:root {
    --primary: #032B44;
    --secondary: #D4AF37;
    --light: #FFFFFF;
    --gray: #F5F5F5;
    --transition: all 0.3s cubic-bezier(0.25, 0.8, 0.25, 1);
  }

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

  body {
    background: var(--gray);
    color: #333;
    line-height: 1.6;
    overflow-x: hidden;
  }

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

  header {
    background: linear-gradient(135deg, var(--primary), #0A4B78);
    color: var(--light);
    padding: 80px 0 120px;
    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;
  }

  h1, h2, h3, h4 {
    font-family: 'Helvetica', sans-serif;
    font-weight: bold;
    margin-bottom: 1.5rem;
  }

  h1 {
    font-size: 2.8rem;
    position: relative;
    display: inline-block;
    z-index: 1;
  }

  h1::after {
    content: "";
    position: absolute;
    bottom: -10px;
    left: 0;
    width: 100%;
    height: 4px;
    background: var(--secondary);
    transform: scaleX(0);
    transform-origin: right;
    transition: transform 0.6s ease;
  }

  h1:hover::after {
    transform: scaleX(1);
    transform-origin: left;
  }

  h2 {
    font-size: 2.2rem;
    color: var(--primary);
    margin-top: 3rem;
    padding-bottom: 1rem;
    border-bottom: 2px solid rgba(3, 43, 68, 0.1);
  }

  h3 {
    font-size: 1.8rem;
    color: var(--primary);
    margin-top: 2rem;
  }

  p {
    font-size: 1.1rem;
    margin-bottom: 1.5rem;
    color: #444;
  }

  .design-notice {
    background: rgba(212, 175, 55, 0.1);
    border-left: 4px solid var(--secondary);
    padding: 15px;
    margin: 30px 0;
    font-style: italic;
    border-radius: 0 4px 4px 0;
  }

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

  .image-card {
    background: var(--light);
    border-radius: 8px;
    overflow: hidden;
    box-shadow: 0 10px 20px rgba(0,0,0,0.1);
    transition: var(--transition);
  }

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

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

  .image-card .caption {
    padding: 20px;
    background: var(--light);
  }

  pre {
    background: #1E1E1E;
    color: #F8F8F2;
    padding: 20px;
    border-radius: 6px;
    overflow-x: auto;
    margin: 25px 0;
    font-family: 'Courier New', monospace;
    font-size: 0.95rem;
    line-height: 1.5;
    position: relative;
  }

  pre::before {
    content: "CSS";
    position: absolute;
    top: 0;
    right: 0;
    background: var(--secondary);
    color: var(--primary);
    padding: 3px 10px;
    font-size: 0.8rem;
    border-radius: 0 0 0 6px;
  }

  code {
    font-family: 'Courier New', monospace;
    background: rgba(212, 175, 55, 0.1);
    padding: 2px 6px;
    border-radius: 3px;
    font-size: 0.9rem;
  }

  .content-block {
    background: var(--light);
    padding: 40px;
    border-radius: 8px;
    box-shadow: 0 5px 15px rgba(0,0,0,0.05);
    margin-bottom: 60px;
    position: relative;
  }

  .content-block::after {
    content: "";
    position: absolute;
    bottom: -20px;
    left: 5%;
    width: 90%;
    height: 1px;
    background: linear-gradient(to right, transparent, rgba(212, 175, 55, 0.5), transparent);
  }

  .highlight {
    background: linear-gradient(135deg, rgba(3, 43, 68, 0.05), rgba(212, 175, 55, 0.05));
    padding: 30px;
    border-radius: 8px;
    margin: 30px 0;
    border-left: 4px solid var(--secondary);
  }

  .nav-tabs {
    display: flex;
    justify-content: center;
    margin: 40px 0;
    flex-wrap: wrap;
  }

  .nav-tab {
    padding: 12px 25px;
    margin: 0 10px;
    background: transparent;
    border: none;
    color: var(--primary);
    font-weight: bold;
    cursor: pointer;
    position: relative;
    transition: var(--transition);
  }

  .nav-tab::after {
    content: "";
    position: absolute;
    bottom: 0;
    left: 0;
    width: 0;
    height: 3px;
    background: var(--secondary);
    transition: var(--transition);
  }

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

  .nav-tab.active {
    color: var(--secondary);
  }

  .nav-tab.active::after {
    width: 100%;
  }

  .color-swatch {
    display: inline-block;
    width: 24px;
    height: 24px;
    border-radius: 50%;
    vertical-align: middle;
    margin-right: 8px;
    box-shadow: 0 2px 5px rgba(0,0,0,0.2);
  }

  footer {
    text-align: center;
    padding: 40px 0;
    background: var(--primary);
    color: var(--light);
    margin-top: 80px;
  }

  @media (max-width: 768px) {
    h1 {
      font-size: 2.2rem;
    }
    h2 {
      font-size: 1.8rem;
    }
    h3 {
      font-size: 1.5rem;
    }
    .content-block {
      padding: 30px 20px;
    }
    .image-grid {
      grid-template-columns: 1fr;
    }
  }