:root {
    --primary-dark: #0073D9;
    --primary-light: #4567B7;
    --accent: #8A2BE2;
    --alert-success: #32CD32;
    --alert-warning: #FFA500;
    --text-dark: #333;
    --text-light: #555;
    --bg-light: #F5F5F5;
    --white: #ffffff;
    --shadow-sm: 0 4px 6px rgba(0, 0, 0, 0.1);
    --shadow-md: 0 10px 15px rgba(0, 0, 0, 0.2);
    --transition: all 0.3s ease;
  }

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

  body {
    font-family: 'Roboto', sans-serif;
    font-size: 16px;
    line-height: 1.6;
    color: var(--text-light);
    background: radial-gradient(circle at 10% 20%, rgba(245, 245, 245, 0.9) 0%, rgba(235, 235, 235, 0.9) 90%);
    min-height: 100%;
    overflow-x: hidden;
  }

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

  /* Header Styles */
  .header {
    background: linear-gradient(135deg, var(--primary-dark), var(--primary-light));
    color: var(--white);
    padding: 2rem 0;
    position: relative;
    overflow: hidden;
    box-shadow: var(--shadow-sm);
  }

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

  .header-content {
    position: relative;
    z-index: 1;
    text-align: center;
  }

  .header h1 {
    font-family: 'Helvetica Neue', sans-serif;
    font-weight: bold;
    font-size: 2.5rem;
    margin-bottom: 1rem;
    text-shadow: 0 2px 4px rgba(0, 0, 0, 0.2);
  }

  .header p {
    font-size: 1.2rem;
    max-width: 800px;
    margin: 0 auto 2rem;
  }

  .notice {
    background-color: rgba(255, 255, 255, 0.2);
    padding: 10px 20px;
    border-radius: 5px;
    display: inline-block;
    margin-top: 1rem;
    backdrop-filter: blur(5px);
  }

  /* Navigation */
  .nav-tabs {
    display: flex;
    justify-content: center;
    background-color: var(--white);
    border-bottom: 1px solid #ddd;
    position: sticky;
    top: 0;
    z-index: 100;
    box-shadow: var(--shadow-sm);
  }

  .nav-tabs .tab {
    padding: 15px 25px;
    cursor: pointer;
    transition: var(--transition);
    font-weight: 500;
    position: relative;
  }

  .nav-tabs .tab:hover {
    background-color: rgba(0, 0, 0, 0.05);
  }

  .nav-tabs .active {
    color: var(--accent);
  }

  .nav-tabs .active::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 20%;
    width: 60%;
    height: 3px;
    background-color: var(--accent);
    border-radius: 3px 3px 0 0;
  }

  /* Main Content */
  .main-content {
    padding: 3rem 0;
  }

  article {
    background-color: var(--white);
    border-radius: 10px;
    box-shadow: var(--shadow-sm);
    padding: 2.5rem;
    margin-bottom: 3rem;
  }

  article h2 {
    font-family: 'Helvetica Neue', sans-serif;
    font-weight: bold;
    color: var(--text-dark);
    font-size: 1.8rem;
    margin-bottom: 1.5rem;
    position: relative;
    padding-bottom: 0.5rem;
  }

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

  article h3 {
    font-family: 'Helvetica Neue', sans-serif;
    font-weight: bold;
    color: var(--text-dark);
    font-size: 1.4rem;
    margin: 2rem 0 1rem;
  }

  article p {
    margin-bottom: 1.5rem;
    line-height: 1.7;
  }

  article span.highlight {
    font-weight: bold;
    color: var(--accent);
  }

  /* Code Blocks */
  pre {
    background: linear-gradient(135deg, #2c3e50, #1a1a2e);
    border-radius: 8px;
    padding: 1.5rem;
    margin: 1.5rem 0;
    overflow: auto;
    box-shadow: var(--shadow-md);
  }

  code {
    font-family: 'Courier New', monospace;
    color: #f8f8f2;
    font-size: 0.9rem;
    line-height: 1.5;
  }

  .language-css {
    color: #66d9ef;
  }

  /* Image Gallery */
  .image-gallery {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 20px;
    margin: 2rem 0;
  }

  .gallery-item {
    border-radius: 10px;
    overflow: hidden;
    box-shadow: var(--shadow-sm);
    transition: var(--transition);
    position: relative;
  }

  .gallery-item:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-md);
  }

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

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

  /* Cards */
  .card-container {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 30px;
    margin: 3rem 0;
  }

  .card {
    background-color: var(--white);
    border-radius: 10px;
    box-shadow: var(--shadow-sm);
    padding: 2rem;
    transition: var(--transition);
    position: relative;
    overflow: hidden;
  }

  .card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 5px;
    height: 100%;
    background: linear-gradient(to bottom, var(--primary-dark), var(--accent));
  }

  .card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-md);
  }

  .card h4 {
    font-family: 'Helvetica Neue', sans-serif;
    font-weight: bold;
    color: var(--text-dark);
    margin-bottom: 1rem;
    font-size: 1.2rem;
  }

  .card p {
    margin-bottom: 1.5rem;
  }

  /* Footer */
  .footer {
    background: linear-gradient(135deg, var(--primary-dark), var(--primary-light));
    color: var(--white);
    padding: 3rem 0;
    text-align: center;
    position: relative;
  }

  .footer::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: url('https://images.gptkong.com/demo/sample12.png') no-repeat;
    background-size: cover;
    opacity: 0.1;
    z-index: 0;
  }

  .footer-content {
    position: relative;
    z-index: 1;
  }

  .footer p {
    margin-bottom: 1rem;
  }

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

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

  /* Responsive */
  @media (max-width: 768px) {
    .header h1 {
      font-size: 2rem;
    }

    .nav-tabs {
      flex-wrap: wrap;
    }

    .nav-tabs .tab {
      padding: 12px 15px;
      font-size: 0.9rem;
    }

    article {
      padding: 1.5rem;
    }

    .card-container {
      grid-template-columns: 1fr;
    }
  }