:root {
    --primary-dark-blue: #0A214B;
    --primary-electric-blue: #1E90FF;
    --accent-orange: #FFA500;
    --accent-green: #32CD32;
    --dark-gray: #1A1A1A;
    --light-gray: #F5F5F5;
    --transition: all 0.3s cubic-bezier(0.25, 0.8, 0.25, 1);
  }

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

  body {
    font-family: 'Montserrat', 'Open Sans', sans-serif;
    line-height: 1.6;
    color: #333;
    background-color: var(--light-gray);
    overflow-x: hidden;
  }

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

  /* Header Styles */
  .header {
    background: linear-gradient(135deg, var(--primary-dark-blue) 0%, var(--primary-electric-blue) 100%);
    color: white;
    padding: 2rem 0;
    clip-path: polygon(0 0, 100% 0, 100% 85%, 0% 100%);
    margin-bottom: 3rem;
    position: relative;
    overflow: hidden;
  }

  .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;
    padding: 3rem 0;
  }

  .header h1 {
    font-size: 2.5rem;
    margin-bottom: 1rem;
    text-shadow: 0 2px 4px rgba(0,0,0,0.3);
  }

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

  .notice {
    background-color: rgba(255,255,255,0.2);
    padding: 1rem;
    border-radius: 5px;
    display: inline-block;
    margin-top: 2rem;
    font-size: 0.9rem;
  }

  /* Navigation */
  .navbar {
    position: sticky;
    top: 0;
    background-color: var(--primary-dark-blue);
    padding: 1rem 0;
    z-index: 1000;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
  }

  .nav-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
  }

  .nav-logo {
    color: white;
    font-weight: bold;
    font-size: 1.2rem;
    text-decoration: none;
  }

  .nav-menu {
    display: flex;
    list-style: none;
  }

  .nav-item {
    margin-left: 2rem;
  }

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

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

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

  /* Main Content */
  .main-content {
    display: grid;
    grid-template-columns: 1fr 3fr;
    gap: 2rem;
    margin-bottom: 3rem;
  }

  @media (max-width: 768px) {
    .main-content {
      grid-template-columns: 1fr;
    }
  }

  /* Sidebar */
  .sidebar {
    background-color: white;
    border-radius: 10px;
    padding: 2rem;
    box-shadow: 0 5px 15px rgba(0,0,0,0.1);
    position: sticky;
    top: 80px;
    height: fit-content;
  }

  .sidebar-title {
    font-size: 1.2rem;
    margin-bottom: 1.5rem;
    color: var(--primary-dark-blue);
    position: relative;
    padding-bottom: 0.5rem;
  }

  .sidebar-title::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 50px;
    height: 3px;
    background-color: var(--accent-orange);
  }

  .sidebar-nav {
    list-style: none;
  }

  .sidebar-item {
    margin-bottom: 1rem;
  }

  .sidebar-link {
    color: var(--dark-gray);
    text-decoration: none;
    transition: var(--transition);
    display: block;
    padding: 0.5rem 0;
  }

  .sidebar-link:hover {
    color: var(--primary-electric-blue);
    transform: translateX(5px);
  }

  /* Article */
  article {
    background-color: white;
    border-radius: 10px;
    padding: 3rem;
    box-shadow: 0 5px 15px rgba(0,0,0,0.1);
  }

  article h2 {
    color: var(--primary-dark-blue);
    margin-bottom: 1.5rem;
    font-size: 1.8rem;
    position: relative;
    padding-bottom: 0.5rem;
  }

  article h2::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 80px;
    height: 3px;
    background-color: var(--accent-orange);
  }

  article h3 {
    color: var(--primary-dark-blue);
    margin: 2rem 0 1rem;
    font-size: 1.4rem;
  }

  article p {
    margin-bottom: 1.5rem;
    font-size: 1.1rem;
    line-height: 1.7;
  }

  article strong {
    color: var(--primary-electric-blue);
  }

  /* Code Blocks */
  pre {
    background-color: #1E1E1E;
    border-radius: 8px;
    padding: 1.5rem;
    margin: 1.5rem 0;
    overflow: auto;
    position: relative;
  }

  pre::before {
    content: 'CSS';
    position: absolute;
    top: 0;
    right: 0;
    background-color: var(--accent-orange);
    color: white;
    padding: 0.3rem 0.8rem;
    border-radius: 0 0 0 8px;
    font-size: 0.8rem;
    font-weight: bold;
  }

  code {
    font-family: 'Courier New', monospace;
    color: #D4D4D4;
    font-size: 0.9rem;
  }

  /* Tables */
  table {
    width: 100%;
    border-collapse: collapse;
    margin: 2rem 0;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
  }

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

  th {
    background-color: var(--primary-dark-blue);
    color: white;
  }

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

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

  /* Image Gallery */
  .image-gallery {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 1.5rem;
    margin: 2rem 0;
  }

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

  .gallery-item:hover {
    transform: translateY(-5px);
    box-shadow: 0 10px 25px rgba(0,0,0,0.2);
  }

  .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: 2rem;
    margin: 2rem 0;
  }

  .card {
    background-color: white;
    border-radius: 10px;
    padding: 2rem;
    box-shadow: 0 5px 15px rgba(0,0,0,0.1);
    transition: var(--transition);
    border-top: 4px solid var(--primary-electric-blue);
  }

  .card:hover {
    transform: translateY(-10px);
    box-shadow: 0 15px 30px rgba(0,0,0,0.2);
  }

  .card h4 {
    color: var(--primary-dark-blue);
    margin-bottom: 1rem;
    font-size: 1.2rem;
  }

  .card p {
    font-size: 1rem;
    color: #666;
  }

  /* Footer */
  .footer {
    background: linear-gradient(135deg, var(--primary-dark-blue) 0%, #142938 100%);
    color: white;
    padding: 3rem 0;
    margin-top: 3rem;
    clip-path: polygon(0 15%, 100% 0, 100% 100%, 0% 100%);
  }

  .footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
  }

  .footer-section h3 {
    font-size: 1.2rem;
    margin-bottom: 1.5rem;
    position: relative;
    padding-bottom: 0.5rem;
  }

  .footer-section h3::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 50px;
    height: 2px;
    background-color: var(--accent-orange);
  }

  .footer-section p {
    margin-bottom: 1rem;
    opacity: 0.8;
  }

  .footer-bottom {
    text-align: center;
    padding-top: 2rem;
    margin-top: 2rem;
    border-top: 1px solid rgba(255,255,255,0.1);
    font-size: 0.9rem;
    opacity: 0.7;
  }

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

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

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

    .header p {
      font-size: 1rem;
    }

    .nav-menu {
      display: none;
    }

    article {
      padding: 2rem 1.5rem;
    }

    pre {
      padding: 1rem;
    }
  }

  /* Additional Styles */
  .divider {
    height: 1px;
    background: linear-gradient(to right, transparent, var(--primary-electric-blue), transparent);
    margin: 2rem 0;
  }

  .highlight {
    background-color: rgba(30, 144, 255, 0.1);
    padding: 0.2rem 0.4rem;
    border-radius: 3px;
    color: var(--primary-electric-blue);
  }

  .btn {
    display: inline-block;
    background-color: var(--accent-orange);
    color: white;
    padding: 0.8rem 1.5rem;
    border-radius: 5px;
    text-decoration: none;
    font-weight: bold;
    transition: var(--transition);
    border: none;
    cursor: pointer;
  }

  .btn:hover {
    background-color: #e69500;
    transform: translateY(-3px);
    box-shadow: 0 5px 15px rgba(255, 165, 0, 0.3);
  }