:root {
    --primary: #1E90FF;
    --secondary: #00CED1;
    --accent: #FFA500;
    --dark: #2C3E50;
    --light: #F5F7FA;
    --text: #333;
    --white: #FFFFFF;
  }

  * {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Montserrat', 'Open Sans', sans-serif;
  }

  body {
    background: linear-gradient(135deg, #F5F7FA 0%, #E4E8EB 100%);
    color: var(--text);
    line-height: 1.6;
    overflow-x: hidden;
  }

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

  .header {
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    color: var(--white);
    padding: 60px 0;
    text-align: center;
    position: relative;
    overflow: hidden;
    margin-bottom: 60px;
  }

  .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;
  }

  h1 {
    font-size: 3rem;
    margin-bottom: 20px;
    text-shadow: 2px 2px 4px rgba(0,0,0,0.2);
  }

  .subtitle {
    font-size: 1.2rem;
    max-width: 800px;
    margin: 0 auto 30px;
  }

  .reference-banner {
    background: rgba(255,255,255,0.2);
    padding: 10px;
    border-radius: 4px;
    display: inline-block;
    margin-top: 20px;
    font-size: 0.9rem;
  }

  article {
    background: var(--white);
    border-radius: 12px;
    box-shadow: 0 10px 30px rgba(0,0,0,0.08);
    padding: 60px;
    margin-bottom: 60px;
  }

  h2 {
    color: var(--primary);
    font-size: 2rem;
    margin-bottom: 30px;
    position: relative;
    padding-bottom: 15px;
  }

  h2::after {
    content: "";
    position: absolute;
    bottom: 0;
    left: 0;
    width: 80px;
    height: 4px;
    background: linear-gradient(90deg, var(--primary), var(--secondary));
    border-radius: 2px;
  }

  h3 {
    color: var(--dark);
    font-size: 1.5rem;
    margin: 40px 0 20px;
  }

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

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

  .image-card {
    border-radius: 12px;
    overflow: hidden;
    box-shadow: 0 5px 15px rgba(0,0,0,0.1);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
  }

  .image-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 25px rgba(0,0,0,0.15);
  }

  .image-card img {
    width: 100%;
    height: 300px;
    object-fit: cover;
    display: block;
  }

  pre {
    background: var(--dark);
    color: var(--light);
    padding: 20px;
    border-radius: 8px;
    overflow-x: auto;
    margin: 30px 0;
    font-family: 'Courier New', monospace;
    font-size: 0.9rem;
    line-height: 1.5;
    position: relative;
  }

  pre::before {
    content: "CSS";
    position: absolute;
    top: 0;
    left: 0;
    background: var(--accent);
    color: var(--white);
    padding: 3px 10px;
    border-radius: 0 0 4px 0;
    font-size: 0.8rem;
  }

  code {
    font-family: 'Courier New', monospace;
    background: rgba(0,0,0,0.05);
    padding: 2px 4px;
    border-radius: 3px;
    font-size: 0.9em;
  }

  .nav-tabs {
    display: flex;
    flex-wrap: wrap;
    margin: 40px 0;
    border-bottom: 1px solid #ddd;
  }

  .nav-tab {
    padding: 10px 20px;
    cursor: pointer;
    background: none;
    border: none;
    border-bottom: 3px solid transparent;
    font-weight: 600;
    color: var(--text);
    transition: all 0.3s ease;
  }

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

  .tab-content {
    display: none;
    animation: fadeIn 0.5s ease;
  }

  .tab-content.active {
    display: block;
  }

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

  .floating-button {
    position: fixed;
    bottom: 30px;
    right: 30px;
    width: 60px;
    height: 60px;
    background: linear-gradient(45deg, var(--accent), #FF4500);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--white);
    font-size: 1.5rem;
    box-shadow: 0 5px 15px rgba(0,0,0,0.2);
    cursor: pointer;
    z-index: 100;
    transition: all 0.3s ease;
  }

  .floating-button:hover {
    transform: scale(1.1);
    box-shadow: 0 8px 20px rgba(0,0,0,0.3);
  }

  .footer {
    background: var(--dark);
    color: var(--white);
    padding: 40px 0;
    text-align: center;
  }

  .footer-links {
    display: flex;
    justify-content: center;
    flex-wrap: wrap;
    gap: 20px;
    margin-bottom: 20px;
  }

  .footer-link {
    color: var(--white);
    text-decoration: none;
    transition: color 0.3s ease;
  }

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

  @media (max-width: 768px) {
    h1 {
      font-size: 2rem;
    }
    
    h2 {
      font-size: 1.5rem;
    }
    
    article {
      padding: 30px;
    }
    
    .image-grid {
      grid-template-columns: 1fr;
    }
  }

  /* Additional decorative elements */
  .decorative-line {
    height: 2px;
    background: linear-gradient(90deg, transparent, var(--primary), transparent);
    margin: 40px 0;
  }

  .highlight-box {
    background: linear-gradient(135deg, rgba(30,144,255,0.1), rgba(0,206,209,0.1));
    border-left: 4px solid var(--primary);
    padding: 20px;
    margin: 30px 0;
    border-radius: 0 8px 8px 0;
  }