:root {
    --primary: #1A237E;
    --secondary: #2196F3;
    --accent: #FFC107;
    --text: #333333;
    --light: #F5F5F5;
    --white: #FFFFFF;
    --dark: #0A0F3D;
    --radius: 12px;
    --shadow: 0 8px 24px rgba(0, 0, 0, 0.1);
    --transition: all 0.3s cubic-bezier(0.25, 0.8, 0.25, 1);
  }

  @font-face {
    font-family: 'Montserrat';
    src: local('Montserrat'), url(https://fonts.gstatic.com/s/montserrat/v15/JTUSjIg1_i6t8kCHKm459Wlhyw.woff2) format('woff2');
  }

  @font-face {
    font-family: 'Open Sans';
    src: local('Open Sans'), url(https://fonts.gstatic.com/s/opensans/v18/mem8YaGs126MiZpBA-UFVZ0e.woff2) format('woff2');
  }

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

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

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

  /* Header Styles */
  .header {
    background: linear-gradient(135deg, var(--primary), var(--dark));
    color: var(--white);
    padding: 60px 0;
    text-align: center;
    position: relative;
    overflow: hidden;
    margin-bottom: 60px;
  }

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

  .header h1 {
    font-family: 'Montserrat', sans-serif;
    font-size: 2.8rem;
    margin-bottom: 20px;
    text-shadow: 0 2px 4px rgba(0, 0, 0, 0.3);
  }

  .header p {
    font-size: 1.2rem;
    opacity: 0.9;
    margin-bottom: 30px;
  }

  .notice {
    background: rgba(255, 255, 255, 0.2);
    padding: 15px;
    border-radius: var(--radius);
    margin-top: 30px;
    font-size: 0.9rem;
    display: inline-block;
  }

  /* Navigation */
  .navbar {
    position: sticky;
    top: 0;
    width: 100%;
    background: rgba(26, 35, 126, 0.95);
    backdrop-filter: blur(10px);
    display: flex;
    justify-content: center;
    padding: 15px 0;
    z-index: 1000;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
  }

  .nav-container {
    display: flex;
    justify-content: space-between;
    width: 100%;
    max-width: 1200px;
    padding: 0 20px;
  }

  .nav-links {
    display: flex;
    gap: 20px;
  }

  .navbar a {
    color: var(--white);
    text-decoration: none;
    padding: 8px 16px;
    transition: var(--transition);
    font-family: 'Montserrat', sans-serif;
    font-weight: 500;
    border-radius: var(--radius);
    position: relative;
  }

  .navbar a:hover {
    background: rgba(255, 255, 255, 0.1);
    color: var(--accent);
  }

  .navbar a::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 50%;
    transform: translateX(-50%);
    width: 0;
    height: 2px;
    background: var(--accent);
    transition: var(--transition);
  }

  .navbar a:hover::after {
    width: 70%;
  }

  /* Article Styles */
  .article-container {
    display: grid;
    grid-template-columns: 1fr 300px;
    gap: 40px;
    padding: 40px 0;
  }

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

  article h2 {
    font-family: 'Montserrat', sans-serif;
    color: var(--primary);
    font-size: 1.8rem;
    margin-bottom: 25px;
    position: relative;
    padding-bottom: 15px;
  }

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

  article h3 {
    font-family: 'Montserrat', sans-serif;
    color: var(--primary);
    font-size: 1.4rem;
    margin: 30px 0 15px;
  }

  article p {
    margin-bottom: 20px;
    font-size: 1.05rem;
  }

  article span {
    color: var(--secondary);
    font-weight: 600;
  }

  /* Code Blocks */
  pre {
    background: #282c34;
    border-radius: var(--radius);
    padding: 20px;
    margin: 25px 0;
    overflow: auto;
    position: relative;
  }

  pre::before {
    content: 'CSS';
    position: absolute;
    top: 0;
    right: 0;
    background: var(--secondary);
    color: var(--white);
    padding: 5px 15px;
    border-radius: 0 var(--radius) 0 var(--radius);
    font-family: 'Montserrat', sans-serif;
    font-size: 0.8rem;
  }

  code {
    font-family: 'Courier New', monospace;
    color: #abb2bf;
    font-size: 0.95rem;
    line-height: 1.5;
  }

  /* Sidebar */
  .sidebar {
    position: sticky;
    top: 100px;
    height: fit-content;
  }

  .sidebar-card {
    background: var(--white);
    border-radius: var(--radius);
    padding: 25px;
    margin-bottom: 30px;
    box-shadow: var(--shadow);
  }

  .sidebar-card h3 {
    font-family: 'Montserrat', sans-serif;
    color: var(--primary);
    margin-bottom: 20px;
    font-size: 1.2rem;
    position: relative;
    padding-bottom: 10px;
  }

  .sidebar-card h3::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 40px;
    height: 2px;
    background: var(--accent);
  }

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

  .image-grid img {
    width: 100%;
    border-radius: var(--radius);
    transition: var(--transition);
    box-shadow: 0 4px 8px rgba(0, 0, 0, 0.1);
  }

  .image-grid img:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 16px rgba(0, 0, 0, 0.15);
  }

  /* Footer */
  .footer {
    background: linear-gradient(135deg, var(--primary), var(--dark));
    color: var(--white);
    padding: 60px 0 30px;
    margin-top: 60px;
    text-align: center;
  }

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

  .footer p {
    opacity: 0.8;
    margin-bottom: 30px;
  }

  .footer-links {
    display: flex;
    justify-content: center;
    gap: 30px;
    margin-bottom: 40px;
  }

  .footer a {
    color: var(--white);
    text-decoration: none;
    transition: var(--transition);
    position: relative;
  }

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

  .footer a::after {
    content: '';
    position: absolute;
    bottom: -5px;
    left: 0;
    width: 0;
    height: 1px;
    background: var(--accent);
    transition: var(--transition);
  }

  .footer a:hover::after {
    width: 100%;
  }

  .copyright {
    font-size: 0.9rem;
    opacity: 0.6;
    margin-top: 30px;
  }

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

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

    .image-grid {
      grid-template-columns: repeat(3, 1fr);
    }
  }

  @media (max-width: 768px) {
    .header h1 {
      font-size: 2.2rem;
    }

    .nav-links {
      gap: 10px;
    }

    .navbar a {
      padding: 8px 12px;
      font-size: 0.9rem;
    }

    article {
      padding: 30px;
    }

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

  @media (max-width: 576px) {
    .header {
      padding: 40px 0;
    }

    .header h1 {
      font-size: 1.8rem;
    }

    .nav-container {
      flex-direction: column;
      align-items: center;
      gap: 10px;
    }

    .nav-links {
      flex-wrap: wrap;
      justify-content: center;
    }

    article {
      padding: 25px 20px;
    }

    .image-grid {
      grid-template-columns: 1fr;
    }
  }

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

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

  /* Particles */
  .particles {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: 0;
    overflow: hidden;
  }

  .particle {
    position: absolute;
    background: rgba(255, 255, 255, 0.5);
    border-radius: 50%;
    pointer-events: none;
  }

  /* Utility Classes */
  .mt-1 { margin-top: 10px; }
  .mt-2 { margin-top: 20px; }
  .mt-3 { margin-top: 30px; }
  .mt-4 { margin-top: 40px; }
  .mb-1 { margin-bottom: 10px; }
  .mb-2 { margin-bottom: 20px; }
  .mb-3 { margin-bottom: 30px; }
  .mb-4 { margin-bottom: 40px; }