:root {
    --primary-color: #1e3c72;
    --secondary-color: #2a5298;
    --accent-color: #4a90e2;
    --text-color: #ffffff;
    --card-bg: rgba(255, 255, 255, 0.1);
    --transition: all 0.3s ease;
  }

  @font-face {
    font-family: 'Roboto';
    src: local('Roboto'), local('Roboto-Regular');
    font-display: swap;
  }

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

  body {
    font-family: 'Roboto', sans-serif;
    color: var(--text-color);
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    line-height: 1.6;
    padding-top: 80px;
    min-height: 100%;
  }

  .design-notice {
    position: fixed;
    bottom: 20px;
    right: 20px;
    background: rgba(0,0,0,0.7);
    padding: 10px 15px;
    border-radius: 20px;
    font-size: 14px;
    z-index: 1000;
    backdrop-filter: blur(5px);
  }

  .navbar {
    position: fixed;
    top: 0;
    width: 100%;
    background: rgba(30, 60, 114, 0.8);
    backdrop-filter: blur(5px);
    padding: 15px 30px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    z-index: 1000;
    box-shadow: 0 2px 10px rgba(0,0,0,0.2);
  }

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

  .nav-links a {
    color: var(--text-color);
    text-decoration: none;
    transition: var(--transition);
    padding: 5px 10px;
    border-radius: 5px;
  }

  .nav-links a:hover {
    background: rgba(255,255,255,0.1);
  }

  .sidebar {
    position: fixed;
    left: 0;
    top: 80px;
    width: 250px;
    height: calc(100vh - 80px);
    background: rgba(30, 60, 114, 0.9);
    backdrop-filter: blur(5px);
    padding: 30px 20px;
    transform: translateX(-100%);
    transition: var(--transition);
    z-index: 999;
  }

  .sidebar.active {
    transform: translateX(0);
  }

  .sidebar a {
    display: block;
    color: var(--text-color);
    margin: 15px 0;
    text-decoration: none;
    transition: var(--transition);
    padding: 8px 15px;
    border-radius: 5px;
  }

  .sidebar a:hover {
    background: rgba(255,255,255,0.1);
  }

  .menu-toggle {
    display: none;
    background: none;
    border: none;
    color: var(--text-color);
    font-size: 24px;
    cursor: pointer;
  }

  .main-content {
    max-width: 1200px;
    margin: 0 auto;
    padding: 30px;
    position: relative;
  }

  .hero {
    text-align: center;
    padding: 60px 20px;
    margin-bottom: 50px;
    position: relative;
    overflow: hidden;
    border-radius: 15px;
  }

  .hero::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: url('https://images.gptkong.com/demo/sample1.png') center/cover;
    opacity: 0.3;
    z-index: -1;
  }

  .hero h1 {
    font-size: 2.5rem;
    margin-bottom: 20px;
    text-shadow: 0 2px 4px rgba(0,0,0,0.3);
  }

  .hero p {
    font-size: 1.2rem;
    max-width: 800px;
    margin: 0 auto 30px;
  }

  article {
    background: rgba(255,255,255,0.05);
    backdrop-filter: blur(10px);
    border-radius: 15px;
    padding: 40px;
    margin-bottom: 50px;
    box-shadow: 0 10px 30px rgba(0,0,0,0.2);
  }

  article h2 {
    font-size: 2rem;
    margin-bottom: 30px;
    color: var(--accent-color);
    position: relative;
    padding-bottom: 15px;
  }

  article h2::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 100px;
    height: 3px;
    background: linear-gradient(90deg, var(--accent-color), transparent);
  }

  article h3 {
    font-size: 1.5rem;
    margin: 30px 0 20px;
    color: var(--accent-color);
  }

  article p {
    font-size: 1.1rem;
    margin-bottom: 20px;
    line-height: 1.8;
  }

  .image-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 20px;
    margin: 30px 0;
  }

  .image-card {
    background: var(--card-bg);
    border-radius: 10px;
    overflow: hidden;
    transition: var(--transition);
    box-shadow: 0 5px 15px rgba(0,0,0,0.1);
  }

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

  .image-card img {
    width: 100%;
    height: 200px;
    object-fit: cover;
    display: block;
  }

  .image-card .caption {
    padding: 15px;
    font-size: 0.9rem;
  }

  pre {
    background: rgba(0,0,0,0.3);
    border-radius: 8px;
    padding: 20px;
    margin: 20px 0;
    overflow-x: auto;
    font-family: 'Courier New', monospace;
    font-size: 0.9rem;
    line-height: 1.5;
    position: relative;
  }

  pre::before {
    content: 'CSS';
    position: absolute;
    top: 0;
    right: 0;
    background: var(--accent-color);
    color: white;
    padding: 2px 10px;
    font-size: 0.8rem;
    border-radius: 0 0 0 5px;
  }

  code {
    font-family: 'Courier New', monospace;
    background: rgba(0,0,0,0.2);
    padding: 2px 5px;
    border-radius: 3px;
    font-size: 0.9rem;
  }

  .card-container {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 30px;
    margin: 40px 0;
  }

  .card {
    background: var(--card-bg);
    border-radius: 15px;
    padding: 25px;
    transition: var(--transition);
    backdrop-filter: blur(5px);
    box-shadow: 0 5px 15px rgba(0,0,0,0.1);
  }

  .card:hover {
    transform: translateY(-10px);
    box-shadow: 0 15px 30px rgba(0,0,0,0.2);
    background: rgba(255,255,255,0.15);
  }

  .card h4 {
    font-size: 1.3rem;
    margin-bottom: 15px;
    color: var(--accent-color);
  }

  .footer {
    text-align: center;
    padding: 30px;
    background: rgba(0,0,0,0.2);
    margin-top: 50px;
    border-radius: 15px 15px 0 0;
  }

  @media (max-width: 992px) {
    .sidebar {
      width: 200px;
    }
  }

  @media (max-width: 768px) {
    .menu-toggle {
      display: block;
    }

    .sidebar {
      width: 80%;
    }

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

    article {
      padding: 30px;
    }

    .main-content {
      padding: 20px;
    }
  }

  @media (max-width: 576px) {
    .hero {
      padding: 40px 20px;
    }

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

    article {
      padding: 20px;
    }

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

  /* Animations */
  @keyframes float {
    0%, 100% { transform: translateY(0); }
    50% { transform: translateY(-20px); }
  }

  .floating {
    animation: float 6s ease-in-out infinite;
  }

  @keyframes pulse {
    0%, 100% { opacity: 1; }
    50% { opacity: 0.5; }
  }

  .pulse {
    animation: pulse 2s ease-in-out infinite;
  }