/* CSS Reset & Base */
        *, *::before, *::after {
            box-sizing: border-box;
            margin: 0;
            padding: 0;
        }

        :root {
            --primary-blue: #3b82f6;
            --deep-blue: #1d4ed8;
            --light-blue: #60a5fa;
            --accent-blue: #2563eb;
            --dark-blue: #1e3a8a;
            --text-primary: #ffffff;
            --text-secondary: #e5e7eb;
            --text-muted: #9ca3af;
            --background: #0f172a;
            --surface: #1e293b;
            --border: rgba(59, 130, 246, 0.2);
        }

        html {
            scroll-behavior: smooth;
            font-size: 16px;
        }

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

        /* Header */
        .header {
            position: fixed;
            top: 0;
            width: 100%;
            backdrop-filter: blur(10px);
            border-bottom: 1px solid var(--border);
            z-index: 1000;
            transition: all 0.3s ease;
            background: rgba(15, 23, 42, 0.9);
        }

        .nav {
            max-width: 1200px;
            margin: 0 auto;
            padding: 1rem 2rem;
            display: flex;
            align-items: center;
            justify-content: space-between;
        }

        .logo {
            display: flex;
            align-items: center;
            gap: 0.75rem;
            text-decoration: none;
            color: var(--text-primary);
        }

        .logo-img {
            width: auto;
            height: 60px;
            border-radius: 12px;
            object-fit: contain;
        }

        .logo-text {
            display: none;
        }

        .nav-links {
            display: flex;
            gap: 2rem;
            list-style: none;
        }

        .nav-link {
            color: var(--text-secondary);
            text-decoration: none;
            font-weight: 500;
            transition: color 0.3s ease;
        }

        .nav-link:hover {
            color: var(--primary-blue);
        }

        .cta-button {
            background: linear-gradient(135deg, var(--primary-blue), var(--deep-blue));
            color: white;
            padding: 0.75rem 1.5rem;
            border-radius: 0.5rem;
            text-decoration: none;
            font-weight: 600;
            transition: all 0.3s ease;
            border: none;
            cursor: pointer;
        }

        .cta-button:hover {
            transform: translateY(-2px);
            box-shadow: 0 8px 25px rgba(59, 130, 246, 0.3);
        }

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

        /* Hero Section */
        .tutorials-hero {
            padding: 120px 2rem 4rem;
            background: linear-gradient(135deg, #0f172a 0%, #1e293b 100%);
            text-align: center;
            position: relative;
            overflow: hidden;
        }

        .tutorials-hero::before {
            content: '';
            position: absolute;
            top: 0;
            left: 0;
            right: 0;
            bottom: 0;
            background-image: url('https://choloiptv.store/assets/img/bg4.jpg');
            background-repeat: no-repeat;
            background-size: cover;
            background-position: center;
            opacity: 0.1;
            z-index: 1;
        }

        .tutorials-container {
            max-width: 1200px;
            margin: 0 auto;
            position: relative;
            z-index: 2;
        }

        .hero-title {
            font-size: clamp(2.5rem, 5vw, 4rem);
            font-weight: 800;
            line-height: 1.1;
            margin-bottom: 1.5rem;
            background: linear-gradient(135deg, var(--text-primary), var(--light-blue));
            -webkit-background-clip: text;
            -webkit-text-fill-color: transparent;
            background-clip: text;
        }

        .hero-subtitle {
            font-size: 1.25rem;
            color: var(--text-secondary);
            margin-bottom: 2rem;
            line-height: 1.6;
            max-width: 800px;
            margin: 0 auto 2rem;
        }

        /* Apps Section */
        .apps-section {
            padding: 6rem 2rem;
            background: var(--surface);
        }

        .apps-container {
            max-width: 1400px;
            margin: 0 auto;
        }

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

        .section-title {
            font-size: clamp(2rem, 4vw, 3rem);
            font-weight: 700;
            margin-bottom: 1rem;
            color: var(--text-primary);
        }

        .section-subtitle {
            font-size: 1.25rem;
            color: var(--text-secondary);
            max-width: 600px;
            margin: 0 auto;
        }

        .category-section {
            margin-bottom: 5rem;
        }

        .category-header {
            display: flex;
            align-items: center;
            gap: 1rem;
            margin-bottom: 3rem;
            padding: 2rem;
            background: rgba(59, 130, 246, 0.05);
            border-radius: 1rem;
            border: 1px solid var(--border);
        }

        .category-icon {
            width: 80px;
            height: 80px;
            background: linear-gradient(135deg, var(--primary-blue), var(--deep-blue));
            border-radius: 1rem;
            display: flex;
            align-items: center;
            justify-content: center;
            font-size: 2.5rem;
            box-shadow: 0 8px 25px rgba(59, 130, 246, 0.3);
            flex-shrink: 0;
        }

        .category-info h3 {
            font-size: 2rem;
            font-weight: 700;
            color: var(--text-primary);
            margin-bottom: 0.5rem;
        }

        .category-info p {
            color: var(--text-secondary);
            font-size: 1.125rem;
        }

        .apps-grid {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
            gap: 2rem;
        }

        .app-card {
            background: rgba(59, 130, 246, 0.05);
            border: 1px solid var(--border);
            border-radius: 1rem;
            padding: 2rem;
            text-align: center;
            transition: all 0.3s ease;
            cursor: pointer;
            position: relative;
            overflow: hidden;
        }

        .app-card::before {
            content: '';
            position: absolute;
            top: 0;
            left: -100%;
            width: 100%;
            height: 100%;
            background: linear-gradient(90deg, transparent, rgba(59, 130, 246, 0.1), transparent);
            transition: left 0.5s;
        }

        .app-card:hover::before {
            left: 100%;
        }

        .app-card:hover {
            transform: translateY(-10px);
            border-color: var(--primary-blue);
            box-shadow: 0 20px 40px rgba(59, 130, 246, 0.2);
        }

        .app-status {
            display: inline-block;
            padding: 0.25rem 0.75rem;
            border-radius: 1rem;
            font-size: 0.75rem;
            font-weight: 600;
            margin-bottom: 1rem;
        }

        .status-recommended {
            background: rgba(34, 197, 94, 0.1);
            color: #22c55e;
            border: 1px solid rgba(34, 197, 94, 0.3);
        }

        .status-popular {
            background: rgba(245, 158, 11, 0.1);
            color: #f59e0b;
            border: 1px solid rgba(245, 158, 11, 0.3);
        }

        .status-free {
            background: rgba(59, 130, 246, 0.1);
            color: var(--primary-blue);
            border: 1px solid rgba(59, 130, 246, 0.3);
        }

        .app-icon {
            width: 70px;
            height: 70px;
            margin: 0 auto 1rem;
            background: linear-gradient(135deg, var(--primary-blue), var(--deep-blue));
            border-radius: 1rem;
            display: flex;
            align-items: center;
            justify-content: center;
            font-size: 1.75rem;
            transition: all 0.3s ease;
            box-shadow: 0 6px 20px rgba(59, 130, 246, 0.3);
        }

        .app-card:hover .app-icon {
            transform: scale(1.1) rotate(5deg);
        }

        .app-name {
            font-size: 1.25rem;
            font-weight: 600;
            color: var(--text-primary);
            margin-bottom: 0.5rem;
        }

        .app-rating {
            display: flex;
            align-items: center;
            justify-content: center;
            gap: 0.5rem;
            margin: 1rem 0;
        }

        .rating-stars {
            color: #fbbf24;
            font-size: 0.875rem;
        }

        .rating-score {
            color: var(--text-muted);
            font-size: 0.875rem;
            font-weight: 500;
        }

        .app-features {
            list-style: none;
            margin: 1rem 0;
            text-align: left;
        }

        .app-feature {
            color: var(--text-secondary);
            font-size: 0.875rem;
            padding: 0.25rem 0;
            display: flex;
            align-items: center;
            gap: 0.5rem;
        }

        .app-feature::before {
            content: '✓';
            color: var(--primary-blue);
            font-weight: bold;
            font-size: 0.75rem;
        }

        .compatibility-badges {
            display: flex;
            gap: 0.5rem;
            justify-content: center;
            margin: 1rem 0;
            flex-wrap: wrap;
        }

        .compatibility-badge {
            background: rgba(168, 85, 247, 0.1);
            color: #a855f7;
            padding: 0.25rem 0.5rem;
            border-radius: 0.5rem;
            font-size: 0.7rem;
            font-weight: 600;
            border: 1px solid rgba(168, 85, 247, 0.2);
        }

        .setup-btn {
            background: linear-gradient(135deg, var(--primary-blue), var(--deep-blue));
            color: white;
            padding: 0.75rem 1.5rem;
            border-radius: 0.5rem;
            text-decoration: none;
            font-weight: 600;
            transition: all 0.3s ease;
            display: inline-block;
            font-size: 0.875rem;
            width: 100%;
            border: none;
            cursor: pointer;
        }

        .setup-btn:hover {
            transform: translateY(-2px);
            box-shadow: 0 8px 25px rgba(59, 130, 246, 0.4);
        }

        /* Tutorial Modal */
        .tutorial-modal {
            display: none;
            position: fixed;
            top: 0;
            left: 0;
            width: 100%;
            height: 100%;
            background: rgba(0, 0, 0, 0.9);
            z-index: 10000;
            overflow-y: auto;
            animation: fadeIn 0.3s ease;
            backdrop-filter: blur(5px);
        }

        @keyframes fadeIn {
            from { opacity: 0; }
            to { opacity: 1; }
        }

        .modal-content {
            max-width: 900px;
            margin: 2rem auto;
            background: var(--surface);
            border-radius: 1rem;
            position: relative;
            box-shadow: 0 20px 60px rgba(0, 0, 0, 0.5);
            animation: slideIn 0.3s ease;
            border: 1px solid var(--border);
        }

        @keyframes slideIn {
            from { 
                transform: translateY(-30px);
                opacity: 0;
            }
            to { 
                transform: translateY(0);
                opacity: 1;
            }
        }

        .modal-header {
            padding: 2rem 2rem 1rem;
            border-bottom: 1px solid var(--border);
            display: flex;
            justify-content: space-between;
            align-items: center;
            background: linear-gradient(135deg, rgba(59, 130, 246, 0.1), transparent);
            border-radius: 1rem 1rem 0 0;
        }

        .modal-title {
            font-size: 1.75rem;
            font-weight: 700;
            color: var(--text-primary);
            display: flex;
            align-items: center;
            gap: 0.5rem;
        }

        .close-btn {
            background: none;
            border: none;
            font-size: 2rem;
            color: var(--text-muted);
            cursor: pointer;
            padding: 0.5rem;
            border-radius: 0.5rem;
            transition: all 0.3s ease;
            width: 50px;
            height: 50px;
            display: flex;
            align-items: center;
            justify-content: center;
        }

        .close-btn:hover {
            background: rgba(239, 68, 68, 0.1);
            color: #ef4444;
            transform: rotate(90deg);
        }

        .tutorial-content {
            padding: 2rem;
        }

        .app-header {
            display: flex;
            align-items: center;
            gap: 1rem;
            margin-bottom: 2rem;
            padding: 1rem;
            background: rgba(59, 130, 246, 0.05);
            border-radius: 0.75rem;
            border: 1px solid var(--border);
        }

        .app-header-logo {
            width: 60px;
            height: 60px;
            background: linear-gradient(135deg, var(--primary-blue), var(--deep-blue));
            border-radius: 0.75rem;
            display: flex;
            align-items: center;
            justify-content: center;
            font-size: 1.5rem;
            flex-shrink: 0;
            box-shadow: 0 4px 15px rgba(59, 130, 246, 0.3);
        }

        .app-header-info h3 {
            color: var(--text-primary);
            font-size: 1.5rem;
            margin-bottom: 0.25rem;
            font-weight: 600;
        }

        .app-header-info p {
            color: var(--text-secondary);
            font-size: 0.875rem;
            line-height: 1.4;
        }

        .download-section {
            background: rgba(34, 197, 94, 0.1);
            border: 1px solid rgba(34, 197, 94, 0.3);
            border-radius: 0.75rem;
            padding: 1.5rem;
            margin-bottom: 2rem;
        }

        .download-title {
            color: #22c55e;
            font-weight: 600;
            margin-bottom: 1rem;
            display: flex;
            align-items: center;
            gap: 0.5rem;
            font-size: 1.125rem;
        }

        .download-links {
            display: flex;
            gap: 1rem;
            flex-wrap: wrap;
        }

        .download-btn {
            display: flex;
            align-items: center;
            gap: 0.5rem;
            background: #22c55e;
            color: white;
            padding: 0.75rem 1.25rem;
            border-radius: 0.5rem;
            text-decoration: none;
            font-weight: 600;
            font-size: 0.875rem;
            transition: all 0.3s ease;
            border: none;
            cursor: pointer;
        }

        .download-btn:hover {
            background: #16a34a;
            transform: translateY(-2px);
            box-shadow: 0 4px 15px rgba(34, 197, 94, 0.3);
        }

        .setup-steps {
            counter-reset: step-counter;
        }

        .setup-step {
            position: relative;
            padding-left: 4rem;
            margin-bottom: 3rem;
            padding-bottom: 2rem;
            border-bottom: 1px solid var(--border);
        }

        .setup-step:last-child {
            border-bottom: none;
            margin-bottom: 0;
        }

        .setup-step::before {
            counter-increment: step-counter;
            content: counter(step-counter);
            position: absolute;
            left: 0;
            top: 0;
            width: 50px;
            height: 50px;
            background: linear-gradient(135deg, var(--primary-blue), var(--deep-blue));
            color: white;
            border-radius: 50%;
            display: flex;
            align-items: center;
            justify-content: center;
            font-weight: 700;
            font-size: 1.25rem;
            box-shadow: 0 4px 15px rgba(59, 130, 246, 0.3);
            z-index: 2;
        }

        .setup-step::after {
            content: '';
            position: absolute;
            left: 24px;
            top: 60px;
            width: 2px;
            height: calc(100% - 40px);
            background: linear-gradient(to bottom, var(--primary-blue), transparent);
            z-index: 1;
        }

        .setup-step:last-child::after {
            display: none;
        }

        .step-title {
            font-size: 1.25rem;
            font-weight: 600;
            color: var(--text-primary);
            margin-bottom: 1rem;
            line-height: 1.3;
        }

        .step-content {
            color: var(--text-secondary);
            line-height: 1.6;
            margin-bottom: 1.5rem;
        }

        .step-content p {
            margin-bottom: 1rem;
        }

        .step-content ul {
            margin: 1rem 0;
            padding-left: 1.5rem;
        }

        .step-content li {
            margin-bottom: 0.5rem;
            color: var(--text-secondary);
        }

        .step-image {
            width: 100%;
            max-width: 500px;
            height: auto;
            border-radius: 0.75rem;
            border: 1px solid var(--border);
            margin: 1rem 0;
            box-shadow: 0 8px 25px rgba(0, 0, 0, 0.1);
            transition: all 0.3s ease;
        }

        .step-image:hover {
            transform: scale(1.02);
            box-shadow: 0 12px 35px rgba(59, 130, 246, 0.2);
        }

        .step-tip {
            background: rgba(245, 158, 11, 0.1);
            border: 1px solid rgba(245, 158, 11, 0.3);
            border-radius: 0.5rem;
            padding: 1rem;
            margin: 1rem 0;
            color: var(--text-primary);
            font-size: 0.875rem;
            line-height: 1.5;
        }

        .step-tip::before {
            content: '💡 ';
            margin-right: 0.5rem;
        }

        .credential-box {
            background: rgba(168, 85, 247, 0.1);
            border: 1px solid rgba(168, 85, 247, 0.3);
            border-radius: 0.75rem;
            padding: 1.5rem;
            margin: 1.5rem 0;
        }

        .credential-title {
            color: #a855f7;
            font-weight: 600;
            margin-bottom: 1rem;
            display: flex;
            align-items: center;
            gap: 0.5rem;
            font-size: 1.125rem;
        }

        .credential-info {
            color: var(--text-secondary);
            line-height: 1.6;
        }

        .credential-info p {
            margin-bottom: 0.5rem;
            padding: 0.25rem 0;
        }

        .credential-info strong {
            color: var(--text-primary);
            display: inline-block;
            min-width: 120px;
        }

        /* Customer Service Banner */
        .customer-service-banner {
            background: var(--background);
            border-top: 1px solid var(--border);
            border-bottom: 1px solid var(--border);
            padding: 3rem 2rem;
        }

        .banner-container {
            max-width: 1200px;
            margin: 0 auto;
            display: flex;
            align-items: center;
            gap: 2rem;
            background: rgba(59, 130, 246, 0.05);
            border: 1px solid var(--border);
            border-radius: 1rem;
            padding: 2rem;
        }

        .banner-icon {
            font-size: 3rem;
            background: linear-gradient(135deg, var(--primary-blue), var(--deep-blue));
            width: 70px;
            height: 70px;
            border-radius: 50%;
            display: flex;
            align-items: center;
            justify-content: center;
            flex-shrink: 0;
            box-shadow: 0 8px 25px rgba(59, 130, 246, 0.3);
        }

        .banner-info {
            flex: 1;
        }

        .banner-info h3 {
            font-size: 1.5rem;
            font-weight: 700;
            color: var(--text-primary);
            margin-bottom: 0.25rem;
        }

        .banner-info p {
            color: var(--text-secondary);
            font-size: 1rem;
        }

        .banner-buttons {
            display: flex;
            gap: 1rem;
        }

        .support-btn {
            display: flex;
            align-items: center;
            gap: 0.5rem;
            padding: 0.75rem 1.5rem;
            border-radius: 0.5rem;
            font-weight: 600;
            text-decoration: none;
            transition: all 0.3s ease;
            font-size: 0.95rem;
        }

        .support-btn.whatsapp {
            background: #25d366;
            color: white;
        }

        .support-btn.whatsapp:hover {
            background: #20b954;
            transform: translateY(-2px);
            box-shadow: 0 4px 15px rgba(37, 211, 102, 0.3);
        }

        .support-btn.email {
            background: var(--primary-blue);
            color: white;
        }

        .support-btn.email:hover {
            background: var(--deep-blue);
            transform: translateY(-2px);
            box-shadow: 0 4px 15px rgba(59, 130, 246, 0.3);
        }

        /* Footer */
        .footer {
            background: var(--surface);
            padding: 3rem 2rem 1rem;
            border-top: 1px solid var(--border);
        }

        .footer-bottom {
            border-top: 1px solid var(--border);
            text-align: center;
            color: var(--text-muted);
            padding-top: 1rem;
        }

        /* Responsive Design */
        @media (max-width: 1024px) {
            .apps-grid {
                grid-template-columns: repeat(2, 1fr);
                gap: 1.5rem;
            }
        }

        @media (max-width: 768px) {
            .nav-links {
                display: none;
                position: absolute;
                top: 100%;
                left: 0;
                right: 0;
                background: rgba(15, 23, 42, 0.98);
                backdrop-filter: blur(10px);
                flex-direction: column;
                padding: 1rem;
                border-top: 1px solid var(--border);
            }

            .nav-links.active {
                display: flex;
            }

            .mobile-menu-toggle {
                display: block;
            }

            .cta-button {
                display: none;
            }

            .tutorials-hero {
                padding: 100px 1rem 3rem;
            }

            .apps-section {
                padding: 4rem 1rem;
            }

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

            .modal-content {
                margin: 1rem;
                border-radius: 0.5rem;
                max-height: calc(100vh - 2rem);
                overflow-y: auto;
            }

            .modal-header,
            .tutorial-content {
                padding: 1.5rem;
            }

            .banner-container {
                flex-direction: column;
                text-align: center;
                gap: 1.5rem;
            }

            .banner-buttons {
                width: 100%;
                justify-content: center;
            }

            .setup-step {
                padding-left: 3rem;
            }

            .setup-step::before {
                width: 40px;
                height: 40px;
                font-size: 1rem;
            }

            .setup-step::after {
                left: 19px;
            }

            .step-image {
                max-width: 100%;
            }

            .logo-img {
                height: 50px;
            }

            .category-header {
                flex-direction: column;
                text-align: center;
                gap: 1.5rem;
            }

            .category-icon {
                width: 70px;
                height: 70px;
                font-size: 2rem;
            }
        }

        @media (max-width: 480px) {
            .banner-buttons {
                flex-direction: column;
                width: 100%;
            }

            .support-btn {
                justify-content: center;
                width: 100%;
            }

            .hero-title {
                font-size: 2rem;
            }

            .hero-subtitle {
                font-size: 1rem;
            }

            .app-card {
                padding: 1.5rem;
            }

            .app-icon {
                width: 60px;
                height: 60px;
                font-size: 1.5rem;
            }

            .modal-header {
                padding: 1rem;
                flex-direction: column;
                gap: 1rem;
                text-align: center;
            }

            .modal-title {
                font-size: 1.25rem;
            }

            .tutorial-content {
                padding: 1rem;
            }

            .setup-step {
                margin-bottom: 2rem;
                padding-bottom: 1.5rem;
                padding-left: 2.5rem;
            }

            .setup-step::before {
                width: 35px;
                height: 35px;
                font-size: 0.875rem;
            }

            .setup-step::after {
                left: 16.5px;
            }

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

            .download-links {
                flex-direction: column;
            }

            .download-btn {
                justify-content: center;
            }

            .category-info h3 {
                font-size: 1.5rem;
            }

            .section-title {
                font-size: 1.75rem;
            }
        }

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

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

        ::-webkit-scrollbar-thumb {
            background: var(--primary-blue);
            border-radius: 4px;
        }

        ::-webkit-scrollbar-thumb:hover {
            background: var(--deep-blue);
        }

        /* Focus States for Accessibility */
        .app-card:focus,
        .setup-btn:focus,
        .download-btn:focus,
        .support-btn:focus,
        .close-btn:focus {
            outline: 2px solid var(--primary-blue);
            outline-offset: 2px;
        }

        /* Print Styles */
        @media print {
            .header,
            .customer-service-banner,
            .footer,
            .tutorial-modal {
                display: none;
            }
            
            .tutorials-hero,
            .apps-section {
                page-break-inside: avoid;
            }
        }