:root {
    --primary-color: #002B5B;
    --secondary-color: #6C757D;
    --background-color: #F8F9FA;
    --accent-orange: #FFA500;
    --accent-green: #28A745;
    --font-family: 'Roboto', sans-serif;
    --shadow-sm: 0 2px 8px rgba(0,0,0,0.1);
    --shadow-md: 0 4px 12px rgba(0,0,0,0.15);
    --transition: all 0.3s cubic-bezier(0.25, 0.8, 0.25, 1);
  }

  @font-face {
    font-family: 'Roboto';
    src: local('Roboto'), local('Roboto-Regular');
    font-weight: 400;
    font-style: normal;
  }

  body {
    background: linear-gradient(135deg, #f5f7fa 0%, #e4e8eb 100%);
    font-family: var(--font-family);
    color: var(--primary-color);
    line-height: 1.6;
    margin: 0;
    padding: 0;
    min-height: 100%;
  }

  .container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 2rem;
  }

  .header {
    background: linear-gradient(90deg, var(--primary-color) 0%, #003366 100%);
    color: white;
    padding: 2rem;
    border-radius: 0 0 20px 20px;
    box-shadow: var(--shadow-md);
    margin-bottom: 3rem;
    position: relative;
    overflow: hidden;
  }

  .header::before {
    content: "";
    position: absolute;
    top: -50%;
    left: -50%;
    width: 200%;
    height: 200%;
    background: radial-gradient(circle, rgba(255,255,255,0.1) 0%, transparent 70%);
    transform: rotate(30deg);
    z-index: 0;
  }

  .header-content {
    position: relative;
    z-index: 1;
  }

  h1, h2, h3, h4 {
    margin-top: 0;
    font-weight: 500;
  }

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

  h2 {
    font-size: 1.8rem;
    margin: 2rem 0 1rem;
    color: var(--primary-color);
    position: relative;
    padding-bottom: 0.5rem;
  }

  h2::after {
    content: "";
    position: absolute;
    bottom: 0;
    left: 0;
    width: 60px;
    height: 3px;
    background: linear-gradient(90deg, var(--accent-orange) 0%, var(--accent-green) 100%);
  }

  h3 {
    font-size: 1.4rem;
    margin: 1.5rem 0 0.8rem;
    color: var(--secondary-color);
  }

  p {
    font-size: 1.05rem;
    margin-bottom: 1.2rem;
    color: #444;
  }

  .note {
    background: rgba(0, 43, 91, 0.05);
    border-left: 4px solid var(--accent-orange);
    padding: 1rem;
    margin: 1.5rem 0;
    border-radius: 0 4px 4px 0;
  }

  .grid-container {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(500px, 1fr));
    gap: 2rem;
    margin: 2rem 0;
  }

  .card {
    background: white;
    border-radius: 12px;
    box-shadow: var(--shadow-sm);
    padding: 1.5rem;
    transition: var(--transition);
    position: relative;
    overflow: hidden;
  }

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

  .card::before {
    content: "";
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 4px;
    background: linear-gradient(90deg, var(--accent-orange) 0%, var(--accent-green) 100%);
  }

  .image-container {
    display: flex;
    flex-wrap: wrap;
    gap: 1rem;
    margin: 2rem 0;
    justify-content: center;
  }

  .decorative-image {
    width: 150px;
    height: 150px;
    border-radius: 12px;
    object-fit: cover;
    box-shadow: var(--shadow-sm);
    transition: var(--transition);
  }

  .decorative-image:hover {
    transform: scale(1.05);
    box-shadow: var(--shadow-md);
  }

  pre {
    background: #002B5B;
    color: #f8f9fa;
    padding: 1.5rem;
    border-radius: 8px;
    overflow-x: auto;
    margin: 1.5rem 0;
    box-shadow: var(--shadow-sm);
    position: relative;
  }

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

  code {
    font-family: 'Roboto Mono', monospace;
    font-size: 0.9rem;
    background: rgba(0, 43, 91, 0.1);
    padding: 0.2rem 0.4rem;
    border-radius: 4px;
    color: var(--primary-color);
  }

  table {
    width: 100%;
    border-collapse: collapse;
    margin: 2rem 0;
    box-shadow: var(--shadow-sm);
    border-radius: 8px;
    overflow: hidden;
  }

  th, td {
    padding: 1rem;
    text-align: left;
    border-bottom: 1px solid #dee2e6;
  }

  th {
    background-color: var(--primary-color);
    color: white;
    font-weight: 500;
  }

  tr:nth-child(even) {
    background-color: rgba(0, 43, 91, 0.03);
  }

  tr:hover {
    background-color: rgba(0, 43, 91, 0.05);
  }

  .reference {
    background: white;
    padding: 1.5rem;
    border-radius: 12px;
    box-shadow: var(--shadow-sm);
    margin: 3rem 0;
    text-align: center;
    font-style: italic;
    color: var(--secondary-color);
    border-top: 4px solid var(--accent-green);
  }

  .nav-tabs {
    display: flex;
    margin-bottom: 2rem;
    border-bottom: 1px solid #dee2e6;
  }

  .nav-tab {
    padding: 0.8rem 1.5rem;
    cursor: pointer;
    border-bottom: 3px solid transparent;
    transition: var(--transition);
    font-weight: 500;
    color: var(--secondary-color);
  }

  .nav-tab:hover {
    color: var(--primary-color);
    border-bottom-color: rgba(0, 43, 91, 0.3);
  }

  .nav-tab.active {
    color: var(--primary-color);
    border-bottom-color: var(--accent-orange);
  }

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

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

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