:root {
            --primary: #FF0000;
            --primary-dark: #CC0000;
            --primary-light: rgba(255, 0, 0, 0.1);
            --secondary: #4285F4;
            --success: #34A853;
            --warning: #FBBC05;
            --danger: #EA4335;
            --light: #f8f9fa;
            --dark: #212529;
            --dark-gray: #343a40;
            --gray: #6c757d;
            --light-gray: #e9ecef;
            --bg-gradient: linear-gradient(135deg, #FF0000 0%, #FF6B6B 100%);
            --bg-gradient-hover: linear-gradient(135deg, #CC0000 0%, #FF5252 100%);
            --shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
            --shadow-hover: 0 8px 15px rgba(0, 0, 0, 0.15);
            --transition: all 0.3s cubic-bezier(0.25, 0.8, 0.25, 1);
            --border-radius: 12px;
            --border-radius-sm: 8px;
        }
        
        * {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
        }
        
        body {
            font-family: 'Poppins', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
            background-color: var(--light);
            color: var(--dark);
            line-height: 1.6;
            display: flex;
            flex-direction: column;
            min-height: 100vh;
            -webkit-font-smoothing: antialiased;
            -moz-osx-font-smoothing: grayscale;
        }
        
        /* Header Styles */
        header {
            background: var(--dark);
            color: white;
            padding: 1rem 0;
            box-shadow: var(--shadow);
            position: sticky;
            top: 0;
            z-index: 1000;
            border-bottom: 1px solid rgba(255, 255, 255, 0.1);
        }
        
        .header-container {
            display: flex;
            justify-content: space-between;
            align-items: center;
            max-width: 1200px;
            margin: 0 auto;
            padding: 0 2rem;
            width: 100%;
        }
        
        .logo {
            display: flex;
            align-items: center;
            font-size: 1.8rem;
            font-weight: 700;
            text-decoration: none;
            color: white;
            transition: var(--transition);
        }
        
        .logo i {
            margin-right: 10px;
            font-size: 2rem;
            color: var(--primary);
        }
        
        .logo:hover {
            transform: translateY(-2px);
        }
        
        .nav-toggle {
            background: none;
            border: none;
            color: white;
            font-size: 1.5rem;
            cursor: pointer;
            display: none;
            padding: 0.5rem;
            border-radius: 4px;
            transition: var(--transition);
        }
        
        .nav-toggle:hover {
            background: rgba(255, 255, 255, 0.1);
        }
        
        .nav-menu {
            display: flex;
            list-style: none;
        }
        
        .nav-menu li {
            margin-left: 1.5rem;
        }
        
        .nav-menu a {
            color: white;
            text-decoration: none;
            font-weight: 500;
            transition: var(--transition);
            padding: 0.5rem 1rem;
            border-radius: var(--border-radius-sm);
            display: flex;
            align-items: center;
        }
        
        .nav-menu a i {
            margin-right: 8px;
            font-size: 0.9rem;
        }
        
        .nav-menu a:hover {
            background-color: var(--primary);
            color: white;
        }
        
        .nav-menu a.active {
            background-color: var(--primary);
            color: white;
        }
        
        /* Main Content */
        main {
            flex: 1;
            display: flex;
            flex-direction: column;
            align-items: center;
            padding: 2rem 1rem;
            width: 100%;
        }
        
        .container {
            width: 100%;
            max-width: 900px;
            background: white;
            border-radius: var(--border-radius);
            box-shadow: var(--shadow);
            overflow: hidden;
            margin-bottom: 2rem;
            transition: var(--transition);
        }
        
        .container:hover {
            box-shadow: 0 10px 25px rgba(0, 0, 0, 0.15);
        }
        
        .hero {
            background: var(--bg-gradient);
            color: white;
            padding: 3rem 2rem;
            text-align: center;
            position: relative;
            overflow: hidden;
        }
        
        .hero::before {
            content: '';
            position: absolute;
            top: -50%;
            left: -50%;
            width: 200%;
            height: 200%;
            background: radial-gradient(circle, rgba(255,255,255,0.1) 0%, rgba(255,255,255,0) 70%);
            transform: rotate(30deg);
            z-index: 1;
        }
        
        .hero-content {
            position: relative;
            z-index: 2;
        }
        
        .hero h1 {
            font-size: 2.5rem;
            margin-bottom: 1rem;
            font-weight: 700;
            text-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
        }
        
        .hero p {
            font-size: 1.1rem;
            opacity: 0.9;
            max-width: 700px;
            margin: 0 auto;
        }
        
        .converter-section {
            padding: 2.5rem 2rem;
        }
        
        .input-group {
            display: flex;
            margin-bottom: 1.5rem;
            border-radius: 50px;
            overflow: hidden;
            box-shadow: 0 4px 15px rgba(0, 0, 0, 0.1);
            transition: var(--transition);
            border: 1px solid var(--light-gray);
        }
        
        .input-group:focus-within {
            border-color: var(--primary);
            box-shadow: 0 0 0 3px var(--primary-light);
        }
        
        #youtube-url {
            flex: 1;
            padding: 1.1rem 1.5rem;
            border: none;
            font-size: 1rem;
            outline: none;
            background: white;
            color: var(--dark);
        }
        
        #youtube-url::placeholder {
            color: var(--gray);
            opacity: 0.7;
        }
        
        #convert-btn {
            background: var(--bg-gradient);
            color: white;
            border: none;
            padding: 0 2.5rem;
            font-size: 1rem;
            font-weight: 600;
            cursor: pointer;
            transition: var(--transition);
            display: flex;
            align-items: center;
            justify-content: center;
            min-width: 150px;
        }
        
        #convert-btn i {
            margin-right: 8px;
        }
        
        #convert-btn:hover {
            background: var(--bg-gradient-hover);
            padding: 0 2.8rem;
        }
        
        #convert-btn:disabled {
            background: var(--gray);
            cursor: not-allowed;
            padding: 0 2.5rem;
        }
        
        .video-info {
            display: none;
            margin-top: 2rem;
            text-align: center;
            animation: fadeIn 0.5s ease;
            background: var(--light);
            border-radius: var(--border-radius);
            padding: 1.5rem;
            box-shadow: var(--shadow);
        }
        
        .thumbnail-container {
            position: relative;
            display: inline-block;
            margin-bottom: 1.5rem;
            border-radius: var(--border-radius-sm);
            overflow: hidden;
            box-shadow: var(--shadow);
        }
        
        .thumbnail {
            width: 100%;
            max-width: 400px;
            display: block;
            transition: var(--transition);
        }
        
        .thumbnail-container:hover .thumbnail {
            transform: scale(1.02);
        }
        
        .play-icon {
            position: absolute;
            top: 50%;
            left: 50%;
            transform: translate(-50%, -50%);
            color: white;
            font-size: 3rem;
            opacity: 0.8;
            text-shadow: 0 2px 10px rgba(0, 0, 0, 0.3);
            transition: var(--transition);
        }
        
        .thumbnail-container:hover .play-icon {
            opacity: 1;
            transform: translate(-50%, -50%) scale(1.1);
        }
        
        .video-title {
            font-weight: 600;
            font-size: 1.3rem;
            margin-bottom: 0.5rem;
            color: var(--dark);
            line-height: 1.4;
        }
        
        .video-author {
            color: var(--gray);
            margin-bottom: 1.5rem;
            font-size: 1rem;
            display: flex;
            align-items: center;
            justify-content: center;
        }
        
        .video-author i {
            margin-right: 8px;
            color: var(--primary);
        }
        
        .progress-container {
            width: 100%;
            background-color: var(--light-gray);
            border-radius: 50px;
            margin: 2rem 0;
            display: none;
            overflow: hidden;
            height: 8px;
            box-shadow: inset 0 1px 2px rgba(0, 0, 0, 0.1);
        }
        
        .progress-bar {
            height: 100%;
            background: var(--bg-gradient);
            width: 0%;
            transition: width 0.4s ease;
            position: relative;
            overflow: hidden;
        }
        
        .progress-bar::after {
            content: '';
            position: absolute;
            top: 0;
            left: 0;
            right: 0;
            bottom: 0;
            background: linear-gradient(
                90deg,
                rgba(255, 255, 255, 0) 0%,
                rgba(255, 255, 255, 0.3) 50%,
                rgba(255, 255, 255, 0) 100%
            );
            animation: shimmer 2s infinite;
        }
        
        .status {
            text-align: center;
            color: var(--gray);
            margin: 1.5rem 0;
            min-height: 24px;
            font-size: 1rem;
            font-weight: 500;
        }
        
        .error {
            color: var(--danger);
            text-align: center;
            margin: 1rem 0;
            padding: 1rem;
            background-color: rgba(234, 67, 53, 0.1);
            border-radius: var(--border-radius-sm);
            display: none;
            border-left: 4px solid var(--danger);
            font-weight: 500;
        }
        
        .error i {
            margin-right: 8px;
        }
        
        .download-options {
            display: none;
            margin-top: 2rem;
            animation: fadeIn 0.5s ease;
        }
        
        .download-options h3 {
            text-align: center;
            margin-bottom: 1.5rem;
            color: var(--dark);
            font-size: 1.4rem;
            font-weight: 600;
            position: relative;
            display: inline-block;
            width: 100%;
        }
        
        .download-options h3::after {
            content: '';
            display: block;
            width: 60px;
            height: 3px;
            background: var(--bg-gradient);
            margin: 0.5rem auto 0;
            border-radius: 3px;
        }
        
        .quality-options {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
            gap: 1.5rem;
            margin-bottom: 2rem;
        }
        
        .quality-option {
            background: white;
            border-radius: var(--border-radius-sm);
            padding: 1.8rem 1rem;
            text-align: center;
            box-shadow: var(--shadow);
            transition: var(--transition);
            border: 1px solid var(--light-gray);
            cursor: pointer;
            position: relative;
            overflow: hidden;
        }
        
        .quality-option::before {
            content: '';
            position: absolute;
            top: 0;
            left: 0;
            width: 100%;
            height: 4px;
            background: var(--bg-gradient);
            transition: var(--transition);
            transform: scaleX(0);
            transform-origin: left;
        }
        
        .quality-option:hover {
            transform: translateY(-5px);
            box-shadow: var(--shadow-hover);
        }
        
        .quality-option:hover::before {
            transform: scaleX(1);
        }
        
        .quality-option.selected {
            border-color: var(--primary);
            background-color: var(--primary-light);
        }
        
        .quality-option.selected::before {
            transform: scaleX(1);
        }
        
        .quality-option i {
            font-size: 2.5rem;
            color: var(--primary);
            margin-bottom: 1rem;
            transition: var(--transition);
        }
        
        .quality-option:hover i {
            transform: scale(1.1);
        }
        
        .quality-option h4 {
            font-size: 1.2rem;
            margin-bottom: 0.5rem;
            color: var(--dark);
            font-weight: 600;
        }
        
        .quality-option p {
            color: var(--gray);
            font-size: 0.95rem;
            margin-bottom: 0.5rem;
        }
        
        .quality-option .file-size {
            font-weight: 500;
            color: var(--dark-gray);
        }
        
        .download-btn {
            display: block;
            width: 100%;
            background: var(--bg-gradient);
            color: white;
            border: none;
            padding: 1.2rem;
            border-radius: 50px;
            font-size: 1.1rem;
            font-weight: 600;
            text-align: center;
            text-decoration: none;
            margin-top: 1.5rem;
            cursor: pointer;
            transition: var(--transition);
            box-shadow: 0 4px 15px rgba(255, 0, 0, 0.3);
            position: relative;
            overflow: hidden;
        }
        
        .download-btn::after {
            content: '';
            position: absolute;
            top: 0;
            left: 0;
            width: 100%;
            height: 100%;
            background: linear-gradient(
                90deg,
                rgba(255, 255, 255, 0) 0%,
                rgba(255, 255, 255, 0.2) 50%,
                rgba(255, 255, 255, 0) 100%
            );
            transform: translateX(-100%);
        }
        
        .download-btn:hover {
            transform: translateY(-3px);
            box-shadow: 0 8px 25px rgba(255, 0, 0, 0.4);
        }
        
        .download-btn:hover::after {
            animation: shimmer 1.5s infinite;
        }
        
        .download-btn:active {
            transform: translateY(0);
        }
        
        .download-btn i {
            margin-right: 10px;
        }
        
        /* Features Section */
        .features {
            padding: 4rem 2rem;
            background: white;
            width: 100%;
            max-width: 1200px;
            margin: 0 auto;
            border-radius: var(--border-radius);
            box-shadow: var(--shadow);
            margin-bottom: 2rem;
        }
        
        .section-title {
            text-align: center;
            margin-bottom: 3rem;
            color: var(--dark);
            position: relative;
        }
        
        .section-title h2 {
            font-size: 2.2rem;
            font-weight: 700;
            margin-bottom: 1rem;
        }
        
        .section-title p {
            color: var(--gray);
            max-width: 700px;
            margin: 0 auto;
            font-size: 1.1rem;
        }
        
        .section-title::after {
            content: '';
            display: block;
            width: 80px;
            height: 4px;
            background: var(--bg-gradient);
            margin: 1.5rem auto 0;
            border-radius: 4px;
        }
        
        .features-grid {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
            gap: 2rem;
        }
        
        .feature-card {
            background: var(--light);
            border-radius: var(--border-radius-sm);
            padding: 2rem;
            text-align: center;
            transition: var(--transition);
            border: 1px solid var(--light-gray);
        }
        
        .feature-card:hover {
            transform: translateY(-5px);
            box-shadow: var(--shadow-hover);
            border-color: var(--primary);
        }
        
        .feature-icon {
            font-size: 2.5rem;
            color: var(--primary);
            margin-bottom: 1.5rem;
            transition: var(--transition);
        }
        
        .feature-card:hover .feature-icon {
            transform: scale(1.1);
        }
        
        .feature-card h3 {
            font-size: 1.3rem;
            margin-bottom: 1rem;
            color: var(--dark);
        }
        
        .feature-card p {
            color: var(--gray);
            font-size: 0.95rem;
        }
        
        /* How It Works Section */
        .how-it-works {
            padding: 4rem 2rem;
            background: var(--light);
            width: 100%;
            max-width: 1200px;
            margin: 0 auto;
            border-radius: var(--border-radius);
            box-shadow: var(--shadow);
            margin-bottom: 2rem;
        }
        
        .steps {
            display: flex;
            flex-direction: column;
            gap: 2rem;
            max-width: 800px;
            margin: 0 auto;
            position: relative;
        }
        
        .steps::before {
            content: '';
            position: absolute;
            top: 0;
            left: 30px;
            height: 100%;
            width: 3px;
            background: var(--bg-gradient);
            z-index: 1;
        }
        
        .step {
            display: flex;
            gap: 1.5rem;
            position: relative;
            z-index: 2;
        }
        
        .step-number {
            min-width: 60px;
            height: 60px;
            background: var(--bg-gradient);
            color: white;
            border-radius: 50%;
            display: flex;
            align-items: center;
            justify-content: center;
            font-size: 1.5rem;
            font-weight: 700;
            box-shadow: 0 4px 10px rgba(255, 0, 0, 0.2);
            flex-shrink: 0;
        }
        
        .step-content {
            background: white;
            padding: 1.5rem;
            border-radius: var(--border-radius-sm);
            box-shadow: var(--shadow);
            flex: 1;
        }
        
        .step-content h3 {
            font-size: 1.2rem;
            margin-bottom: 0.5rem;
            color: var(--dark);
        }
        
        .step-content p {
            color: var(--gray);
            font-size: 0.95rem;
        }
        
        /* FAQ Section */
        .faq {
            padding: 4rem 2rem;
            background: white;
            width: 100%;
            max-width: 1200px;
            margin: 0 auto;
            border-radius: var(--border-radius);
            box-shadow: var(--shadow);
            margin-bottom: 2rem;
        }
        
        .faq-container {
            max-width: 800px;
            margin: 0 auto;
        }
        
        .faq-item {
            margin-bottom: 1rem;
            border: 1px solid var(--light-gray);
            border-radius: var(--border-radius-sm);
            overflow: hidden;
            transition: var(--transition);
        }
        
        .faq-item:hover {
            border-color: var(--primary);
        }
        
        .faq-question {
            padding: 1.5rem;
            background: var(--light);
            cursor: pointer;
            display: flex;
            justify-content: space-between;
            align-items: center;
            font-weight: 600;
            transition: var(--transition);
        }
        
        .faq-question:hover {
            background: rgba(255, 0, 0, 0.05);
        }
        
        .faq-question i {
            color: var(--primary);
            transition: var(--transition);
        }
        
        .faq-item.active .faq-question i {
            transform: rotate(180deg);
        }
        
        .faq-answer {
            padding: 0 1.5rem;
            max-height: 0;
            overflow: hidden;
            transition: max-height 0.3s ease;
        }
        
        .faq-item.active .faq-answer {
            padding: 1.5rem;
            max-height: 500px;
        }
        
        .faq-answer p {
            color: var(--gray);
            line-height: 1.7;
        }
        
        /* Footer Styles */
        footer {
            background: var(--dark);
            color: white;
            padding: 4rem 2rem 2rem;
            text-align: center;
        }
        
        .footer-content {
            max-width: 1200px;
            margin: 0 auto;
        }
        
        .footer-grid {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
            gap: 2rem;
            text-align: left;
            margin-bottom: 3rem;
        }
        
        .footer-column h3 {
            font-size: 1.2rem;
            margin-bottom: 1.5rem;
            color: white;
            position: relative;
            display: inline-block;
        }
        
        .footer-column h3::after {
            content: '';
            position: absolute;
            bottom: -8px;
            left: 0;
            width: 40px;
            height: 3px;
            background: var(--primary);
        }
        
        .footer-column ul {
            list-style: none;
        }
        
        .footer-column li {
            margin-bottom: 0.8rem;
        }
        
        .footer-column a {
            color: rgba(255, 255, 255, 0.7);
            text-decoration: none;
            transition: var(--transition);
            display: inline-block;
        }
        
        .footer-column a:hover {
            color: white;
            transform: translateX(5px);
        }
        
        .footer-column a i {
            margin-right: 8px;
            width: 20px;
            text-align: center;
        }
        
        .footer-logo {
            font-size: 2rem;
            font-weight: 700;
            margin-bottom: 1.5rem;
            display: inline-block;
        }
        
        .footer-logo span {
            color: var(--primary);
        }
        
        .footer-description {
            max-width: 600px;
            margin: 0 auto 2rem;
            color: rgba(255, 255, 255, 0.7);
            line-height: 1.6;
            font-size: 0.95rem;
        }
        
        .social-icons {
            display: flex;
            justify-content: center;
            margin-bottom: 2rem;
            gap: 1rem;
        }
        
        .social-icons a {
            color: white;
            background: rgba(255, 255, 255, 0.1);
            width: 45px;
            height: 45px;
            border-radius: 50%;
            display: flex;
            align-items: center;
            justify-content: center;
            transition: var(--transition);
            font-size: 1.1rem;
        }
        
        .social-icons a:hover {
            background: var(--primary);
            transform: translateY(-3px);
        }
        
        .footer-bottom {
            border-top: 1px solid rgba(255, 255, 255, 0.1);
            padding-top: 2rem;
            color: rgba(255, 255, 255, 0.5);
            font-size: 0.9rem;
        }
        
        /* Animations */
        @keyframes fadeIn {
            from { opacity: 0; transform: translateY(20px); }
            to { opacity: 1; transform: translateY(0); }
        }
        
        @keyframes shimmer {
            0% { transform: translateX(-100%); }
            100% { transform: translateX(100%); }
        }
        
        /* Responsive Design */
        @media (max-width: 992px) {
            .hero h1 {
                font-size: 2.2rem;
            }
            
            .quality-options {
                grid-template-columns: repeat(2, 1fr);
            }
        }
        
        @media (max-width: 768px) {
            .header-container {
                padding: 0 1.5rem;
            }
            
            .nav-toggle {
                display: block;
            }
            
            .nav-menu {
                position: fixed;
                top: 70px;
                left: -100%;
                width: 100%;
                height: calc(100vh - 70px);
                background: var(--dark);
                flex-direction: column;
                align-items: center;
                padding: 2rem 0;
                transition: var(--transition);
            }
            
            .nav-menu.active {
                left: 0;
            }
            
            .nav-menu li {
                margin: 0.8rem 0;
            }
            
            .nav-menu a {
                padding: 0.8rem 1.5rem;
            }
            
            .hero {
                padding: 2.5rem 1.5rem;
            }
            
            .hero h1 {
                font-size: 2rem;
            }
            
            .hero p {
                font-size: 1rem;
            }
            
            .input-group {
                flex-direction: column;
                border-radius: var(--border-radius-sm);
            }
            
            #youtube-url {
                border-radius: var(--border-radius-sm) var(--border-radius-sm) 0 0;
                padding: 1.2rem 1.5rem;
            }
            
            #convert-btn {
                border-radius: 0 0 var(--border-radius-sm) var(--border-radius-sm);
                padding: 1.2rem;
                width: 100%;
            }
            
            .quality-options {
                grid-template-columns: 1fr;
            }
            
            .section-title h2 {
                font-size: 1.8rem;
            }
            
            .features, .how-it-works, .faq {
                padding: 3rem 1.5rem;
            }
            
            .step {
                flex-direction: column;
                gap: 1rem;
            }
            
            .steps::before {
                left: 30px;
            }
        }
        
        @media (max-width: 576px) {
            .header-container {
                padding: 0 1rem;
            }
            
            .logo {
                font-size: 1.5rem;
            }
            
            .logo i {
                font-size: 1.7rem;
            }
            
            .hero {
                padding: 2rem 1rem;
            }
            
            .hero h1 {
                font-size: 1.7rem;
            }
            
            .converter-section {
                padding: 2rem 1.5rem;
            }
            
            .features, .how-it-works, .faq {
                padding: 2.5rem 1rem;
            }
            
            .section-title h2 {
                font-size: 1.6rem;
            }
            
            .footer-grid {
                grid-template-columns: 1fr;
                text-align: center;
            }
            
            .footer-column h3::after {
                left: 50%;
                transform: translateX(-50%);
            }
        }