body {
            font-family: 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
            line-height: 1.6;
            color: #2c3e50;
            background-color: #f8fafc;
            margin: 0;
            padding: 0;
        }
        .container {
            max-width: 1000px;
            margin: 0 auto;
            padding: 20px;
        }
        .site-header {
            background: linear-gradient(135deg, #1e3c72 0%, #2a5298 100%);
            color: white;
            padding: 1rem 0;
            border-bottom: 3px solid #f39c12;
        }
        .site-header .container {
            display: flex;
            justify-content: space-between;
            align-items: center;
        }
        .site-header a {
            color: white;
            text-decoration: none;
        }
        .site-header h1 {
            margin: 0;
            font-size: 1.5rem;
            font-weight: 400;
        }
        .site-header .nav-links a {
            margin-left: 20px;
            font-size: 0.9rem;
            color: #e0e0e0;
        }
        .site-header .nav-links a:hover {
            color: #f39c12;
        }
        article {
            background-color: white;
            border-radius: 12px;
            box-shadow: 0 5px 15px rgba(0,0,0,0.1);
            padding: 2rem;
            margin: 2rem 0;
        }
        h2 {
            color: #1e3c72;
            border-bottom: 2px solid #f39c12;
            padding-bottom: 0.3rem;
            margin-top: 0;
        }
        h3 {
            color: #2a5298;
            margin-top: 1.8rem;
        }
        .learning-objectives {
            background-color: #e8f0fe;
            border-left: 5px solid #2a5298;
            padding: 1rem 1.5rem;
            margin: 1.5rem 0;
            border-radius: 0 8px 8px 0;
        }
        .learning-objectives ul {
            margin-bottom: 0;
        }
        .figure {
            background-color: #f0f0f0;
            border: 1px dashed #aaa;
            text-align: center;
            padding: 20px;
            margin: 20px 0;
            font-family: monospace;
            border-radius: 5px;
        }
        pre {
            background-color: #2d2d2d;
            color: #f8f8f2;
            padding: 1rem;
            border-radius: 8px;
            overflow-x: auto;
            font-size: 0.9rem;
            border-left: 3px solid #f39c12;
        }
        code {
            font-family: 'Courier New', Courier, monospace;
        }
        p code, li code {
            background-color: #ecf0f1;
            padding: 2px 5px;
            border-radius: 3px;
            color: #c7254e;
        }
        .worked-out {
            background-color: #fef9e7;
            border-left: 5px solid #f39c12;
            padding: 1rem 1.5rem;
            margin: 1.5rem 0;
            border-radius: 0 8px 8px 0;
        }
        .worked-out h4 {
            color: #d35400;
            margin-top: 0;
        }
        .table {
            width: 100%;
            border-collapse: collapse;
            margin: 1rem 0;
        }
        .table th, .table td {
            border: 1px solid #ddd;
            padding: 8px;
            text-align: left;
        }
        .table th {
            background-color: #2a5298;
            color: white;
        }
        .exercise-tabs {
            display: flex;
            flex-wrap: wrap;
            margin: 2rem 0 0 0;
            border-bottom: 2px solid #f39c12;
        }
        .tab-button {
            background-color: #ecf0f1;
            border: none;
            padding: 12px 20px;
            cursor: pointer;
            font-weight: bold;
            color: #2c3e50;
            border-radius: 8px 8px 0 0;
            margin-right: 5px;
        }
        .tab-button.active {
            background-color: #f39c12;
            color: white;
        }
        .tab-content {
            background-color: white;
            border: 1px solid #ddd;
            border-top: none;
            padding: 1.5rem;
            border-radius: 0 0 8px 8px;
        }
        .tab-pane {
            display: none;
        }
        .tab-pane.active {
            display: block;
        }
        .bottom-nav {
            display: flex;
            justify-content: space-between;
            margin: 2rem 0;
        }
        .bottom-nav a {
            background-color: #2a5298;
            color: white;
            padding: 10px 15px;
            text-decoration: none;
            border-radius: 5px;
            font-size: 0.9rem;
            transition: background-color 0.3s ease;
        }
        .bottom-nav a:hover {
            background-color: #1e3c72;
        }
        .bottom-nav .prev {
            background-color: #95a5a6;
        }
        .bottom-nav .prev:hover {
            background-color: #7f8c8d;
        }
        footer {
            text-align: center;
            margin-top: 2rem;
            padding: 1rem 0;
            border-top: 1px solid #ddd;
            color: #7f8c8d;
        }