:root {
            --primary: #0ea5e9;
            --primary-dark: #0284c7;
            --secondary: #8b5cf6;
            --secondary-dark: #7c3aed;
            --danger: #ef4444;
            --danger-dark: #dc2626;
            --success: #10b981;
            --success-dark: #059669;
            --warning: #f59e0b;
            --warning-dark: #d97706;
            --dark: #1e293b;
            --light: #f8fafc;
            --gray: #64748b;
            --gray-light: #e2e8f0;
            --premium-gold: #f59e0b;
            --shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -2px rgba(0, 0, 0, 0.05);
            --radius: 12px;
            --transition: all 0.3s ease;
        }

        * {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
            font-family: 'Segoe UI', system-ui, -apple-system, sans-serif;
        }

        body {
            background: linear-gradient(135deg, #f0f9ff 0%, #f5f3ff 100%);
            color: var(--dark);
            line-height: 1.6;
            min-height: 100vh;
        }

        .container {
            max-width: 1400px;
            margin: 0 auto;
            padding: 20px;
        }

        /* Header & Premium Badge */
        header {
            text-align: center;
            margin-bottom: 40px;
            position: relative;
        }

        .logo {
            display: flex;
            align-items: center;
            justify-content: center;
            gap: 15px;
            margin-bottom: 10px;
        }

        .logo i {
            font-size: 2.8rem;
            background: linear-gradient(to right, var(--primary), var(--secondary));
            -webkit-background-clip: text;
            background-clip: text;
            color: transparent;
        }

        .logo-text {
            font-size: 2.5rem;
            font-weight: 800;
            background: linear-gradient(to right, var(--primary), var(--secondary));
            -webkit-background-clip: text;
            background-clip: text;
            color: transparent;
        }

        .premium-badge {
            display: inline-flex;
            align-items: center;
            gap: 8px;
            background: linear-gradient(135deg, #fbbf24, #f59e0b);
            color: #78350f;
            padding: 8px 20px;
            border-radius: 50px;
            font-weight: 700;
            font-size: 0.9rem;
            margin-top: 10px;
            box-shadow: 0 4px 10px rgba(245, 158, 11, 0.3);
        }

        .tagline {
            color: var(--gray);
            font-size: 1.1rem;
            margin-top: 10px;
            max-width: 700px;
            margin-left: auto;
            margin-right: auto;
        }

        /* Main Layout */
        .main-content {
            display: grid;
            grid-template-columns: 1fr 1fr;
            gap: 30px;
            margin-bottom: 40px;
        }

        @media (max-width: 992px) {
            .main-content {
                grid-template-columns: 1fr;
            }
        }

        /* Cards */
        .upload-card, .preview-card, .settings-card, .batch-card {
            background: white;
            border-radius: var(--radius);
            padding: 30px;
            box-shadow: var(--shadow);
            height: fit-content;
        }

        .upload-card {
            border-top: 5px solid var(--primary);
        }

        .preview-card {
            border-top: 5px solid var(--secondary);
        }

        .settings-card {
            border-top: 5px solid var(--success);
        }

        .batch-card {
            border-top: 5px solid var(--warning);
        }

        .card-header {
            display: flex;
            align-items: center;
            gap: 12px;
            margin-bottom: 25px;
            padding-bottom: 15px;
            border-bottom: 2px solid var(--gray-light);
        }

        .card-header i {
            font-size: 1.8rem;
            color: var(--primary);
        }

        .card-title {
            font-size: 1.5rem;
            font-weight: 700;
        }

        /* Upload Area */
        .upload-area {
            border: 3px dashed var(--gray-light);
            border-radius: var(--radius);
            padding: 50px 30px;
            text-align: center;
            transition: var(--transition);
            margin-bottom: 25px;
            position: relative;
            background: var(--light);
        }

        .upload-area.dragover {
            border-color: var(--primary);
            background: rgba(14, 165, 233, 0.05);
        }

        .upload-icon {
            font-size: 4rem;
            color: var(--primary);
            margin-bottom: 20px;
        }

        .upload-text {
            font-size: 1.2rem;
            margin-bottom: 10px;
            font-weight: 600;
        }

        .upload-subtext {
            color: var(--gray);
            margin-bottom: 20px;
        }

        .file-input {
            display: none;
        }

        .upload-btn, .convert-btn {
            background: linear-gradient(to right, var(--primary), var(--primary-dark));
            color: white;
            border: none;
            border-radius: var(--radius);
            padding: 14px 30px;
            font-size: 1rem;
            font-weight: 600;
            cursor: pointer;
            transition: var(--transition);
            display: inline-flex;
            align-items: center;
            gap: 10px;
        }

        .upload-btn:hover, .convert-btn:hover {
            transform: translateY(-2px);
            box-shadow: 0 5px 15px rgba(14, 165, 233, 0.2);
        }

        .convert-btn {
            background: linear-gradient(to right, var(--success), var(--success-dark));
            width: 100%;
            justify-content: center;
            padding: 18px;
            font-size: 1.1rem;
            margin-top: 20px;
        }

        .convert-btn:hover {
            box-shadow: 0 5px 15px rgba(16, 185, 129, 0.2);
        }

        /* File List */
        .file-list {
            margin-top: 20px;
        }

        .file-item {
            display: flex;
            align-items: center;
            gap: 15px;
            padding: 15px;
            background: var(--light);
            border-radius: var(--radius);
            margin-bottom: 10px;
            border: 1px solid var(--gray-light);
        }

        .file-icon {
            color: var(--primary);
            font-size: 1.5rem;
        }

        .file-info {
            flex: 1;
        }

        .file-name {
            font-weight: 600;
            margin-bottom: 5px;
            word-break: break-all;
        }

        .file-size {
            color: var(--gray);
            font-size: 0.9rem;
        }

        .file-actions {
            display: flex;
            gap: 10px;
        }

        .file-action-btn {
            background: none;
            border: none;
            color: var(--gray);
            cursor: pointer;
            font-size: 1.2rem;
            transition: var(--transition);
            padding: 5px;
        }

        .file-action-btn:hover {
            color: var(--danger);
        }

        .file-action-btn.preview:hover {
            color: var(--primary);
        }

        /* Settings */
        .settings-group {
            margin-bottom: 25px;
        }

        .setting-label {
            display: flex;
            align-items: center;
            gap: 8px;
            margin-bottom: 10px;
            font-weight: 600;
            color: var(--dark);
        }

        .setting-label i {
            color: var(--primary);
        }

        .checkbox-group {
            display: flex;
            flex-wrap: wrap;
            gap: 15px;
            margin-top: 10px;
        }

        .checkbox-item {
            display: flex;
            align-items: center;
            gap: 8px;
        }

        .checkbox-item input[type="checkbox"] {
            width: 18px;
            height: 18px;
            accent-color: var(--primary);
        }

        .select-wrapper {
            position: relative;
        }

        .select-wrapper select {
            width: 100%;
            padding: 12px 15px;
            border: 2px solid var(--gray-light);
            border-radius: var(--radius);
            font-size: 1rem;
            appearance: none;
            background: white;
            cursor: pointer;
        }

        .select-wrapper:after {
            content: '\f078';
            font-family: 'Font Awesome 6 Free';
            font-weight: 900;
            position: absolute;
            right: 15px;
            top: 50%;
            transform: translateY(-50%);
            color: var(--gray);
            pointer-events: none;
        }

        /* Preview Area */
        .preview-container {
            background: #f5f5f5;
            border-radius: var(--radius);
            padding: 20px;
            min-height: 300px;
            max-height: 500px;
            overflow-y: auto;
            margin-bottom: 20px;
            border: 1px solid var(--gray-light);
        }

        .preview-content {
            background: white;
            padding: 30px;
            border-radius: 8px;
            box-shadow: 0 2px 10px rgba(0, 0, 0, 0.05);
            min-height: 200px;
        }

        .preview-placeholder {
            display: flex;
            flex-direction: column;
            align-items: center;
            justify-content: center;
            height: 200px;
            color: var(--gray);
        }

        .preview-placeholder i {
            font-size: 3rem;
            margin-bottom: 15px;
        }

        .pdf-preview {
            width: 100%;
            height: auto;
            border-radius: 4px;
        }

        .preview-actions {
            display: flex;
            gap: 15px;
            margin-top: 20px;
        }

        .preview-btn {
            flex: 1;
            padding: 14px;
            border: none;
            border-radius: var(--radius);
            font-weight: 600;
            cursor: pointer;
            transition: var(--transition);
            display: flex;
            align-items: center;
            justify-content: center;
            gap: 10px;
        }

        .preview-btn.download {
            background: linear-gradient(to right, var(--success), var(--success-dark));
            color: white;
        }

        .preview-btn.download:hover {
            box-shadow: 0 5px 15px rgba(16, 185, 129, 0.2);
        }

        .preview-btn.share {
            background: var(--light);
            color: var(--dark);
            border: 2px solid var(--gray-light);
        }

        .preview-btn.share:hover {
            border-color: var(--primary);
            color: var(--primary);
        }

        /* Batch Processing */
        .batch-upload-area {
            border: 2px dashed var(--gray-light);
            border-radius: var(--radius);
            padding: 30px;
            text-align: center;
            margin-bottom: 20px;
            background: var(--light);
            transition: var(--transition);
        }

        .batch-upload-area.dragover {
            border-color: var(--warning);
            background: rgba(245, 158, 11, 0.05);
        }

        .batch-btn {
            background: linear-gradient(to right, var(--warning), var(--warning-dark));
            color: white;
            border: none;
            border-radius: var(--radius);
            padding: 14px 25px;
            font-size: 1rem;
            font-weight: 600;
            cursor: pointer;
            transition: var(--transition);
            display: inline-flex;
            align-items: center;
            gap: 10px;
            margin-top: 15px;
        }

        .batch-btn:hover {
            transform: translateY(-2px);
            box-shadow: 0 5px 15px rgba(245, 158, 11, 0.2);
        }

        .batch-stats {
            display: grid;
            grid-template-columns: repeat(2, 1fr);
            gap: 15px;
            margin-top: 20px;
        }

        .stat-item {
            background: var(--light);
            padding: 15px;
            border-radius: var(--radius);
            text-align: center;
        }

        .stat-value {
            font-size: 1.8rem;
            font-weight: 800;
            color: var(--primary);
            margin-bottom: 5px;
        }

        .stat-label {
            font-size: 0.9rem;
            color: var(--gray);
        }

        /* AI Features */
        .ai-features {
            display: grid;
            grid-template-columns: repeat(2, 1fr);
            gap: 15px;
            margin-top: 25px;
        }

        @media (max-width: 768px) {
            .ai-features {
                grid-template-columns: 1fr;
            }
        }

        .ai-feature {
            background: rgba(139, 92, 246, 0.05);
            border: 1px solid rgba(139, 92, 246, 0.2);
            border-radius: var(--radius);
            padding: 20px;
            display: flex;
            align-items: center;
            gap: 15px;
        }

        .ai-feature i {
            font-size: 1.8rem;
            color: var(--secondary);
        }

        .ai-feature-text h4 {
            font-size: 1rem;
            margin-bottom: 5px;
        }

        .ai-feature-text p {
            font-size: 0.9rem;
            color: var(--gray);
        }

        /* Toast Notification */
        .toast {
            position: fixed;
            bottom: 30px;
            right: 30px;
            background: var(--dark);
            color: white;
            padding: 15px 25px;
            border-radius: var(--radius);
            box-shadow: var(--shadow);
            display: flex;
            align-items: center;
            gap: 10px;
            z-index: 1000;
            transform: translateY(100px);
            opacity: 0;
            transition: var(--transition);
        }

        .toast.show {
            transform: translateY(0);
            opacity: 1;
        }

        .toast.success {
            background: var(--success);
        }

        .toast.warning {
            background: var(--warning);
        }

        .toast.error {
            background: var(--danger);
        }

        .toast i {
            font-size: 1.2rem;
        }

        /* Progress Bar */
        .progress-container {
            width: 100%;
            background: var(--gray-light);
            border-radius: 50px;
            margin: 20px 0;
            overflow: hidden;
            display: none;
        }

        .progress-bar {
            height: 10px;
            background: linear-gradient(to right, var(--primary), var(--secondary));
            border-radius: 50px;
            width: 0%;
            transition: width 0.3s ease;
        }

        /* Footer */
        footer {
            text-align: center;
            padding: 30px 0;
            color: var(--gray);
            font-size: 0.9rem;
            border-top: 1px solid var(--gray-light);
            margin-top: 40px;
        }

        .footer-links {
            display: flex;
            justify-content: center;
            flex-wrap: wrap;
            gap: 25px;
            margin-top: 15px;
        }

        .footer-links a {
            color: var(--primary);
            text-decoration: none;
            font-weight: 600;
            display: flex;
            align-items: center;
            gap: 8px;
        }

        .footer-links a:hover {
            text-decoration: underline;
        }

        /* Responsive Adjustments */
        @media (max-width: 768px) {
            .container {
                padding: 15px;
            }
            
            .logo-text {
                font-size: 2rem;
            }
            
            .upload-card, .preview-card, .settings-card, .batch-card {
                padding: 20px;
            }
            
            .preview-actions {
                flex-direction: column;
            }
            
            .batch-stats {
                grid-template-columns: 1fr;
            }
            
            .footer-links {
                flex-direction: column;
                gap: 10px;
            }
        }

        @media (max-width: 480px) {
            .logo {
                flex-direction: column;
                gap: 5px;
            }
            
            .main-content {
                gap: 20px;
            }
            
            .card-header {
                flex-direction: column;
                text-align: center;
                gap: 8px;
            }
            
            .file-item {
                flex-direction: column;
                text-align: center;
            }
            
            .file-actions {
                justify-content: center;
            }
        }