:root {
            --primary: #2A6AC8;
            --secondary: #4CAF50;
            --accent: #FF9800;
            --light: #F5F9FF;
            --dark: #333;
            --gray: #777;
            --light-gray: #e0e0e0;
        }
        
        * {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
        }
        
        body {
            font-family: 'Poppins', sans-serif;
            line-height: 1.6;
            color: var(--dark);
            background-color: #f8f9fa;
        }
        
        .container {
            width: 100%;
            max-width: 1200px;
            margin: 0 auto;
            padding: 0 20px;
        }
        
        /* Header Styles */
        header {
            background: linear-gradient(135deg, var(--primary), #1a4d9e);
            color: white;
            padding: 15px 0;
            position: sticky;
            top: 0;
            z-index: 100;
            box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
        }
        
        .header-content {
            display: flex;
            justify-content: space-between;
            align-items: center;
        }
        
        .logo {
            display: flex;
            align-items: center;
            gap: 10px;
        }
        
        .logo i {
            font-size: 28px;
        }
        
        .logo h1 {
            font-size: 24px;
            font-weight: 600;
        }
        
        nav ul {
            display: flex;
            list-style: none;
            gap: 25px;
        }
        
        nav a {
            color: white;
            text-decoration: none;
            font-weight: 500;
            transition: opacity 0.3s;
        }
        
        nav a:hover {
            opacity: 0.8;
        }
        
        .auth-buttons {
            display: flex;
            gap: 15px;
        }
        
        .btn {
            padding: 8px 20px;
            border-radius: 50px;
            border: none;
            font-weight: 500;
            cursor: pointer;
            transition: all 0.3s;
        }
        
        .btn-outline {
            background: transparent;
            border: 2px solid white;
            color: white;
        }
        
        .btn-primary {
            background: var(--secondary);
            color: white;
        }
        
        .btn-accent {
            background: var(--accent);
            color: white;
        }
        
        /* Hero Section */
        .hero {
            padding: 80px 0;
            background: linear-gradient(rgba(42, 106, 200, 0.9), rgba(26, 77, 158, 0.9)), url('https://images.unsplash.com/photo-1576091160399-112ba8d25d1f?ixlib=rb-4.0.3&auto=format&fit=crop&w=1500&q=80');
            background-size: cover;
            background-position: center;
            color: white;
            text-align: center;
        }
        
        .hero h2 {
            font-size: 2.8rem;
            margin-bottom: 20px;
        }
        
        .hero p {
            font-size: 1.2rem;
            max-width: 700px;
            margin: 0 auto 30px;
        }
        
        .hero-buttons {
            display: flex;
            gap: 15px;
            justify-content: center;
        }
        
        .btn-large {
            padding: 12px 30px;
            font-size: 1.1rem;
        }
        
        /* Features Section */
        .features {
            padding: 80px 0;
            background: var(--light);
        }
        
        .section-title {
            text-align: center;
            margin-bottom: 50px;
        }
        
        .section-title h2 {
            font-size: 2.2rem;
            color: var(--primary);
            margin-bottom: 15px;
        }
        
        .section-title p {
            color: var(--gray);
            max-width: 700px;
            margin: 0 auto;
        }
        
        .features-grid {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
            gap: 30px;
        }
        
        .feature-card {
            background: white;
            border-radius: 10px;
            padding: 30px;
            box-shadow: 0 5px 15px rgba(0, 0, 0, 0.05);
            transition: transform 0.3s;
        }
        
        .feature-card:hover {
            transform: translateY(-5px);
        }
        
        .feature-icon {
            background: var(--primary);
            color: white;
            width: 60px;
            height: 60px;
            border-radius: 50%;
            display: flex;
            align-items: center;
            justify-content: center;
            font-size: 24px;
            margin-bottom: 20px;
        }
        
        .feature-card h3 {
            font-size: 1.4rem;
            margin-bottom: 15px;
            color: var(--dark);
        }
        
        /* Flashcard Generator */
        .flashcard-generator {
            padding: 80px 0;
            background: white;
        }
        
        .generator-container {
            display: grid;
            grid-template-columns: 1fr 1fr;
            gap: 40px;
            align-items: start;
        }
        
        .input-section {
            background: var(--light);
            padding: 25px;
            border-radius: 10px;
        }
        
        .input-section h3 {
            margin-bottom: 20px;
            color: var(--primary);
        }
        
        textarea {
            width: 100%;
            height: 200px;
            padding: 15px;
            border: 1px solid var(--light-gray);
            border-radius: 8px;
            font-family: inherit;
            margin-bottom: 15px;
            resize: vertical;
        }
        
        .output-section {
            display: flex;
            flex-direction: column;
            gap: 20px;
        }
        
        .flashcard {
            perspective: 1000px;
            height: 200px;
        }
        
        .flashcard-inner {
            position: relative;
            width: 100%;
            height: 100%;
            transition: transform 0.6s;
            transform-style: preserve-3d;
            cursor: pointer;
        }
        
        .flashcard.flipped .flashcard-inner {
            transform: rotateY(180deg);
        }
        
        .flashcard-front, .flashcard-back {
            position: absolute;
            width: 100%;
            height: 100%;
            backface-visibility: hidden;
            border-radius: 10px;
            padding: 20px;
            display: flex;
            align-items: center;
            justify-content: center;
            box-shadow: 0 4px 10px rgba(0, 0, 0, 0.1);
        }
        
        .flashcard-front {
            background: var(--primary);
            color: white;
            font-size: 1.2rem;
            font-weight: 500;
            text-align: center;
        }
        
        .flashcard-back {
            background: var(--secondary);
            color: white;
            transform: rotateY(180deg);
            text-align: center;
        }
        
        /* Courses Section */
        .courses {
            padding: 80px 0;
            background: var(--light);
        }
        
        .courses-grid {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
            gap: 30px;
        }
        
        .course-card {
            background: white;
            border-radius: 10px;
            overflow: hidden;
            box-shadow: 0 5px 15px rgba(0, 0, 0, 0.05);
        }
        
        .course-image {
            height: 180px;
            background-size: cover;
            background-position: center;
        }
        
        .course-content {
            padding: 20px;
        }
        
        .course-content h3 {
            margin-bottom: 10px;
            color: var(--dark);
        }
        
        .course-content p {
            color: var(--gray);
            margin-bottom: 20px;
        }
        
        /* Textbook Library */
        .textbook-library {
            padding: 80px 0;
            background: white;
        }
        
        .textbooks-grid {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
            gap: 25px;
        }
        
        .textbook-card {
            background: var(--light);
            border-radius: 10px;
            padding: 20px;
            text-align: center;
            box-shadow: 0 4px 10px rgba(0, 0, 0, 0.05);
            transition: transform 0.3s;
        }
        
        .textbook-card:hover {
            transform: translateY(-5px);
        }
        
        .textbook-icon {
            font-size: 40px;
            color: var(--primary);
            margin-bottom: 15px;
        }
        
        .textbook-card h3 {
            margin-bottom: 10px;
            color: var(--dark);
        }
        
        .textbook-card p {
            color: var(--gray);
            margin-bottom: 15px;
            font-size: 0.9rem;
        }
        
        /* Video Resources */
        .video-resources {
            padding: 80px 0;
            background: var(--light);
        }
        
        .videos-container {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
            gap: 30px;
        }
        
        .video-card {
            background: white;
            border-radius: 10px;
            overflow: hidden;
            box-shadow: 0 5px 15px rgba(0, 0, 0, 0.05);
        }
        
        .video-placeholder {
            height: 180px;
            background: var(--dark);
            display: flex;
            align-items: center;
            justify-content: center;
            color: white;
            font-size: 3rem;
        }
        
        .video-content {
            padding: 20px;
        }
        
        .video-content h3 {
            margin-bottom: 10px;
            color: var(--dark);
        }
        
        .video-content p {
            color: var(--gray);
            margin-bottom: 15px;
        }
        
        /* AI Assistant Demo */
        .ai-assistant {
            padding: 80px 0;
            background: white;
        }
        
        .ai-demo {
            background: var(--light);
            padding: 30px;
            border-radius: 10px;
            margin-top: 30px;
        }
        
        .sample-text {
            padding: 20px;
            background: white;
            border-radius: 8px;
            margin-bottom: 20px;
            line-height: 1.8;
        }
        
        .highlightable {
            padding: 2px 4px;
            border-radius: 3px;
            transition: background 0.3s;
        }
        
        .highlightable:hover {
            background: rgba(255, 152, 0, 0.2);
            cursor: pointer;
        }
        
        .ai-response {
            padding: 20px;
            background: white;
            border-radius: 8px;
            margin-top: 20px;
            display: none;
        }
        
        .ai-response.show {
            display: block;
        }
        
        /* Footer */
        footer {
            background: var(--dark);
            color: white;
            padding: 60px 0 30px;
        }
        
        .footer-content {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
            gap: 40px;
            margin-bottom: 40px;
        }
        
        .footer-column h3 {
            font-size: 1.2rem;
            margin-bottom: 20px;
            color: var(--accent);
        }
        
        .footer-column ul {
            list-style: none;
        }
        
        .footer-column ul li {
            margin-bottom: 10px;
        }
        
        .footer-column a {
            color: #ccc;
            text-decoration: none;
            transition: color 0.3s;
        }
        
        .footer-column a:hover {
            color: white;
        }
        
        .copyright {
            text-align: center;
            padding-top: 20px;
            border-top: 1px solid #444;
            color: #ccc;
        }
        
        /* Responsive Design */
        @media (max-width: 768px) {
            .generator-container {
                grid-template-columns: 1fr;
            }
            
            .header-content {
                flex-direction: column;
                gap: 15px;
            }
            
            nav ul {
                gap: 15px;
                flex-wrap: wrap;
                justify-content: center;
            }
            
            .hero h2 {
                font-size: 2.2rem;
            }
        }