:root {
            --primary: #4361ee;
            --secondary: #3f37c9;
            --accent: #4895ef;
            --light: #f8f9fa;
            --dark: #212529;
            --success: #4cc9f0;
            --warning: #f72585;
            --font-base: 1rem;
            --font-scale: 1.2;
            --border-radius: 8px;
            --box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
            --transition: all 0.3s ease;
        }
        
        * {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
            font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
        }
        
        body {
            background-color: #f5f7ff;
            color: var(--dark);
            line-height: 1.6;
            min-height: 100vh;
            overflow-x: hidden;
            font-size: var(--font-base);
        }
        
        .container {
            width: 100%;
            max-width: 1200px;
            margin: 0 auto;
            padding: 0 1rem;
        }
        
        header {
            background: linear-gradient(135deg, var(--primary), var(--secondary));
            color: white;
            padding: 1rem 0;
            text-align: center;
            border-radius: 0 0 1.25rem 1.25rem;
            box-shadow: 0 0.625rem 1.875rem rgba(67, 97, 238, 0.2);
        }
        
        .logo {
            font-size: clamp(1.5rem, 4vw, 2rem);
            font-weight: 800;
            margin-bottom: 0.25rem;
            letter-spacing: -0.5px;
        }
        
        .slogan {
            font-size: clamp(0.875rem, 2.5vw, 1rem);
            opacity: 0.9;
            margin-bottom: 0.5rem;
            padding: 0 1rem;
        }
        
        .hero {
            text-align: center;
            padding: 1.5rem 0;
        }
        
        .hero h1 {
            font-size: clamp(1.5rem, 4vw, 2rem);
            margin-bottom: 0.75rem;
            color: var(--dark);
            line-height: 1.3;
        }
        
        .hero p {
            font-size: clamp(0.875rem, 2.5vw, 1rem);
            max-width: 700px;
            margin: 0 auto 1.5rem;
            color: #666;
            padding: 0 1rem;
        }
        
        .converter-container {
            display: grid;
            grid-template-columns: 1fr;
            gap: 1.5rem;
        }
        
        @media (min-width: 768px) {
            .converter-container {
                grid-template-columns: 1fr 1fr;
            }
        }
        
        .converter-box {
            background-color: white;
            border-radius: var(--border-radius);
            padding: 1rem;
            box-shadow: var(--box-shadow);
            transition: var(--transition);
            overflow-y: auto;
            display: flex;
            flex-direction: column;
            will-change: transform;
        }
        
        .converter-box:hover {
            transform: translateY(-3px);
            box-shadow: 0 6px 12px rgba(0, 0, 0, 0.1);
        }
        
        .converter-box h2 {
            color: var(--primary);
            margin-bottom: 1rem;
            font-size: clamp(1.1rem, 3vw, 1.3rem);
            display: flex;
            align-items: center;
            gap: 0.5rem;
        }
        
        /* Tab styles */
        .input-method-tabs {
            display: flex;
            margin-bottom: 1rem;
            border-bottom: 1px solid #ddd;
        }
        
        .tab-btn {
            flex: 1;
            padding: 0.5rem;
            border: none;
            background: none;
            cursor: pointer;
            transition: var(--transition);
            position: relative;
            font-weight: 500;
            color: #666;
        }
        
        .tab-btn::after {
            content: '';
            position: absolute;
            bottom: -1px;
            left: 0;
            width: 100%;
            height: 2px;
            background-color: var(--primary);
            transform: scaleX(0);
            transition: transform 0.3s ease;
        }
        
        .tab-btn.active {
            color: var(--primary);
        }
        
        .tab-btn.active::after {
            transform: scaleX(1);
        }
        
        .tab-content {
            display: none;
            animation: fadeIn 0.3s ease;
        }
        
        .tab-content.active {
            display: block;
        }
        
        @keyframes fadeIn {
            from { opacity: 0; }
            to { opacity: 1; }
        }
        
        /* Drop area styles */
        .drop-area {
            border: 2px dashed #ccc;
            border-radius: var(--border-radius);
            padding: 1.5rem;
            text-align: center;
            cursor: pointer;
            transition: var(--transition);
            margin-bottom: 1rem;
            will-change: border-color, background-color;
        }
        
        .drop-area.highlight {
            border-color: var(--accent);
            background-color: rgba(72, 149, 239, 0.05);
        }
        
        .drop-content {
            display: flex;
            flex-direction: column;
            align-items: center;
            gap: 0.8rem;
        }
        
        .drop-content i {
            font-size: clamp(2rem, 6vw, 3rem);
            color: var(--accent);
        }
        
        .drop-content p {
            font-size: clamp(0.9rem, 2vw, 1rem);
        }
        
        .file-input {
            display: none;
        }
        
        .btn {
            background-color: var(--primary);
            color: white;
            border: none;
            padding: 0.6rem 1.2rem;
            border-radius: var(--border-radius);
            cursor: pointer;
            font-size: clamp(0.8rem, 2vw, 1rem);
            font-weight: 500;
            transition: var(--transition);
            display: inline-flex;
            align-items: center;
            gap: 0.4rem;
            will-change: transform, background-color;
            transform: translateZ(0);
        }
        
        .btn:hover {
            background-color: var(--secondary);
        }
        
        .btn:disabled {
            background-color: #ccc;
            cursor: not-allowed;
        }
        
        .browse-btn {
            background-color: var(--accent);
        }
        
        .copy-btn, .download-btn {
            padding: 0.5rem 0.8rem;
            font-size: 0.8rem;
        }
        
        .remove-btn {
            background-color: var(--warning);
            padding: 0.4rem;
            border-radius: 50%;
            width: 28px;
            height: 28px;
            display: flex;
            align-items: center;
            justify-content: center;
        }
        
        .file-info {
            display: flex;
            align-items: center;
            gap: 0.8rem;
            padding: 0.8rem;
            background-color: #f8f9fa;
            border-radius: var(--border-radius);
            margin-bottom: 0.8rem;
        }
        
        .file-icon {
            width: 40px;
            height: 40px;
            background-color: var(--accent);
            border-radius: var(--border-radius);
            display: flex;
            align-items: center;
            justify-content: center;
            color: white;
            font-size: 1.2rem;
        }
        
        .file-details {
            flex: 1;
            display: flex;
            flex-direction: column;
            overflow: hidden;
        }
        
        .file-name {
            font-weight: 500;
            font-size: 0.9rem;
            white-space: nowrap;
            overflow: hidden;
            text-overflow: ellipsis;
        }
        
        .file-size {
            font-size: 0.8rem;
            color: #666;
        }
        
        .preview-content, .file-preview {
            width: 100%;
            max-height: 250px;
            overflow: auto;
            border: 1px solid #eee;
            border-radius: var(--border-radius);
            padding: 0.8rem;
            background-color: #f8f9fa;
            will-change: contents;
        }
        
        .preview-content img, .preview-content video, 
        .file-preview img, .file-preview video {
            max-width: 100%;
            max-height: 200px;
            display: block;
            margin: 0 auto;
        }
        
        .result-area textarea, .input-area textarea {
            width: 100%;
            min-height: 150px;
            padding: 0.8rem;
            border: 1px solid #ddd;
            border-radius: var(--border-radius);
            font-family: monospace;
            resize: vertical;
            margin-bottom: 0.8rem;
            font-size: 0.85rem;
            will-change: contents;
            backface-visibility: hidden;
        }
        
        .result-header {
            display: flex;
            justify-content: space-between;
            align-items: center;
            margin-bottom: 0.8rem;
        }
        
        .result-header h3 {
            font-size: 1rem;
        }
        
        .action-buttons {
            display: flex;
            gap: 0.4rem;
        }
        
        .file-type-selector {
            margin-bottom: 0.8rem;
            display: flex;
            align-items: center;
            gap: 0.4rem;
            flex-wrap: wrap;
        }
        
        .file-type-selector label {
            font-size: 0.9rem;
        }
        
        .file-type-selector select {
            padding: 0.4rem;
            border-radius: var(--border-radius);
            border: 1px solid #ddd;
            font-size: 0.9rem;
        }
        
        .loading-indicator {
            position: fixed;
            top: 0;
            left: 0;
            width: 100%;
            height: 100%;
            background: rgba(0,0,0,0.5);
            display: flex;
            flex-direction: column;
            align-items: center;
            justify-content: center;
            z-index: 1000;
            color: white;
        }
        
        .loading-indicator .spinner {
            border: 5px solid #f3f3f3;
            border-top: 5px solid #3498db;
            border-radius: 50%;
            width: 50px;
            height: 50px;
            animation: spin 1s linear infinite;
            margin-bottom: 15px;
        }
        

             /* Footer */
        footer {
            background: var(--dark);
            color: white;
            padding: 1.5rem 0;
            text-align: center;
            margin-top: 1.5rem;
        }
        
        .footer-logo {
            font-size: clamp(1.25rem, 3vw, 1.5rem);
            font-weight: 700;
            margin-bottom: 0.75rem;
        }
        
        .copyright {
            opacity: 0.7;
            font-size: clamp(0.75rem, 2vw, 0.8125rem);
        }


        @keyframes spin {
            0% { transform: rotate(0deg); }
            100% { transform: rotate(360deg); }
        }
        
        .hidden {
            display: none;
        }
        
        /* Accessibility improvements */
        a:focus, button:focus {
            outline: 2px solid var(--accent);
            outline-offset: 2px;
        }
        
        /* Reduced motion preference */
        @media (prefers-reduced-motion: reduce) {
            * {
                animation-duration: 0.01ms !important;
                animation-iteration-count: 1 !important;
                transition-duration: 0.01ms !important;
                scroll-behavior: auto !important;
            }
        }
        
        /* Responsive adjustments */
        @media (max-width: 768px) {
            .container {
                padding: 0 0.75rem;
            }
            
            header {
                padding: 0.75rem 0;
                border-radius: 0 0 1rem 1rem;
            }
            
            .hero {
                padding: 1rem 0;
            }
        }
        
        @media (max-width: 480px) {
            .container {
                padding: 0 0.5rem;
            }
            
            .btn {
                padding: 0.5rem 0.8rem;
            }
            
            footer {
                padding: 1rem 0;
            }
            
            .drop-area {
                padding: 1rem;
            }
            
            .file-info {
                padding: 0.6rem;
            }
            
            .result-header {
                flex-direction: column;
                align-items: flex-start;
                gap: 0.5rem;
            }
            
            .action-buttons {
                width: 100%;
            }
            
            .action-buttons .btn {
                flex: 1;
                justify-content: center;
            }
        }