:root {
    --main-color: #1E3A8A;
    --accent-color: #FFD700;
    --secondary-color: #A0E6C3;
    --highlight-color: #FF6B6B;
    --text-color: #333333;
    --light-text: #FFFFFF;
    --bg-gradient: linear-gradient(135deg, #1E3A8A, #0F1A3D);
    --card-bg: rgba(255, 255, 255, 0.95);
    --section-padding: 80px 0;
  }

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

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

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

  .header {
    text-align: center;
    padding: 40px 0;
    position: relative;
  }

  .header::after {
    content: "";
    position: absolute;
    bottom: 0;
    left: 50%;
    transform: translateX(-50%);
    width: 200px;
    height: 3px;
    background: var(--accent-color);
    border-radius: 3px;
  }

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

  .subtitle {
    font-size: 1.2rem;
    color: var(--secondary-color);
    margin-bottom: 30px;
  }

  .notice {
    background-color: rgba(255, 255, 255, 0.1);
    border-left: 4px solid var(--accent-color);
    padding: 15px;
    margin: 30px 0;
    color: var(--light-text);
    font-size: 0.9rem;
  }

  article {
    background-color: var(--card-bg);
    border-radius: 15px;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.2);
    padding: 40px;
    margin: 40px 0;
  }

  h2 {
    color: var(--main-color);
    font-size: 1.8rem;
    margin: 30px 0 20px;
    position: relative;
    padding-bottom: 10px;
  }

  h2::after {
    content: "";
    position: absolute;
    bottom: 0;
    left: 0;
    width: 60px;
    height: 3px;
    background: var(--accent-color);
  }

  h3 {
    color: var(--main-color);
    font-size: 1.4rem;
    margin: 25px 0 15px;
  }

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

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

  .image-card {
    border-radius: 10px;
    overflow: hidden;
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.1);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
  }

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

  .image-card img {
    width: 100%;
    height: auto;
    display: block;
    border-radius: 10px;
  }

  pre {
    background-color: #2D3748;
    color: #E2E8F0;
    padding: 20px;
    border-radius: 8px;
    overflow-x: auto;
    margin: 25px 0;
    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: var(--main-color);
    padding: 2px 10px;
    border-radius: 0 0 0 8px;
    font-size: 0.8rem;
    font-weight: bold;
  }

  code {
    background-color: rgba(255, 215, 0, 0.1);
    color: var(--main-color);
    padding: 2px 5px;
    border-radius: 3px;
    font-family: 'Courier New', monospace;
    font-size: 0.9rem;
  }

  .nav-tabs {
    display: flex;
    justify-content: center;
    margin: 40px 0;
    position: sticky;
    top: 0;
    background: rgba(30, 58, 138, 0.9);
    padding: 15px 0;
    z-index: 100;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
  }

  .nav-tabs a {
    color: var(--accent-color);
    text-decoration: none;
    margin: 0 15px;
    font-weight: 500;
    padding: 5px 10px;
    border-radius: 5px;
    transition: all 0.3s ease;
  }

  .nav-tabs a:hover {
    background: rgba(255, 215, 0, 0.2);
    color: var(--light-text);
  }

  .footer {
    text-align: center;
    padding: 30px 0;
    color: var(--light-text);
    font-size: 0.9rem;
    margin-top: 50px;
  }

  @media (max-width: 768px) {
    .image-grid {
      grid-template-columns: 1fr;
    }
    
    h1 {
      font-size: 2rem;
    }
    
    h2 {
      font-size: 1.5rem;
    }
    
    article {
      padding: 25px;
    }
  }

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

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

  /* Decorative elements */
  .decorative-circle {
    position: absolute;
    width: 200px;
    height: 200px;
    border-radius: 50%;
    background: radial-gradient(circle, rgba(255, 215, 0, 0.1), transparent 70%);
    z-index: -1;
  }

  .circle-1 {
    top: 10%;
    left: 5%;
  }

  .circle-2 {
    bottom: 15%;
    right: 5%;
  }

  /* Card styles */
  .feature-card {
    background: var(--card-bg);
    border-radius: 15px;
    padding: 30px;
    margin: 20px 0;
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.1);
    transition: all 0.3s ease;
  }

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

  .feature-card h4 {
    color: var(--main-color);
    margin-bottom: 15px;
    font-size: 1.2rem;
  }

  /* Responsive adjustments */
  @media (max-width: 480px) {
    .nav-tabs {
      flex-wrap: wrap;
    }
    
    .nav-tabs a {
      margin: 5px;
    }
    
    h1 {
      font-size: 1.8rem;
    }
    
    article {
      padding: 20px;
    }
  }