* {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
            font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
        }
        
        :root {
            --primary: #3498db;
            --secondary: #2c3e50;
            --accent: #e74c3c;
            --light: #f9f9f9;
            --dark: #2c3e50;
            --success: #2ecc71;
            --warning: #f39c12;
            --physics: #8e44ad;
        }
        
        body {
            background-color: #f5f7fa;
            color: #333;
            line-height: 1.6;
        }
        
        header {
            background: linear-gradient(to right, var(--secondary), var(--physics));
            color: white;
            padding: 1.5rem 0;
            box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
        }
        
        .container {
            align-items: center;
            width: 100%;
            margin:auto;
            max-width: 1200px;
            margin-top:  1rem;
            padding: 0 15px;
        }
        
        .header-content {
            display: flex;
            justify-content: space-between;
            align-items: center;
            flex-wrap: wrap;
        }
        
        .logo {
            display: flex;
            align-items: center;
            gap: 15px;
        }
        
        .logo i {
            font-size: 2.5rem;
            color: var(--warning);
        }
        
        .logo h1 {
            font-size: 1.8rem;
        }
        
        nav ul {
            display: flex;
            list-style: none;
            flex-wrap: wrap;
        }
        
        nav ul li {
            margin-left: 25px;
        }
        
        nav ul li a {
            color: white;
            text-decoration: none;
            font-weight: 600;
            padding: 8px 12px;
            border-radius: 4px;
            transition: all 0.3s ease;
        }
        
        nav ul li a:hover {
            background-color: rgba(255, 255, 255, 0.2);
        }
        
        .subject-header {
            height: fit-content;
            padding-top: 10px;    /* Adjust this for more/less height */
            padding-bottom: 10px; /* Adjust this for more/less height */
            background: linear-gradient(to right, #8e44ad, #3498db);
            color: white;
            padding: .10rem 0;
            margin-bottom: 1rem;
            border-radius: 0 0 10px 10px;
            min-height: 100px; /* The section will never be shorter than 300px */
            display: flex;
            align-items: center; /* Vertically centers the content inside */
        }
        
        .subject-header h1 {
            font-size: 2.2rem;
            margin-top: 0.5rem;
            margin-bottom: 0.5rem;
        }
        
        .subject-info {
            display: flex;
            justify-content: space-between;
            align-items: center;
            flex-wrap: wrap;
            margin-bottom: 1.5rem;
        }
        
        .back-link {
            display: inline-flex;
            align-items: center;
            color: white;
            text-decoration: none;
            font-weight: 600;
            margin-bottom: 1.5rem;
            background-color: rgba(0,0,0,0.2);
            padding: 8px 16px;
            border-radius: 4px;
        }
        
        .back-link i {
            margin-right: 8px;
        }
        
        .back-link:hover {
            background-color: rgba(0,0,0,0.3);
        }
        
        .seo-content {
            width: 100%;
            background-color: white;
            padding: 1rem;
            border-radius: 10px;
            margin-bottom: 2rem;
            box-shadow: 0 4px 6px rgba(0, 0, 0, 0.05);
        }
        
        .seo-content h3 {
            color: var(--secondary);
            margin-bottom: 1rem;
            font-size: 1.5rem;
        }
        
        .seo-content p {
            margin-bottom: 1rem;
            color: #555;
        }
        
        .chapters-grid {
            display: grid;
            grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
            gap: 25px;
            margin-bottom: 3rem;
        }
        
        .chapter-card {
            background-color: white;
            border-radius: 10px;
            overflow: hidden;
            box-shadow: 0 6px 15px rgba(0, 0, 0, 0.08);
            transition: transform 0.3s ease, box-shadow 0.3s ease;
        }
        
        .chapter-card:hover {
            transform: translateY(-5px);
            box-shadow: 0 12px 20px rgba(0, 0, 0, 0.1);
        }
        
        .chapter-header {
            background: linear-gradient(to right, var(--physics), #3498db);
            color: white;
            padding: .50rem;
            align-items: center;
            text-align: center;
        }
        
        .chapter-header h3 {
            font-size: 1.4rem;
            margin-bottom: 0.5rem;
            text-align: center;
        }
        
        .chapter-number {
            display: inline-block;
            background-color: rgba(255, 255, 255, 0.2);
            padding: 3px 10px;
            border-radius: 20px;
            font-size: 0.9rem;
            margin-bottom: 0.5rem;
        }
        
        .chapter-body {
            padding: 1.5rem;
            min-height: 180px;
        }
        
        .chapter-topics {
            list-style-type: none;
            margin-top: 1rem;
        }
        
        .chapter-topics li {
            padding: 6px 0;
            border-bottom: 1px dashed #eee;
            display: flex;
            align-items: center;
            font-size: 0.9rem;
            color: #666;
        }
        
        .chapter-topics li i {
            color: var(--physics);
            margin-right: 10px;
            font-size: 0.8rem;
        }
        
        .btn {
            display: inline-block;
            background-color: var(--physics);
            color: white;
            padding: 10px 20px;
            border-radius: 5px;
            text-decoration: none;
            font-weight: 600;
            transition: background-color 0.3s ease;
            border: none;
            cursor: pointer;
            text-align: center;
        }
        
        .btn:hover {
            background-color: #7d3c98;
        }
        
        .btn-block {
            display: block;
            width: 100%;
            margin-top: 1rem;
        }
        
        .test-types {
            display: grid;
            grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
            gap: 20px;
            margin-top: 2rem;
        }
        
        .test-type {
            background-color: #f8f9fa;
            padding: 1.5rem;
            border-radius: 8px;
            border-left: 4px solid var(--physics);
        }
        
        .test-type h4 {
            color: var(--secondary);
            margin-bottom: 0.5rem;
            display: flex;
            align-items: center;
        }
        
        .test-type h4 i {
            margin-right: 10px;
            color: var(--physics);
        }
        
        .test-type p {
            color: #666;
            font-size: 0.9rem;
        }
        
        footer {
            background-color: var(--secondary);
            color: white;
            padding: 2rem 0;
            text-align: center;
            margin-top: 3rem;
        }
        
        .footer-content {
            display: flex;
            flex-direction: column;
            align-items: center;
        }
        
        .footer-links {
            display: flex;
            margin: 1.5rem 0;
            flex-wrap: wrap;
            justify-content: center;
            gap: 20px;
        }
        
        .footer-links a {
            color: #ddd;
            text-decoration: none;
            transition: color 0.3s ease;
        }
        
        .footer-links a:hover {
            color: white;
        }
        
        .copyright {
            color: #aaa;
            font-size: 0.9rem;
            margin-top: 1rem;
        }
        
        .subject-stats {
            display: flex;
            gap: 20px;
            margin-top: 1rem;
            flex-wrap: wrap;
        }
        
        .stat {
            background-color: rgba(255, 255, 255, 0.1);
            padding: 8px 15px;
            border-radius: 20px;
            font-size: 0.9rem;
        }
        
        @media (max-width: 768px) {
            .header-content {
                flex-direction: column;
                text-align: center;
            }
            
            nav ul {
                margin-top: 1rem;
                justify-content: center;
            }
            
            nav ul li {
                margin: 0 10px;
            }
            
            .subject-header h1 {
                font-size: 1.8rem;
            }
            
            .chapters-grid {
                grid-template-columns: 1fr;
            }
            
            .test-types {
                grid-template-columns: 1fr;
            }
        }
        
        @media (max-width: 480px) {
            .chapters-grid {
                grid-template-columns: 1fr;
            }
            
            .subject-info {
                flex-direction: column;
                align-items: flex-start;
            }
        }