@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700;800;900&display=swap');
        
        * {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
        }

        :root {
            --primary: #6366f1;
            --primary-dark: #4f46e5;
            --secondary: #10b981;
            --accent: #f59e0b;
            --success: #22c55e;
            --danger: #ef4444;
            --dark: #1f2937;
            --gray-50: #f9fafb;
            --gray-100: #f3f4f6;
            --gray-200: #e5e7eb;
            --gray-300: #d1d5db;
            --gray-600: #4b5563;
            --gray-800: #1f2937;
            --gray-900: #111827;
            --white: #ffffff;
            --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
            --shadow: 0 1px 3px 0 rgb(0 0 0 / 0.1), 0 1px 2px -1px rgb(0 0 0 / 0.1);
            --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
            --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.1), 0 4px 6px -4px rgb(0 0 0 / 0.1);
            --shadow-xl: 0 20px 25px -5px rgb(0 0 0 / 0.1), 0 8px 10px -6px rgb(0 0 0 / 0.1);
        }

        html {
            scroll-behavior: smooth;
        }

        body {
            font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
            line-height: 1.6;
            color: var(--gray-800);
            overflow-x: hidden;
        }

        /* Header Styles */
        header {
            position: fixed;
            top: 0;
            left: 0;
            right: 0;
            background: rgba(255, 255, 255, 0.95);
            backdrop-filter: blur(20px);
            z-index: 1000;
            padding: 1rem 2rem;
            border-bottom: 1px solid rgba(255, 255, 255, 0.2);
            box-shadow: var(--shadow-sm);
            display: flex;
            justify-content: space-between;
            align-items: center;
            transition: all 0.3s ease;
        }

        .logo {
            display: flex;
            align-items: center;
            gap: 0.75rem;
        }

        .logo img {
            height: 40px;
            width: 40px;
            border-radius: 8px;
            filter: brightness(1.1);
        }

        .logo::after {
            content: 'LearnHub';
            font-size: 1.5rem;
            font-weight: 800;
            background: linear-gradient(135deg, var(--primary), var(--secondary));
            -webkit-background-clip: text;
            -webkit-text-fill-color: transparent;
            background-clip: text;
        }

        .menu-toggle {
            display: none;
            background: none;
            border: none;
            font-size: 1.5rem;
            cursor: pointer;
            color: var(--gray-700);
        }

        nav ul {
            display: flex;
            list-style: none;
            gap: 2rem;
            align-items: center;
        }

        nav ul li a {
            text-decoration: none;
            color: var(--gray-600);
            font-weight: 500;
            padding: 0.5rem 1rem;
            border-radius: 8px;
            transition: all 0.3s ease;
            position: relative;
        }

        nav ul li a:hover {
            color: var(--primary);
            background: rgba(99, 102, 241, 0.1);
            transform: translateY(-1px);
        }

        nav ul li a::after {
            content: '';
            position: absolute;
            bottom: -2px;
            left: 50%;
            width: 0;
            height: 2px;
            background: linear-gradient(90deg, var(--primary), var(--secondary));
            transition: all 0.3s ease;
            transform: translateX(-50%);
        }

        nav ul li a:hover::after {
            width: 80%;
        }

        .auth-buttons {
            display: flex;
            gap: 1rem;
            align-items: center;
        }

        .auth-buttons a {
            text-decoration: none;
        }

        .login-btn, .signup-btn {
            padding: 0.75rem 1.5rem;
            border: none;
            border-radius: 25px;
            font-weight: 600;
            cursor: pointer;
            transition: all 0.3s ease;
            font-size: 0.95rem;
        }

        .login-btn {
            background: transparent;
            color: var(--gray-600);
            border: 2px solid var(--gray-300);
        }

        .login-btn:hover {
            background: var(--gray-100);
            border-color: var(--primary);
            color: var(--primary);
            transform: translateY(-2px);
        }

        .signup-btn {
            background: linear-gradient(135deg, var(--primary), var(--primary-dark));
            color: white;
            box-shadow: var(--shadow);
        }

        .signup-btn:hover {
            background: linear-gradient(135deg, var(--primary-dark), #3730a3);
            transform: translateY(-2px);
            box-shadow: var(--shadow-lg);
        }

        /* Hero Section */
        .hero {
            min-height: 20vh;
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
            display: flex;
            align-items: center;
            justify-content: center;
            text-align: center;
            color: white;
            position: relative;
            overflow: hidden;
        }

        .hero::before {
            content: '';
            position: absolute;
            top: 0;
            left: 0;
            right: 0;
            bottom: 0;
            background: url('data:image/svg+xml,<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 1000 1000" opacity="0.1"><defs><radialGradient id="a" cx="50%" cy="50%" r="50%"><stop offset="0%" style="stop-color:white"/><stop offset="100%" style="stop-color:transparent"/></radialGradient></defs><circle cx="200" cy="200" r="100" fill="url(%23a)"/><circle cx="800" cy="300" r="150" fill="url(%23a)"/><circle cx="400" cy="700" r="120" fill="url(%23a)"/><circle cx="700" cy="800" r="80" fill="url(%23a)"/></svg>') no-repeat center;
            background-size: cover;
            animation: float 20s ease-in-out infinite;
        }

        @keyframes float {
            0%, 100% { transform: translateY(0px); }
            50% { transform: translateY(-20px); }
        }

        .hero-text {
            max-width: 800px;
            padding: 0 2rem;
            position: relative;
            z-index: 10;
        }

        .hero-text h1 {
            font-size: 4rem;
            font-weight: 900;
            margin-bottom: 1.5rem;
            text-shadow: 0 4px 8px rgba(0, 0, 0, 0.3);
            animation: fadeInUp 1s ease-out;
            background: linear-gradient(135deg, #ffffff, #f0f9ff);
            -webkit-background-clip: text;
            -webkit-text-fill-color: transparent;
            background-clip: text;
        }

        .hero-text p {
            font-size: 1.5rem;
            opacity: 0.95;
            margin-bottom: 2rem;
            animation: fadeInUp 1s ease-out 0.3s both;
            text-shadow: 0 2px 4px rgba(0, 0, 0, 0.2);
        }

        @keyframes fadeInUp {
            from {
                opacity: 0;
                transform: translateY(50px);
            }
            to {
                opacity: 1;
                transform: translateY(0);
            }
        }

        /* Sections */
        section {
            padding: 5rem 2rem;
            max-width: 1200px;
            margin: 0 auto;
        }

        section h2 {
            text-align: center;
            font-size: 2.5rem;
            font-weight: 700;
            margin-bottom: 3rem;
            color: var(--gray-800);
            position: relative;
        }

        section h2::after {
            content: '';
            position: absolute;
            bottom: -10px;
            left: 50%;
            width: 60px;
            height: 4px;
            background: linear-gradient(90deg, var(--primary), var(--secondary));
            transform: translateX(-50%);
            border-radius: 2px;
        }

        /* Featured Courses */
        .featured-courses {
            background: linear-gradient(135deg, rgba(99, 102, 241, 0.05), rgba(16, 185, 129, 0.05));
        }

        .courses-grid {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
            gap: 2rem;
        }

        .course-card {
            background: white;
            padding: 2.5rem;
            border-radius: 20px;
            box-shadow: var(--shadow-lg);
            text-align: center;
            transition: all 0.4s cubic-bezier(0.4, 0, 0.2, 1);
            border: 1px solid rgba(255, 255, 255, 0.2);
            position: relative;
            overflow: hidden;
        }

        .course-card::before {
            content: '';
            position: absolute;
            top: 0;
            left: 0;
            right: 0;
            height: 4px;
            background: linear-gradient(90deg, var(--primary), var(--secondary), var(--accent));
        }

        .course-card:hover {
            transform: translateY(-10px) scale(1.02);
            box-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.25);
        }

        .course-card h3 {
            font-size: 1.5rem;
            font-weight: 600;
            margin-bottom: 1rem;
            color: var(--gray-800);
        }

        .course-card p {
            color: var(--gray-600);
            line-height: 1.8;
            font-size: 1.1rem;
        }

        /* Categories */
        .categories {
            background: white;
        }

        .categories-grid {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
            gap: 1.5rem;
        }

        .category {
            background: linear-gradient(135deg, rgba(99, 102, 241, 0.1), rgba(16, 185, 129, 0.1));
            padding: 2rem 1.5rem;
            border-radius: 15px;
            text-align: center;
            font-weight: 600;
            color: var(--gray-800);
            transition: all 0.3s ease;
            border: 2px solid transparent;
            cursor: pointer;
        }

        .category:hover {
            transform: translateY(-5px);
            background: linear-gradient(135deg, var(--primary), var(--secondary));
            color: white;
            box-shadow: var(--shadow-lg);
        }

        /* About Section */
        .about {
            background: linear-gradient(135deg, rgba(245, 158, 11, 0.05), rgba(239, 68, 68, 0.05));
            text-align: center;
        }

        .about p {
            font-size: 1.2rem;
            line-height: 1.8;
            color: var(--gray-600);
            margin-bottom: 1.5rem;
            max-width: 800px;
            margin-left: auto;
            margin-right: auto;
        }

        /* Testimonials */
        .testimonials {
            background: white;
        }

        .testimonial {
            background: linear-gradient(135deg, rgba(255, 255, 255, 0.9), rgba(255, 255, 255, 0.7));
            backdrop-filter: blur(20px);
            padding: 2.5rem;
            border-radius: 20px;
            box-shadow: var(--shadow-lg);
            margin-bottom: 2rem;
            border: 1px solid rgba(255, 255, 255, 0.2);
            display: flex;
            align-items: center;
            gap: 2rem;
            transition: all 0.3s ease;
        }

        .testimonial:hover {
            transform: translateX(10px);
            box-shadow: var(--shadow-xl);
        }

        .testimonial-profile {
            flex-shrink: 0;
        }

        .placeholder {
            width: 60px;
            height: 60px;
            background: linear-gradient(135deg, var(--primary), var(--secondary));
            border-radius: 50%;
            display: flex;
            align-items: center;
            justify-content: center;
            color: white;
            font-weight: 600;
            font-size: 1.5rem;
        }

        .testimonial p {
            font-size: 1.1rem;
            line-height: 1.6;
            color: var(--gray-700);
            font-style: italic;
        }

        .testimonial strong {
            color: var(--primary);
            font-weight: 600;
        }

        /* Contact Section */
        .contact {
            background: linear-gradient(135deg, rgba(99, 102, 241, 0.05), rgba(16, 185, 129, 0.05));
            text-align: center;
        }

        .contact p {
            font-size: 1.2rem;
            color: var(--gray-600);
            margin-bottom: 3rem;
        }

        #contact-form {
            max-width: 600px;
            margin: 0 auto;
            display: flex;
            flex-direction: column;
            gap: 1.5rem;
        }

        #contact-form input,
        #contact-form textarea {
            padding: 1rem 1.5rem;
            border: 2px solid var(--gray-200);
            border-radius: 15px;
            font-size: 1rem;
            transition: all 0.3s ease;
            background: white;
            font-family: inherit;
        }

        #contact-form input:focus,
        #contact-form textarea:focus {
            outline: none;
            border-color: var(--primary);
            box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.1);
            transform: translateY(-2px);
        }

        #contact-form textarea {
            min-height: 120px;
            resize: vertical;
        }

        #contact-form button {
            background: linear-gradient(135deg, var(--primary), var(--primary-dark));
            color: white;
            padding: 1rem 2rem;
            border: none;
            border-radius: 25px;
            font-size: 1.1rem;
            font-weight: 600;
            cursor: pointer;
            transition: all 0.3s ease;
            box-shadow: var(--shadow);
        }

        #contact-form button:hover {
            background: linear-gradient(135deg, var(--primary-dark), #3730a3);
            transform: translateY(-2px);
            box-shadow: var(--shadow-lg);
        }

        /* Footer */
        footer {
            background: var(--gray-900);
            color: white;
            text-align: center;
            padding: 3rem 2rem;
            margin-top: 0;
        }

        footer p {
            margin-bottom: 2rem;
            opacity: 0.8;
        }

        .social-icons {
            display: flex;
            justify-content: center;
            gap: 1.5rem;
        }

        .social-icons a {
            display: inline-flex;
            align-items: center;
            justify-content: center;
            width: 50px;
            height: 50px;
            background: linear-gradient(135deg, var(--primary), var(--secondary));
            border-radius: 12px;
            transition: all 0.3s ease;
            text-decoration: none;
        }

        .social-icons a:hover {
            transform: translateY(-3px) scale(1.1);
            box-shadow: var(--shadow-lg);
        }

        .social-icons img {
            width: 24px;
            height: 24px;
            filter: brightness(0) invert(1);
        }

        /* Responsive Design */
        @media (max-width: 768px) {
            .menu-toggle {
                display: block;
            }

            nav ul {
                position: absolute;
                top: 100%;
                left: 0;
                right: 0;
                background: rgba(255, 255, 255, 0.98);
                backdrop-filter: blur(20px);
                flex-direction: column;
                padding: 2rem;
                box-shadow: var(--shadow-lg);
                transform: translateY(-100%);
                opacity: 0;
                visibility: hidden;
                transition: all 0.3s ease;
            }

            nav ul.show {
                transform: translateY(0);
                opacity: 1;
                visibility: visible;
            }

            .auth-buttons {
                display: none;
            }

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

            .hero-text p {
                font-size: 1.2rem;
            }

            section {
                padding: 3rem 1rem;
            }

            .courses-grid {
                grid-template-columns: 1fr;
                gap: 1.5rem;
            }

            .categories-grid {
                grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
            }

            .testimonial {
                flex-direction: column;
                text-align: center;
                gap: 1rem;
            }
        }

        /* Scroll animations */
        @keyframes slideInLeft {
            from {
                opacity: 0;
                transform: translateX(-50px);
            }
            to {
                opacity: 1;
                transform: translateX(0);
            }
        }

        @keyframes slideInRight {
            from {
                opacity: 0;
                transform: translateX(50px);
            }
            to {
                opacity: 1;
                transform: translateX(0);
            }
        }

        /* Custom scrollbar */
        ::-webkit-scrollbar {
            width: 8px;
        }

        ::-webkit-scrollbar-track {
            background: var(--gray-100);
        }

        ::-webkit-scrollbar-thumb {
            background: linear-gradient(135deg, var(--primary), var(--secondary));
            border-radius: 4px;
        }

        ::-webkit-scrollbar-thumb:hover {
            background: linear-gradient(135deg, var(--primary-dark), #059669);
        }

        /* Floating action elements */
        .floating-elements {
            position: absolute;
            top: 0;
            left: 0;
            width: 100%;
            height: 100%;
            pointer-events: none;
            overflow: hidden;
        }

        .floating-elements::before,
        .floating-elements::after {
            content: '';
            position: absolute;
            border-radius: 50%;
            background: rgba(255, 255, 255, 0.1);
            animation: float 8s ease-in-out infinite;
        }

        .floating-elements::before {
            width: 100px;
            height: 100px;
            top: 20%;
            left: 10%;
            animation-delay: -2s;
        }

        .floating-elements::after {
            width: 60px;
            height: 60px;
            top: 60%;
            right: 15%;
            animation-delay: -4s;
        }