrap;
    margin: 1rem 0;
  }

  .footer-link {
    color: white;
    margin: 0 1rem;
    text-decoration: none;
    transition: var(--transition);
  }

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

  @media (max-width: 768px) {
    h1 {
      font-size: 2rem;
    }
    
    article {
      padding: 2rem;
    }
    
    .image-grid {
      grid-template-columns: 1fr;
    }
    
    pre {
      padding: 1rem;
      font-size: 0.85rem;
    }
  }

  @media (max-width: 480px) {
    h1 {
      font-size: 1.8rem;
    }
    
    article {
      padding: 1.5rem;
    }
    
    .nav-tabs {
      flex-wrap: wrap;
    }
    
    .nav-tab {
      padding: 0.6rem 1rem;
      font-size: 0.9rem;
    }
  }