:root {
    --primary-color: #3a7bd5;
    --secondary-color: #8e44ad;
    --accent-color-1: #e67e22;
    --accent-color-2: #2ecc71;
    --background-color: #f5f5f5;
    --text-color: #333333;
    --card-shadow: 0 10px 30px rgba(0,0,0,0.1);
    --transition: all 0.4s cubic-bezier(0.175, 0.885, 0.32, 1.275);
  }

  @font-face {
    font-family: 'Roboto';
    src: url('https://fonts.googleapis.com/css2?family=Roboto:wght@300;400;500;700&display=swap');
  }

  body {
    background: linear-gradient(135deg, #f5f7fa 0%, #e4e8f0 100%);
    color: var(--text-color);
    font-family: 'Roboto', sans-serif;
    line-height: 1.6;
    margin: 0;
    padding: 0;
    overflow-x: hidden;
  }

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

  .header {
    background: linear-gradient(45deg, var(--primary-color), var(--secondary-color));
    color: white;
    padding: 40px 0;
    text-align: center;
    position: relative;
    overflow: hidden;
    border-radius: 0 0 20px 20px;
    box-shadow: var(--card-shadow);
    margin-bottom: 50px;
  }

  .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: 2.5rem;
    margin-bottom: 20px;
    text-shadow: 0 2px 4px rgba(0,0,0,0.2);
  }

  .tagline {
    font-size: 1.2rem;
    opacity: 0.9;
    max-width: 800px;
    margin: 0 auto 30px;
  }

  .notice {
    background-color: rgba(255,255,255,0.2);
    padding: 15px;
    border-radius: 8px;
    display: inline-block;
    font-size: 0.9rem;
    backdrop-filter: blur(5px);
  }

  .main-content {
    display: grid;
    grid-template-columns: 1fr 300px;
    gap: 40px;
    margin-bottom: 60px;
  }

  @media (max-width: 1024px) {
    .main-content {
      grid-template-columns: 1fr;
    }
  }

  article {
    background: white;
    border-radius: 15px;
    padding: 40px;
    box-shadow: var(--card-shadow);
    position: relative;
    overflow: hidden;
  }

  article::after {
    content: '';
    position: absolute;
    top: 0;
    right: 0;
    width: 100px;
    height: 100px;
    background: url('https://images.gptkong.com/demo/sample2.png') center/contain no-repeat;
    opacity: 0.05;
    z-index: 0;
  }

  h2 {
    color: var(--primary-color);
    font-size: 1.8rem;
    margin-top: 40px;
    position: relative;
    padding-bottom: 15px;
  }

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

  h3 {
    color: var(--secondary-color);
    font-size: 1.4rem;
    margin-top: 30px;
  }

  p {
    font-size: 1.05rem;
    margin-bottom: 20px;
    position: relative;
    z-index: 1;
  }

  pre {
    background: #2d2d2d;
    color: #f8f8f2;
    padding: 20px;
    border-radius: 8px;
    overflow-x: auto;
    font-size: 0.9rem;
    margin: 25px 0;
    box-shadow: 0 4px 6px rgba(0,0,0,0.1);
    position: relative;
  }

  pre::before {
    content: 'CSS';
    position: absolute;
    top: 0;
    left: 0;
    background: var(--accent-color-1);
    color: white;
    padding: 2px 10px;
    border-radius: 0 0 5px 0;
    font-size: 0.8rem;
  }

  .sidebar {
    background: white;
    border-radius: 15px;
    padding: 25px;
    box-shadow: var(--card-shadow);
    align-self: start;
    position: sticky;
    top: 20px;
  }

  .sidebar-title {
    color: var(--secondary-color);
    font-size: 1.2rem;
    margin-bottom: 20px;
    padding-bottom: 10px;
    border-bottom: 1px solid #eee;
  }

  .nav-links {
    list-style: none;
    padding: 0;
    margin: 0;
  }

  .nav-links li {
    margin-bottom: 10px;
  }

  .nav-links a {
    display: block;
    padding: 10px 15px;
    color: var(--text-color);
    text-decoration: none;
    border-radius: 6px;
    transition: var(--transition);
    position: relative;
  }

  .nav-links a:hover {
    background: rgba(58, 123, 213, 0.1);
    color: var(--primary-color);
    transform: translateX(5px);
  }

  .nav-links a::before {
    content: '';
    position: absolute;
    left: 0;
    top: 0;
    height: 100%;
    width: 3px;
    background: var(--primary-color);
    opacity: 0;
    transition: var(--transition);
  }

  .nav-links a:hover::before {
    opacity: 1;
  }

  .image-gallery {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(150px, 1fr));
    gap: 20px;
    margin: 40px 0;
  }

  .gallery-item {
    border-radius: 10px;
    overflow: hidden;
    box-shadow: 0 5px 15px rgba(0,0,0,0.1);
    transition: var(--transition);
    aspect-ratio: 1/1;
  }

  .gallery-item:hover {
    transform: translateY(-5px);
    box-shadow: 0 15px 30px rgba(0,0,0,0.2);
  }

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

  .gallery-item:hover img {
    transform: scale(1.05);
  }

  .footer {
    background: linear-gradient(45deg, var(--secondary-color), var(--primary-color));
    color: white;
    padding: 40px 0;
    text-align: center;
    border-radius: 20px 20px 0 0;
    margin-top: 80px;
  }

  .footer p {
    max-width: 800px;
    margin: 0 auto;
    opacity: 0.8;
  }

  @keyframes float {
    0%, 100% { transform: translateY(0); }
    50% { transform: translateY(-10px); }
  }

  .floating {
    animation: float 3s ease-in-out infinite;
  }

  @media (max-width: 768px) {
    .header {
      padding: 30px 0;
    }
    
    h1 {
      font-size: 2rem;
    }
    
    article {
      padding: 25px;
    }
    
    .image-gallery {
      grid-template-columns: repeat(auto-fill, minmax(120px, 1fr));
    }
  }