:root {
    --primary: #0d47a1;
    --secondary: #1976d2;
    --accent: #ff9800;
    --light: #f5f5f5;
    --dark: #333333;
    --text: #333333;
    --white: #ffffff;
    --gray: #e0e0e0;
    --shadow: 0 4px 20px rgba(0,0,0,0.1);
    --transition: all 0.3s ease;
  }

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

  body {
    font-family: 'Roboto', sans-serif;
    color: var(--text);
    line-height: 1.6;
    background: linear-gradient(135deg, #f5f7fa 0%, #e4e8eb 100%);
    overflow-x: hidden;
  }

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

  .header {
    background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
    color: var(--white);
    padding: 80px 0 120px;
    text-align: center;
    position: relative;
    overflow: hidden;
    clip-path: polygon(0 0, 100% 0, 100% 90%, 0 100%);
    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') no-repeat center/cover;
    opacity: 0.1;
    z-index: 0;
  }

  .header-content {
    position: relative;
    z-index: 1;
    max-width: 800px;
    margin: 0 auto;
  }

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

  .subtitle {
    font-size: 1.2rem;
    margin-bottom: 30px;
    opacity: 0.9;
  }

  .notice {
    background-color: var(--accent);
    color: var(--white);
    padding: 15px;
    border-radius: 8px;
    margin: 40px auto;
    max-width: 600px;
    text-align: center;
    box-shadow: var(--shadow);
  }

  .navbar {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    background-color: rgba(13, 71, 161, 0.9);
    backdrop-filter: blur(10px);
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 15px 40px;
    z-index: 1000;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
  }

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

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

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

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

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

  article {
    background-color: var(--white);
    border-radius: 12px;
    padding: 40px;
    margin-bottom: 60px;
    box-shadow: var(--shadow);
  }

  h2 {
    color: var(--primary);
    margin: 40px 0 20px;
    font-size: 2rem;
    position: relative;
    padding-bottom: 10px;
  }

  h2::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 60px;
    height: 3px;
    background: linear-gradient(90deg, var(--primary), var(--accent));
  }

  h3 {
    color: var(--secondary);
    margin: 30px 0 15px;
    font-size: 1.5rem;
  }

  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: var(--shadow);
    transition: var(--transition);
    position: relative;
  }

  .image-card:hover {
    transform: translateY(-10px);
    box-shadow: 0 10px 30px rgba(0,0,0,0.15);
  }

  .image-card img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: var(--transition);
  }

  .image-card:hover img {
    transform: scale(1.05);
  }

  .image-card::after {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: linear-gradient(to bottom, rgba(0,0,0,0.1), rgba(0,0,0,0.3));
    z-index: 1;
  }

  pre {
    background-color: #2d2d2d;
    color: #f8f8f2;
    padding: 20px;
    border-radius: 8px;
    overflow-x: auto;
    margin: 25px 0;
    font-family: 'Courier New', monospace;
    font-size: 0.9rem;
    line-height: 1.5;
    box-shadow: var(--shadow);
  }

  code {
    font-family: 'Courier New', monospace;
    background-color: rgba(13, 71, 161, 0.1);
    padding: 2px 6px;
    border-radius: 4px;
    color: var(--primary);
    font-size: 0.9rem;
  }

  .card-container {
    display: flex;
    gap: 30px;
    margin: 40px 0;
    flex-wrap: wrap;
  }

  .tech-card {
    flex: 1 1 300px;
    background: var(--white);
    border-radius: 12px;
    padding: 30px;
    box-shadow: var(--shadow);
    transition: var(--transition);
    border-top: 4px solid var(--accent);
  }

  .tech-card:hover {
    transform: translateY(-10px);
    box-shadow: 0 15px 30px rgba(0,0,0,0.15);
  }

  .tech-card h4 {
    color: var(--primary);
    margin-bottom: 15px;
    font-size: 1.3rem;
  }

  .tech-card ul {
    padding-left: 20px;
  }

  .tech-card li {
    margin-bottom: 8px;
  }

  .back-to-top {
    position: fixed;
    bottom: 30px;
    right: 30px;
    width: 60px;
    height: 60px;
    background: var(--accent);
    color: var(--white);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.5rem;
    cursor: pointer;
    box-shadow: 0 4px 15px rgba(0,0,0,0.2);
    transition: var(--transition);
    z-index: 999;
    opacity: 0;
    visibility: hidden;
  }

  .back-to-top.active {
    opacity: 1;
    visibility: visible;
  }

  .back-to-top:hover {
    background: var(--primary);
    transform: scale(1.1);
  }

  .footer {
    background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
    color: var(--white);
    padding: 60px 0;
    text-align: center;
    clip-path: polygon(0 10%, 100% 0, 100% 100%, 0 100%);
    margin-top: 80px;
  }

  .footer p {
    opacity: 0.8;
    font-size: 0.9rem;
  }

  @media (max-width: 768px) {
    .header {
      padding: 60px 0 100px;
    }

    h1 {
      font-size: 2.2rem;
    }

    .nav-links {
      gap: 15px;
    }

    article {
      padding: 30px;
    }

    .tech-card {
      flex: 1 1 100%;
    }
  }

  @media (max-width: 480px) {
    .header {
      padding: 50px 0 80px;
      clip-path: polygon(0 0, 100% 0, 100% 95%, 0 100%);
    }

    h1 {
      font-size: 1.8rem;
    }

    .navbar {
      padding: 10px 20px;
    }

    .nav-links {
      display: none;
    }

    article {
      padding: 20px;
    }
  }