:root {
    --primary-color: #0074D9;
    --accent-color: #FF851B;
    --background-color: #F5F5F5;
    --secondary-color: #6c757d;
    --highlight-color: #28a745;
    --dark-color: #343a40;
    --light-color: #f8f9fa;
    --gradient-primary: linear-gradient(135deg, var(--primary-color), var(--accent-color);
    --gradient-secondary: linear-gradient(45deg, var(--accent-color), #ff4136);
    --font-main: 'Roboto', sans-serif;
    --font-heading: 'Montserrat', sans-serif;
    --shadow-sm: 0 4px 6px rgba(0,0,0,0.1);
    --shadow-md: 0 8px 16px rgba(0,0,0,0.1);
    --shadow-lg: 0 12px 24px rgba(0,0,0,0.2);
    --transition: all 0.3s ease;
  }

  @import url('https://fonts.googleapis.com/css2?family=Montserrat:wght@500;700&family=Roboto:wght@300;400;500&display=swap');

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

  body {
    font-family: var(--font-main);
    background-color: var(--background-color);
    color: var(--dark-color);
    line-height: 1.6;
    overflow-x: hidden;
  }

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

  /* Header Styles */
  .header {
    background: var(--gradient-primary);
    color: white;
    padding: 2rem 0;
    text-align: center;
    position: relative;
    overflow: hidden;
    margin-bottom: 3rem;
    border-radius: 0 0 20px 20px;
    box-shadow: var(--shadow-md);
  }

  .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 right;
    opacity: 0.1;
    z-index: 0;
  }

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

  .header h1 {
    font-family: var(--font-heading);
    font-size: 2.5rem;
    margin-bottom: 1rem;
    text-shadow: 0 2px 4px rgba(0,0,0,0.2);
  }

  .header p {
    font-size: 1.2rem;
    margin-bottom: 1.5rem;
  }

  .notice {
    background-color: rgba(255,255,255,0.2);
    padding: 10px 20px;
    border-radius: 50px;
    display: inline-block;
    margin-top: 1rem;
    font-size: 0.9rem;
    backdrop-filter: blur(5px);
  }

  /* Navigation */
  .nav-container {
    background-color: white;
    box-shadow: var(--shadow-sm);
    position: sticky;
    top: 0;
    z-index: 1000;
  }

  .nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 0;
  }

  .nav-logo {
    font-family: var(--font-heading);
    font-weight: 700;
    color: var(--primary-color);
    font-size: 1.5rem;
    text-decoration: none;
  }

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

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

  .nav-link {
    color: var(--dark-color);
    text-decoration: none;
    font-weight: 500;
    transition: var(--transition);
    position: relative;
    padding: 0.5rem 0;
  }

  .nav-link:hover {
    color: var(--primary-color);
  }

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

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

  /* Article Styles */
  .article-container {
    display: grid;
    grid-template-columns: 1fr 300px;
    gap: 2rem;
    margin: 3rem 0;
  }

  @media (max-width: 992px) {
    .article-container {
      grid-template-columns: 1fr;
    }
  }

  article {
    background-color: white;
    padding: 2rem;
    border-radius: 12px;
    box-shadow: var(--shadow-sm);
  }

  article h2 {
    font-family: var(--font-heading);
    color: var(--primary-color);
    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: 60px;
    height: 3px;
    background: var(--gradient-primary);
    border-radius: 3px;
  }

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

  article p {
    margin-bottom: 1.5rem;
    font-size: 1.05rem;
    line-height: 1.7;
  }

  article img {
    max-width: 100%;
    height: auto;
    border-radius: 8px;
    margin: 1.5rem 0;
    box-shadow: var(--shadow-md);
    transition: var(--transition);
  }

  article img:hover {
    transform: scale(1.02);
    box-shadow: var(--shadow-lg);
  }

  /* Code Blocks */
  pre {
    background-color: #282c34;
    color: #abb2bf;
    padding: 1.5rem;
    border-radius: 8px;
    overflow-x: auto;
    margin: 1.5rem 0;
    box-shadow: var(--shadow-md);
    position: relative;
  }

  pre::before {
    content: "CSS";
    position: absolute;
    top: 0;
    left: 0;
    background-color: var(--accent-color);
    color: white;
    padding: 0.2rem 0.8rem;
    font-size: 0.8rem;
    border-radius: 0 0 8px 0;
  }

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

  /* Sidebar */
  .sidebar {
    position: sticky;
    top: 100px;
    align-self: start;
  }

  .sidebar-card {
    background-color: white;
    border-radius: 12px;
    box-shadow: var(--shadow-sm);
    padding: 1.5rem;
    margin-bottom: 2rem;
    transition: var(--transition);
  }

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

  .sidebar-title {
    font-family: var(--font-heading);
    color: var(--primary-color);
    margin-bottom: 1rem;
    font-size: 1.2rem;
    display: flex;
    align-items: center;
  }

  .sidebar-title svg {
    margin-right: 0.5rem;
    color: var(--accent-color);
  }

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

  .sidebar-item {
    margin-bottom: 0.8rem;
    position: relative;
    padding-left: 1.5rem;
  }

  .sidebar-item::before {
    content: "";
    position: absolute;
    left: 0;
    top: 0.7rem;
    width: 8px;
    height: 8px;
    background-color: var(--accent-color);
    border-radius: 50%;
  }

  .sidebar-link {
    color: var(--dark-color);
    text-decoration: none;
    transition: var(--transition);
  }

  .sidebar-link:hover {
    color: var(--primary-color);
  }

  /* Gallery */
  .gallery {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(150px, 1fr));
    gap: 1rem;
    margin: 2rem 0;
  }

  .gallery-item {
    border-radius: 8px;
    overflow: hidden;
    box-shadow: var(--shadow-sm);
    transition: var(--transition);
    aspect-ratio: 1/1;
  }

  .gallery-item:hover {
    transform: scale(1.05);
    box-shadow: var(--shadow-lg);
    z-index: 1;
  }

  .gallery-item img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    display: block;
  }

  /* Footer */
  .footer {
    background: var(--gradient-primary);
    color: white;
    padding: 3rem 0;
    margin-top: 3rem;
    text-align: center;
  }

  .footer-content {
    max-width: 800px;
    margin: 0 auto;
  }

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

  .footer-links {
    display: flex;
    justify-content: center;
    list-style: none;
    margin: 1.5rem 0;
  }

  .footer-link {
    color: white;
    text-decoration: none;
    margin: 0 1rem;
    transition: var(--transition);
  }

  .footer-link:hover {
    color: var(--accent-color);
  }

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

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

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

    .nav-menu {
      display: none;
    }

    .nav-toggle {
      display: block;
    }

    .gallery {
      grid-template-columns: repeat(2, 1fr);
    }
  }

  /* Utility Classes */
  .text-primary {
    color: var(--primary-color);
  }

  .text-accent {
    color: var(--accent-color);
  }

  .bg-primary {
    background-color: var(--primary-color);
  }

  .bg-accent {
    background-color: var(--accent-color);
  }

  .rounded {
    border-radius: 8px;
  }

  .shadow {
    box-shadow: var(--shadow-sm);
  }

  .transition {
    transition: var(--transition);
  }