:root {
    --primary: #0047AB;
    --secondary: #34C759;
    --accent: #FFA500;
    --light: #FFFFFF;
    --dark: #333333;
    --gray: #F5F5F5;
    --shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
    --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-color: var(--gray);
    color: var(--dark);
    line-height: 1.6;
    font-size: 16px;
    overflow-x: hidden;
  }

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

  /* Header */
  .header {
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    color: var(--light);
    padding: 40px 0;
    text-align: center;
    position: relative;
    overflow: hidden;
    margin-bottom: 40px;
  }

  .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;
  }

  .header h1 {
    font-size: 2.5rem;
    margin-bottom: 10px;
    position: relative;
    z-index: 1;
    text-shadow: 0 2px 4px rgba(0, 0, 0, 0.2);
  }

  .header p {
    font-size: 1.2rem;
    max-width: 800px;
    margin: 0 auto;
    position: relative;
    z-index: 1;
    opacity: 0.9;
  }

  /* Navigation */
  .navbar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 20px 0;
    background-color: var(--light);
    box-shadow: var(--shadow);
    position: sticky;
    top: 0;
    z-index: 100;
  }

  .navbar .logo {
    font-size: 1.5rem;
    font-weight: bold;
    color: var(--primary);
    display: flex;
    align-items: center;
    gap: 10px;
  }

  .navbar .logo img {
    width: 40px;
    height: 40px;
    border-radius: 50%;
    object-fit: cover;
  }

  .navbar .menu {
    display: flex;
    gap: 30px;
  }

  .navbar .menu a {
    text-decoration: none;
    color: var(--dark);
    font-weight: 500;
    transition: var(--transition);
    position: relative;
  }

  .navbar .menu a:hover {
    color: var(--primary);
  }

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

  .navbar .menu a:hover::after {
    width: 100%;
  }

  /* Main Content */
  .main-content {
    display: grid;
    grid-template-columns: 1fr 300px;
    gap: 40px;
    margin: 40px 0;
  }

  article {
    background-color: var(--light);
    padding: 40px;
    border-radius: 12px;
    box-shadow: var(--shadow);
  }

  article h2 {
    color: var(--primary);
    margin-bottom: 20px;
    font-size: 1.8rem;
    position: relative;
    padding-bottom: 10px;
  }

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

  article h3 {
    color: var(--secondary);
    margin: 30px 0 15px;
    font-size: 1.4rem;
  }

  article p {
    margin-bottom: 20px;
    line-height: 1.7;
  }

  article img {
    max-width: 100%;
    height: auto;
    border-radius: 8px;
    margin: 20px 0;
    box-shadow: var(--shadow);
    transition: var(--transition);
  }

  article img:hover {
    transform: translateY(-5px);
  }

  /* Code Blocks */
  pre {
    background-color: #282c34;
    color: #abb2bf;
    padding: 20px;
    border-radius: 8px;
    overflow-x: auto;
    margin: 20px 0;
    font-size: 14px;
    line-height: 1.5;
    position: relative;
  }

  pre::before {
    content: 'CSS';
    position: absolute;
    top: 0;
    left: 0;
    background-color: var(--accent);
    color: var(--light);
    padding: 2px 10px;
    border-radius: 0 0 4px 0;
    font-size: 12px;
    font-weight: bold;
  }

  code {
    font-family: 'Courier New', Courier, monospace;
  }

  /* Tables */
  table {
    width: 100%;
    border-collapse: collapse;
    margin: 20px 0;
    box-shadow: var(--shadow);
    border-radius: 8px;
    overflow: hidden;
  }

  th, td {
    padding: 15px;
    text-align: left;
    border-bottom: 1px solid #eee;
  }

  th {
    background-color: var(--primary);
    color: var(--light);
    font-weight: 500;
  }

  tr:nth-child(even) {
    background-color: #f9f9f9;
  }

  tr:hover {
    background-color: #f1f1f1;
  }

  /* Sidebar */
  .sidebar {
    background-color: var(--light);
    padding: 30px;
    border-radius: 12px;
    box-shadow: var(--shadow);
    height: fit-content;
    position: sticky;
    top: 100px;
  }

  .sidebar h3 {
    color: var(--primary);
    margin-bottom: 20px;
    font-size: 1.3rem;
    position: relative;
    padding-bottom: 10px;
  }

  .sidebar h3::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 40px;
    height: 2px;
    background: linear-gradient(90deg, var(--primary), var(--secondary));
  }

  .sidebar .gallery {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 15px;
    margin-top: 20px;
  }

  .sidebar .gallery img {
    width: 100%;
    height: 120px;
    object-fit: cover;
    border-radius: 8px;
    box-shadow: var(--shadow);
    transition: var(--transition);
    cursor: pointer;
  }

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

  /* Footer */
  .footer {
    background: linear-gradient(135deg, var(--primary), var(--secondary));
    color: var(--light);
    padding: 40px 0;
    text-align: center;
    margin-top: 60px;
  }

  .footer p {
    opacity: 0.8;
    margin-top: 20px;
  }

  /* Responsive */
  @media (max-width: 992px) {
    .main-content {
      grid-template-columns: 1fr;
    }

    .sidebar {
      position: static;
      margin-top: 40px;
    }
  }

  @media (max-width: 768px) {
    .navbar {
      flex-direction: column;
      gap: 20px;
      padding: 20px;
    }

    .navbar .menu {
      flex-direction: column;
      gap: 15px;
      text-align: center;
    }

    article {
      padding: 30px 20px;
    }

    .header h1 {
      font-size: 2rem;
    }
  }

  /* Animations */
  @keyframes fadeIn {
    from { opacity: 0; transform: translateY(20px); }
    to { opacity: 1; transform: translateY(0); }
  }

  .fade-in {
    animation: fadeIn 0.6s ease-out forwards;
  }

  .delay-1 { animation-delay: 0.2s; }
  .delay-2 { animation-delay: 0.4s; }
  .delay-3 { animation-delay: 0.6s; }

  /* Special Notice */
  .notice {
    background-color: var(--light);
    padding: 20px;
    border-radius: 8px;
    box-shadow: var(--shadow);
    margin: 40px 0;
    border-left: 4px solid var(--accent);
    display: flex;
    align-items: center;
    gap: 15px;
  }

  .notice-icon {
    font-size: 24px;
    color: var(--accent);
  }

  .notice p {
    margin: 0;
    font-weight: 500;
  }