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

        :root {
            --primary: #0aff9d;
            --dark: #0f0f0f;
            --gray: #1a1a1a;
            --light-gray: #2a2a2a;
            --white: #ffffff;
            --text-gray: #a0a0a0;
        }

        body {
            font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
            background: var(--dark);
            color: var(--white);
            line-height: 1.6;
            overflow-x: hidden;
        }

        /* Navigation */
        nav {
            position: fixed;
            top: 0;
            width: 100%;
            background: rgba(15, 15, 15, 0.95);
            backdrop-filter: blur(10px);
            padding: 1.2rem 5%;
            z-index: 1000;
            border-bottom: 1px solid var(--light-gray);
        }

        .nav-container {
            max-width: 1400px;
            margin: 0 auto;
            display: flex;
            justify-content: space-between;
            align-items: center;
        }

        .logo {
            font-size: 1.8rem;
            font-weight: 800;
            background: linear-gradient(135deg, var(--primary), #00d4ff);
            -webkit-background-clip: text;
            -webkit-text-fill-color: transparent;
            background-clip: text;
        }

        .nav-links {
            display: flex;
            gap: 2.5rem;
            list-style: none;
        }

        .nav-links a {
            color: var(--white);
            text-decoration: none;
            font-weight: 500;
            transition: color 0.3s;
            cursor: pointer;
        }

        .nav-links a:hover {
            color: var(--primary);
        }

        .mobile-toggle {
            display: none;
            flex-direction: column;
            gap: 5px;
            cursor: pointer;
        }

        .mobile-toggle span {
            width: 25px;
            height: 3px;
            background: var(--white);
            transition: 0.3s;
        }

        /* Hero Section */
        .hero {
            min-height: 100vh;
            display: flex;
            align-items: center;
            justify-content: center;
            text-align: center;
            padding: 8rem 5% 4rem;
            background: linear-gradient(135deg, #0f0f0f 0%, #1a1a1a 100%);
            position: relative;
            overflow: hidden;
        }

        .hero::before {
            content: '';
            position: absolute;
            width: 500px;
            height: 500px;
            background: radial-gradient(circle, rgba(10, 255, 157, 0.1), transparent);
            top: -250px;
            right: -250px;
            border-radius: 50%;
        }

        .hero-content {
            max-width: 900px;
            position: relative;
            z-index: 1;
        }

        .hero h1 {
            font-size: 4.5rem;
            font-weight: 900;
            margin-bottom: 1.5rem;
            line-height: 1.1;
            background: linear-gradient(135deg, var(--white), var(--primary));
            -webkit-background-clip: text;
            -webkit-text-fill-color: transparent;
            background-clip: text;
        }

        .hero p {
            font-size: 1.4rem;
            color: var(--text-gray);
            margin-bottom: 3rem;
            max-width: 600px;
            margin-left: auto;
            margin-right: auto;
        }

        .cta-btn {
            display: inline-block;
            padding: 1.2rem 3rem;
            background: linear-gradient(135deg, var(--primary), #00d4ff);
            color: var(--dark);
            text-decoration: none;
            font-weight: 700;
            font-size: 1.1rem;
            border-radius: 50px;
            border: none;
            cursor: pointer;
            transition: transform 0.3s, box-shadow 0.3s;
        }

        .cta-btn:hover {
            transform: translateY(-3px);
            box-shadow: 0 10px 30px rgba(10, 255, 157, 0.4);
        }

        /* Section Styles */
        section {
            padding: 5rem 5%;
            max-width: 1400px;
            margin: 0 auto;
        }

        .section-header {
            text-align: center;
            margin-bottom: 4rem;
        }

        .section-header h2 {
            font-size: 3rem;
            font-weight: 800;
            margin-bottom: 1rem;
        }

        .section-header p {
            font-size: 1.2rem;
            color: var(--text-gray);
        }

        /* Course Grid */
        .course-grid {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
            gap: 2.5rem;
        }

        .course-card {
            background: var(--gray);
            border-radius: 16px;
            overflow: hidden;
            transition: transform 0.3s, box-shadow 0.3s;
            cursor: pointer;
            border: 1px solid var(--light-gray);
        }

        .course-card:hover {
            transform: translateY(-10px);
            box-shadow: 0 20px 40px rgba(0, 0, 0, 0.5);
        }

        .course-image {
            width: 100%;
            height: 200px;
            background: linear-gradient(135deg, var(--light-gray), var(--gray));
            display: flex;
            align-items: center;
            justify-content: center;
            font-size: 3rem;
            position: relative;
            overflow: hidden;
        }

        .course-image::after {
            content: '';
            position: absolute;
            inset: 0;
            background: linear-gradient(135deg, transparent, rgba(10, 255, 157, 0.1));
        }

        .course-content {
            padding: 10px;
        }

        .chapter-description {
            padding-top: 1rem;
            padding-bottom: 1rem;
            color: var(--primary);
        }

        .course-tag {
            display: inline-block;
            padding: 0.4rem 1rem;
            background: var(--primary);
            color: var(--dark);
            font-size: 0.85rem;
            font-weight: 700;
            border-radius: 20px;
            margin-bottom: 1rem;
        }

        .course-card h3 {
            font-size: 1.5rem;
            margin-bottom: 0.8rem;
            font-weight: 700;
        }

        .course-card p {
            color: var(--text-gray);
            margin-bottom: 1.5rem;
            font-size: 0.95rem;
        }

        .enroll-btn {
            width: 100%;
            padding: 0.9rem;
            background: var(--light-gray);
            color: var(--white);
            border: 2px solid var(--light-gray);
            border-radius: 8px;
            font-weight: 600;
            cursor: pointer;
            transition: all 0.3s;
            font-size: 1rem;
        }

        .enroll-btn:hover {
            background: transparent;
            border-color: var(--primary);
            color: var(--primary);
        }

        /* Testimonials */
        .testimonials {
            background: var(--gray);
            border-radius: 20px;
            padding: 2rem 1rem;
            margin: 3rem 0;
        }

        .testimonial-grid {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
            gap: 2.5rem;
            margin-top: 3rem;
        }

        .testimonial-card {
            background: var(--light-gray);
            padding: 2rem;
            border-radius: 12px;
            border-left: 4px solid var(--primary);
        }

        .testimonial-card p {
            font-style: italic;
            color: var(--text-gray);
            margin-bottom: 1.5rem;
        }

        .testimonial-author {
            font-weight: 700;
            color: var(--white);
        }

        /* Search Bar */
        .search-container {
            max-width: 600px;
            margin: 0 auto 3rem;
        }

        .search-bar {
            width: 100%;
            padding: 1.2rem 1.5rem;
            background: var(--gray);
            border: 2px solid var(--light-gray);
            border-radius: 50px;
            color: var(--white);
            font-size: 1rem;
            transition: border-color 0.3s;
        }

        .search-bar:focus {
            outline: none;
            border-color: var(--primary);
        }

        /* Upload Form */
        .upload-form {
            max-width: 700px;
            margin: 0 auto;
            background: var(--gray);
            padding: 3rem;
            border-radius: 16px;
            border: 1px solid var(--light-gray);
        }

        .form-group {
            margin-bottom: 2rem;
        }

        .form-group label {
            display: block;
            margin-bottom: 0.8rem;
            font-weight: 600;
            color: var(--white);
        }

        .form-group input,
        .form-group textarea {
            width: 100%;
            padding: 1rem;
            background: var(--light-gray);
            border: 2px solid var(--light-gray);
            border-radius: 8px;
            color: var(--white);
            font-size: 1rem;
            font-family: inherit;
            transition: border-color 0.3s;
        }

        .form-group textarea {
            min-height: 120px;
            resize: vertical;
        }

        .form-group input:focus,
        .form-group textarea:focus {
            outline: none;
            border-color: var(--primary);
        }

        /* Modal (retained for compatibility, though modals removed) */
        .modal {
            display: none;
            position: fixed;
            top: 0;
            left: 0;
            width: 100%;
            height: 100%;
            background: rgba(0, 0, 0, 0.9);
            z-index: 2000;
            align-items: center;
            justify-content: center;
            padding: 2rem;
        }

        .modal.active {
            display: flex;
        }

        .modal-content {
            background: var(--gray);
            padding: 3rem;
            border-radius: 20px;
            max-width: 800px;
            width: 100%;
            max-height: 90vh;
            overflow-y: auto;
            position: relative;
            border: 1px solid var(--light-gray);
        }

        .close-modal {
            position: absolute;
            top: 1.5rem;
            right: 1.5rem;
            font-size: 2rem;
            color: var(--text-gray);
            cursor: pointer;
            background: none;
            border: none;
            transition: color 0.3s;
        }

        .close-modal:hover {
            color: var(--white);
        }

        .video-container {
            position: relative;
            padding-bottom: 56.25%;
            height: 0;
            margin: 2rem 0;
            border-radius: 12px;
            overflow: hidden;
        }

        .video-container iframe {
            position: absolute;
            top: 0;
            left: 0;
            width: 100%;
            height: 100%;
        }

        /* Footer */
        footer {
            background: var(--gray);
            padding: 4rem 5% 2rem;
            border-top: 1px solid var(--light-gray);
        }

        .footer-content {
            max-width: 1400px;
            margin: 0 auto;
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
            gap: 3rem;
            margin-bottom: 3rem;
        }

        .footer-section h3 {
            margin-bottom: 1.5rem;
            font-size: 1.3rem;
        }

        .footer-links {
            list-style: none;
        }

        .footer-links li {
            margin-bottom: 0.8rem;
        }

        .footer-links a {
            color: var(--text-gray);
            text-decoration: none;
            transition: color 0.3s;
        }

        .footer-links a:hover {
            color: var(--primary);
        }

        .social-links {
            display: flex;
            gap: 1rem;
            margin-top: 1rem;
        }

        .social-links a {
            width: 40px;
            height: 40px;
            background: var(--light-gray);
            border-radius: 50%;
            display: flex;
            align-items: center;
            justify-content: center;
            color: var(--white);
            text-decoration: none;
            transition: all 0.3s;
        }

        .social-links a:hover {
            background: var(--primary);
            color: var(--dark);
        }

        .copyright {
            text-align: center;
            padding-top: 2rem;
            border-top: 1px solid var(--light-gray);
            color: var(--text-gray);
        }

        /* Hidden Sections */
        .hidden {
            display: none;
        }

        /* Course Detail Styles */
        .course-detail {
            background: var(--gray);
            border-radius: 20px;
            padding: 1rem;
            border: 1px solid var(--light-gray);
            max-width: 900px;
            margin: 0 auto;
        }

        .course-detail h1 {
            font-size: 2.5rem;
            margin-bottom: 1rem;
            color: var(--white);
        }

        .instructor {
            color: var(--text-gray);
            margin-bottom: 2rem;
            font-size: 1.1rem;
        }

        .course-description {
            margin: 2rem 0;
            line-height: 1.8;
            color: var(--text-gray);
        }

        .price-section {
            display: flex;
            justify-content: space-between;
            align-items: center;
            padding: 1.5rem;
            background: var(--light-gray);
            border-radius: 12px;
            margin: 2rem 0;
        }

        .price-display {
                font-size: 2rem;
                font-weight: 800;
                color: var(--primary);
            }

            /* Course Content Collapsible Styles */
            .course-content-section {
                margin: 3rem 0;
                background: var(--light-gray);
                border-radius: 12px;
                overflow: hidden;
                border: 1px solid var(--light-gray);
            }

            .course-content-section h2 {
                padding: 1.5rem 2rem;
                background: var(--gray);
                margin: 0;
                font-size: 1.8rem;
                color: var(--white);
                border-bottom: 1px solid var(--light-gray);
            }

            details {
                border-bottom: 1px solid rgba(255, 255, 255, 0.1);
            }

            details:last-child {
                border-bottom: none;
            }

            summary {
                padding: 1.5rem 2rem;
                cursor: pointer;
                background: linear-gradient(135deg, var(--gray), var(--light-gray));
                transition: all 0.3s ease;
                font-weight: 600;
                color: var(--white);
                display: flex;
                justify-content: space-between;
                align-items: center;
                position: relative;
            }

            summary:hover {
                background: linear-gradient(135deg, var(--light-gray), var(--gray));
                color: var(--primary);
            }

            summary::-webkit-details-marker {
                display: none;
            }

            summary::after {
                content: '▶';
                font-size: 1rem;
                transition: transform 0.3s ease;
                color: var(--primary);
            }

            details[open] summary::after {
                transform: rotate(90deg);
            }

            .chapter-content {
                padding: 0 2rem 1.5rem;
                background: var(--gray);
                color: var(--text-gray);
                line-height: 1.6;
                max-height: 0;
                overflow: hidden;
                transition: max-height 0.3s ease, padding 0.3s ease;
            }

            details[open] .chapter-content {
                max-height: 300px; /* Increased for longer descriptions */
                padding: 1.5rem 2rem 1.5rem;
            }

            .chapter-content p {
                font-size: 1rem;
                line-height: 1.7;
                color: var(--text-gray);
                margin: 0;
                text-align: justify;
                background: rgba(255, 255, 255, 0.02);
                padding: 1rem;
                border-left: 3px solid var(--primary);
                border-radius: 0 8px 8px 0;
                transition: all 0.3s ease;
            }

            .chapter-content p:hover {
                background: rgba(10, 255, 157, 0.05);
                color: var(--white);
            }

            .chapter-number {
                font-size: 0.9rem;
                color: var(--primary);
                font-weight: 500;
                margin-left: auto;
            }

            /* Responsive for Collapsible */
            @media (max-width: 768px) {
                summary {
                    padding: 1.2rem 1.5rem;
                    font-size: 1rem;
                }

                .chapter-content {
                    padding: 1rem 1.5rem 1.2rem;
                }

                details[open] .chapter-content {
                    padding: 1.2rem 1.5rem 1.2rem;
                }
            }

            /* Responsive */
            @media (max-width: 768px) {
            .nav-links {
                position: fixed;
                top: 70px;
                left: -100%;
                flex-direction: column;
                background: var(--gray);
                width: 100%;
                padding: 2rem;
                gap: 1.5rem;
                transition: left 0.3s;
                border-bottom: 1px solid var(--light-gray);
            }

            .nav-links.active {
                left: 0;
            }

            .mobile-toggle {
                display: flex;
            }

            .hero h1 {
                font-size: 2.5rem;
            }

            .hero p {
                font-size: 1.1rem;
            }

            .section-header h2 {
                font-size: 2rem;
            }

            .course-grid {
                grid-template-columns: 1fr;
            }

            .price-section {
                flex-direction: column;
                gap: 1rem;
            }

            .price-display {
                font-size: 1.8rem;
            }
            
            .price-button {
                padding: 1rem 2rem;
                font-size: 1.1rem;
            }
        }