/* Modern NCERT Study Materials CSS Design */
        :root {
            --primary: #4361ee;
            --secondary: #3a0ca3;
            --accent: #7209b7;
            --light: #f8f9fa;
            --dark: #212529;
            --success: #4895ef;
            --warning: #f9c74f;
            --danger: #f94144;
            --gray: #6c757d;
            --light-bg: #f1faee;
            --card-shadow: 0 10px 20px rgba(0, 0, 0, 0.05);
            --hover-shadow: 0 15px 30px rgba(0, 0, 0, 0.1);
        }

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

        body {
            font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
            line-height: 1.6;
            color: var(--dark);
            background: linear-gradient(135deg, #f5f7fa 0%, #e4e7ec 100%);
            padding-top: 80px;
        }

        /* Navbar Styles */
        .navbar {
            box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
            background: rgba(255, 255, 255, 0.95) !important;
            backdrop-filter: blur(10px);
        }

        .navbar-brand {
            font-weight: 800;
            color: var(--primary) !important;
            font-size: 1.5rem;
        }

        .nav-link {
            font-weight: 500;
            transition: all 0.3s ease;
            position: relative;
            margin: 0 5px;
        }

        .nav-link:not(.active):hover {
            color: var(--primary) !important;
        }

        .nav-link.active {
            color: var(--primary) !important;
            font-weight: 600;
        }

        .nav-link.active::after {
            content: '';
            position: absolute;
            bottom: 0;
            left: 50%;
            transform: translateX(-50%);
            width: 30px;
            height: 3px;
            background: var(--primary);
            border-radius: 3px;
        }

        /* Materials Section */
        .materials {
            max-width: 1200px;
            margin: 0 auto;
            padding: 40px 20px 20px;
        }

        .materials h2 {
            text-align: center;
            font-size: 2.5rem;
            font-weight: 800;
            color: var(--primary);
            margin-bottom: 15px;
            position: relative;
            display: inline-block;
            width: 100%;
        }

        .materials h2::after {
            content: '';
            position: absolute;
            bottom: -10px;
            left: 50%;
            transform: translateX(-50%);
            width: 80px;
            height: 4px;
            background: var(--accent);
            border-radius: 2px;
        }

        .materials > p {
            text-align: center;
            font-size: 1.1rem;
            color: var(--gray);
            max-width: 800px;
            margin: 0 auto 40px;
            line-height: 1.8;
        }

        .material-list {
            background: white;
            border-radius: 16px;
            padding: 30px;
            margin-bottom: 40px;
            box-shadow: var(--card-shadow);
            transition: all 0.3s ease;
            position: relative;
            overflow: hidden;
        }

        .material-list::before {
            content: '';
            position: absolute;
            top: 0;
            left: 0;
            width: 5px;
            height: 100%;
            background: linear-gradient(to bottom, var(--primary), var(--secondary));
        }

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

        .material-list h3 {
            color: var(--primary);
            margin-bottom: 25px;
            padding-bottom: 15px;
            border-bottom: 1px solid #e9ecef;
            font-size: 1.6rem;
            display: flex;
            align-items: center;
            gap: 10px;
        }

        .subject-grid {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
            gap: 25px;
        }

        .subject {
            background: var(--light-bg);
            border-radius: 12px;
            padding: 20px;
            transition: all 0.3s ease;
            border-left: 4px solid var(--success);
        }

        .subject:nth-child(2n) {
            border-left-color: var(--warning);
        }

        .subject:nth-child(3n) {
            border-left-color: var(--accent);
        }

        .subject:hover {
            transform: translateY(-3px);
            box-shadow: var(--card-shadow);
        }

        .subject h4 {
            color: var(--dark);
            margin-bottom: 15px;
            font-size: 1.3rem;
            display: flex;
            align-items: center;
            gap: 8px;
        }

        .subject ul {
            list-style-type: none;
        }

        .subject li {
            margin-bottom: 10px;
            position: relative;
            padding-left: 5px;
        }

        .subject a {
            display: block;
            padding: 10px 15px;
            background: white;
            border-radius: 8px;
            color: var(--dark);
            text-decoration: none;
            transition: all 0.3s ease;
            box-shadow: 0 2px 5px rgba(0, 0, 0, 0.05);
            border-left: 3px solid var(--primary);
        }

        .subject a:hover {
            background: var(--primary);
            color: white;
            transform: translateX(5px);
        }

        /* Footer Styles */
        footer {
            margin-top: 60px;
            background: linear-gradient(to right, var(--dark), #2c3e50);
            padding: 40px 0 20px;
            color: white;
        }

        footer .container {
            display: flex;
            flex-direction: column;
            align-items: center;
        }

        footer .d-flex {
            margin-bottom: 20px;
        }

        footer a {
            color: rgba(255, 255, 255, 0.8) !important;
            text-decoration: none;
            transition: all 0.3s ease;
            padding: 0 15px;
            position: relative;
        }

        footer a:not(:last-child)::after {
            content: '•';
            position: absolute;
            right: -5px;
            color: rgba(255, 255, 255, 0.5);
        }

        footer a:hover {
            color: white !important;
        }

        footer p {
            color: rgba(255, 255, 255, 0.7);
            margin-top: 20px;
        }

        /* Animation for cards */
        @keyframes fadeIn {
            from {
                opacity: 0;
                transform: translateY(20px);
            }
            to {
                opacity: 1;
                transform: translateY(0);
            }
        }

        .material-list {
            animation: fadeIn 0.5s ease-out forwards;
        }

        .material-list:nth-child(2) {
            animation-delay: 0.1s;
        }

        .material-list:nth-child(3) {
            animation-delay: 0.2s;
        }

        .material-list:nth-child(4) {
            animation-delay: 0.3s;
        }

        /* Responsive Design */
        @media (max-width: 992px) {
            .subject-grid {
                grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
            }
        }

        @media (max-width: 768px) {
            .materials h2 {
                font-size: 2.2rem;
            }
            
            .materials > p {
                font-size: 1.1rem;
                padding: 0 15px;
            }
            
            .material-list {
                padding: 20px 15px;
                margin: 0 15px 30px;
            }
            
            .subject-grid {
                grid-template-columns: 1fr;
                gap: 20px;
            }
            
            footer a {
                padding: 0 10px;
                font-size: 0.9rem;
            }
        }

        @media (max-width: 576px) {
            body {
                padding-top: 70px;
            }
            
            .materials {
                padding: 30px 15px 10px;
            }
            
            .materials h2 {
                font-size: 1.8rem;
            }
            
            .material-list h3 {
                font-size: 1.5rem;
            }
            
            .subject {
                padding: 15px;
            }
            
            footer .d-flex {
                flex-wrap: wrap;
                justify-content: center;
                gap: 10px;
            }
            
            footer a:not(:last-child)::after {
                display: none;
            }
        }

        /* Print Styles */
        @media print {
            .navbar, footer {
                display: none !important;
            }
            
            body {
                padding-top: 0;
                background: white;
            }
            
            .material-list {
                box-shadow: none;
                border: 1px solid #ddd;
                page-break-inside: avoid;
            }
            
            .subject a {
                color: var(--dark);
                text-decoration: underline;
            }
        }