:root {
            --primary-gradient: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
            --secondary-gradient: linear-gradient(135deg, #f093fb 0%, #f5576c 100%);
            --success-gradient: linear-gradient(135deg, #4facfe 0%, #00f2fe 100%);
            --danger-gradient: linear-gradient(135deg, #fa709a 0%, #fee140 100%);
            --glass-bg: rgba(255, 255, 255, 0.1);
            --glass-border: rgba(255, 255, 255, 0.2);
            --text-primary: #2d3748;
            --text-secondary: #718096;
            --border-color: #e2e8f0;
            --shadow-light: 0 4px 20px rgba(0, 0, 0, 0.1);
            --shadow-medium: 0 8px 32px rgba(0, 0, 0, 0.15);
            --shadow-heavy: 0 20px 60px rgba(0, 0, 0, 0.2);
        }

        * {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
        }

        body {
            font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
            background: var(--primary-gradient);
            min-height: 100vh;
            overflow-x: hidden;
            position: relative;
        }

        .background-particles {
            position: fixed;
            top: 0;
            left: 0;
            width: 100%;
            height: 100%;
            z-index: -1;
            overflow: hidden;
        }

        .particle {
            position: absolute;
            width: 4px;
            height: 4px;
            background: rgba(255, 255, 255, 0.6);
            border-radius: 50%;
            animation: float 15s infinite ease-in-out;
        }

        @keyframes float {
            0%, 100% { transform: translateY(100vh) rotate(0deg); opacity: 0; }
            10% { opacity: 1; }
            90% { opacity: 1; }
        }

        .container {
            max-width: 1400px;
            margin: 0 auto;
            padding: 2rem;
            position: relative;
            z-index: 1;
        }

        .header {
            text-align: center;
            margin-bottom: 3rem;
            animation: slideDown 0.8s cubic-bezier(0.25, 0.46, 0.45, 0.94);
        }

        @keyframes slideDown {
            from { opacity: 0; transform: translateY(-50px) scale(0.95); }
            to { opacity: 1; transform: translateY(0) scale(1); }
        }

        .logo {
            font-size: 3.5rem;
            font-weight: 900;
            background: linear-gradient(45deg, #fff, #f0f0f0, #fff);
            -webkit-background-clip: text;
            -webkit-text-fill-color: transparent;
            background-clip: text;
            margin-bottom: 0.5rem;
            text-shadow: 0 0 40px rgba(255,255,255,0.6);
            animation: glow 2s ease-in-out infinite alternate;
        }

        @keyframes glow {
            from { filter: drop-shadow(0 0 20px rgba(255,255,255,0.3)); }
            to { filter: drop-shadow(0 0 40px rgba(255,255,255,0.6)); }
        }

        .subtitle {
            color: rgba(255,255,255,0.9);
            font-size: 1.3rem;
            font-weight: 300;
            letter-spacing: 2px;
            margin-bottom: 1rem;
        }

        .feature-badges {
            display: flex;
            justify-content: center;
            gap: 1rem;
            flex-wrap: wrap;
            margin-top: 1rem;
        }

        .badge {
            padding: 0.5rem 1rem;
            background: var(--glass-bg);
            border: 1px solid var(--glass-border);
            border-radius: 20px;
            color: white;
            font-size: 0.8rem;
            font-weight: 500;
            backdrop-filter: blur(10px);
            animation: fadeInUp 0.8s ease-out;
        }

        @keyframes fadeInUp {
            from { opacity: 0; transform: translateY(20px); }
            to { opacity: 1; transform: translateY(0); }
        }

        .main-grid {
            display: grid;
            grid-template-columns: 2fr 1fr;
            gap: 2rem;
            animation: slideUp 0.8s cubic-bezier(0.25, 0.46, 0.45, 0.94) 0.2s both;
        }

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

        .main-card {
            background: rgba(255,255,255,0.95);
            backdrop-filter: blur(20px);
            border-radius: 28px;
            padding: 2.5rem;
            box-shadow: var(--shadow-heavy);
            border: 1px solid var(--glass-border);
            transition: all 0.3s ease;
            position: relative;
            overflow: hidden;
        }

        .main-card::before {
            content: '';
            position: absolute;
            top: 0;
            left: 0;
            right: 0;
            height: 4px;
            background: var(--primary-gradient);
        }

        .sidebar {
            display: flex;
            flex-direction: column;
            gap: 1.5rem;
        }

        .section-title {
            font-size: 1.8rem;
            font-weight: 700;
            color: var(--text-primary);
            margin-bottom: 1.5rem;
            display: flex;
            align-items: center;
            gap: 0.75rem;
            position: relative;
        }

        .section-title::after {
            content: '';
            position: absolute;
            bottom: -8px;
            left: 0;
            width: 60px;
            height: 3px;
            background: var(--primary-gradient);
            border-radius: 2px;
        }

        .signature-canvas-container {
            position: relative;
            background: #fff;
            border-radius: 16px;
            padding: 1rem;
            box-shadow: 0 8px 32px rgba(0,0,0,0.1);
            border: 2px dashed #e2e8f0;
            transition: all 0.3s ease;
            margin-bottom: 1rem;
        }

        .signature-canvas-container:hover {
            border-color: #667eea;
            box-shadow: 0 12px 40px rgba(102,126,234,0.15);
        }

        .signature-canvas-container.active {
            border-color: #667eea;
            border-style: solid;
            background: linear-gradient(135deg, #f8faff 0%, #f0f4ff 100%);
        }

        #signatureCanvas {
            width: 100%;
            height: 200px;
            border-radius: 12px;
            cursor: crosshair;
            touch-action: none;
        }


        .canvas-overlay {
            position: absolute;
            top: 50%;
            left: 50%;
            transform: translate(-50%, -50%);
            color: var(--text-secondary);
            font-size: 1.2rem;
            font-weight: 500;
            pointer-events: none;
            transition: all 0.3s ease;
            text-align: center;
        }

        .canvas-overlay.hidden {
            opacity: 0;
            transform: translate(-50%, -50%) scale(0.8);
        }

        .controls-grid {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
            gap: 1.5rem;
            margin-bottom: 2rem;
        }

        .control-card {
            background: linear-gradient(135deg, #f8faff 0%, #f0f4ff 100%);
            border-radius: 16px;
            padding: 1.5rem;
            border: 1px solid var(--border-color);
            transition: all 0.3s ease;
            position: relative;
            overflow: hidden;
        }

        .control-card::before {
            content: '';
            position: absolute;
            top: 0;
            left: 0;
            right: 0;
            height: 2px;
            background: var(--primary-gradient);
            transform: translateX(-100%);
            transition: transform 0.3s ease;
        }

        .control-card:hover {
            transform: translateY(-4px);
            box-shadow: var(--shadow-medium);
        }

        .control-card:hover::before {
            transform: translateX(0);
        }

        .control-title {
            font-weight: 600;
            color: var(--text-primary);
            margin-bottom: 1rem;
            display: flex;
            align-items: center;
            gap: 0.5rem;
        }

        .brush-size-container {
            display: flex;
            align-items: center;
            gap: 1rem;
        }

        .brush-size input {
            width: 100%;
            height: 8px;
            border-radius: 4px;
            background: #e2e8f0;
            outline: none;
            -webkit-appearance: none;
        }

        .brush-size input::-webkit-slider-thumb {
            -webkit-appearance: none;
            appearance: none;
            width: 20px;
            height: 20px;
            border-radius: 50%;
            background: var(--primary-gradient);
            cursor: pointer;
            box-shadow: 0 2px 8px rgba(0,0,0,0.2);
        }

        .brush-size input::-moz-range-thumb {
            width: 20px;
            height: 20px;
            border-radius: 50%;
            background: var(--primary-gradient);
            cursor: pointer;
            border: none;
            box-shadow: 0 2px 8px rgba(0,0,0,0.2);
        }

        .size-display {
            font-weight: 600;
            color: var(--text-primary);
            min-width: 40px;
            text-align: center;
        }

        .color-picker {
            display: grid;
            grid-template-columns: repeat(4, 1fr);
            gap: 0.75rem;
        }

        .color-swatch {
            width: 40px;
            height: 40px;
            border-radius: 12px;
            border: 3px solid transparent;
            cursor: pointer;
            transition: all 0.3s cubic-bezier(0.25, 0.46, 0.45, 0.94);
            position: relative;
            overflow: hidden;
        }

        .color-swatch::before {
            content: '';
            position: absolute;
            top: 50%;
            left: 50%;
            transform: translate(-50%, -50%);
            width: 0;
            height: 0;
            background: white;
            border-radius: 50%;
            transition: all 0.3s ease;
        }

        .color-swatch:hover {
            transform: scale(1.1);
            box-shadow: 0 4px 16px rgba(0,0,0,0.2);
        }

        .color-swatch.active {
            border-color: #667eea;
            box-shadow: 0 0 0 2px rgba(102,126,234,0.3);
            transform: scale(1.05);
        }

        .color-swatch.active::before {
            width: 12px;
            height: 12px;
        }

        .tool-card {
            background: rgba(255,255,255,0.95);
            backdrop-filter: blur(20px);
            border-radius: 20px;
            padding: 2rem;
            border: 1px solid var(--glass-border);
            transition: all 0.3s ease;
            box-shadow: var(--shadow-light);
            position: relative;
            overflow: hidden;
        }

        .tool-card::before {
            content: '';
            position: absolute;
            top: 0;
            left: 0;
            right: 0;
            height: 3px;
            background: var(--primary-gradient);
        }

        .tool-card:hover {
            transform: translateY(-8px);
            box-shadow: var(--shadow-heavy);
        }

        .upload-area {
            border: 2px dashed var(--border-color);
            border-radius: 16px;
            padding: 2rem;
            text-align: center;
            transition: all 0.3s ease;
            cursor: pointer;
            position: relative;
            overflow: hidden;
            background: linear-gradient(135deg, #f8faff 0%, #f0f4ff 100%);
        }

        .upload-area::before {
            content: '';
            position: absolute;
            top: 0;
            left: 0;
            right: 0;
            bottom: 0;
            background: linear-gradient(45deg, transparent 49%, rgba(102,126,234,0.05) 50%, transparent 51%);
            opacity: 0;
            transition: opacity 0.3s ease;
        }

        .upload-area:hover {
            border-color: #667eea;
            transform: scale(1.02);
        }

        .upload-area:hover::before {
            opacity: 1;
        }

        .upload-area.dragover {
            border-color: #667eea;
            background: rgba(102,126,234,0.1);
            transform: scale(1.05);
        }

        .upload-icon {
            font-size: 2.5rem;
            color: #667eea;
            margin-bottom: 1rem;
            animation: bounce 2s infinite;
        }

        @keyframes bounce {
            0%, 20%, 50%, 80%, 100% { transform: translateY(0); }
            40% { transform: translateY(-10px); }
            60% { transform: translateY(-5px); }
        }

        .upload-text {
            color: var(--text-secondary);
            font-size: 1rem;
            font-weight: 500;
        }

        .file-input {
            position: absolute;
            top: 0;
            left: 0;
            width: 100%;
            height: 100%;
            opacity: 0;
            cursor: pointer;
        }

        .action-buttons {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(120px, 1fr));
            gap: 1rem;
            margin-top: 2rem;
        }

        .btn {
            padding: 1rem 1.5rem;
            border: none;
            border-radius: 16px;
            font-weight: 600;
            cursor: pointer;
            transition: all 0.3s cubic-bezier(0.25, 0.46, 0.45, 0.94);
            text-decoration: none;
            display: inline-flex;
            align-items: center;
            justify-content: center;
            gap: 0.5rem;
            font-size: 0.95rem;
            position: relative;
            overflow: hidden;
        }

        .btn::before {
            content: '';
            position: absolute;
            top: 0;
            left: -100%;
            width: 100%;
            height: 100%;
            background: linear-gradient(90deg, transparent, rgba(255,255,255,0.3), transparent);
            transition: left 0.5s ease;
        }

        .btn:hover::before {
            left: 100%;
        }

        .btn-primary {
            background: var(--primary-gradient);
            color: white;
            box-shadow: 0 4px 16px rgba(102,126,234,0.4);
        }

        .btn-primary:hover {
            transform: translateY(-3px);
            box-shadow: 0 8px 24px rgba(102,126,234,0.5);
        }

        .btn-secondary {
            background: linear-gradient(135deg, #f7fafc 0%, #edf2f7 100%);
            color: var(--text-primary);
            border: 1px solid var(--border-color);
        }

        .btn-secondary:hover {
            background: linear-gradient(135deg, #edf2f7 0%, #e2e8f0 100%);
            transform: translateY(-3px);
            box-shadow: var(--shadow-light);
        }

        .btn-danger {
            background: var(--danger-gradient);
            color: white;
        }

        .btn-danger:hover {
            transform: translateY(-3px);
            box-shadow: 0 8px 24px rgba(245,87,108,0.4);
        }

        .btn-success {
            background: var(--success-gradient);
            color: white;
        }

        .btn-success:hover {
            transform: translateY(-3px);
            box-shadow: 0 8px 24px rgba(79,172,254,0.4);
        }

        .format-selector {
            display: flex;
            flex-direction: column;
            gap: 1rem;
            margin-bottom: 1.5rem;
        }

        .format-selector select {
            padding: 0.75rem 1rem;
            border: 2px solid var(--border-color);
            border-radius: 12px;
            background: white;
            color: var(--text-primary);
            font-weight: 500;
            cursor: pointer;
            transition: all 0.3s ease;
        }

        .format-selector select:focus {
            outline: none;
            border-color: #667eea;
            box-shadow: 0 0 0 3px rgba(102,126,234,0.2);
        }

        .stats-grid {
            display: grid;
            grid-template-columns: repeat(2, 1fr);
            gap: 1rem;
            margin-bottom: 1.5rem;
        }

        .stat-card {
            background: linear-gradient(135deg, #f8faff 0%, #f0f4ff 100%);
            border-radius: 12px;
            padding: 1rem;
            text-align: center;
            border: 1px solid var(--border-color);
        }

        .stat-number {
            font-size: 1.5rem;
            font-weight: 700;
            color: var(--text-primary);
        }

        .stat-label {
            font-size: 0.8rem;
            color: var(--text-secondary);
            margin-top: 0.25rem;
        }

        .footer {
            text-align: center;
            margin-top: 4rem;
            padding-top: 2rem;
            border-top: 1px solid rgba(255,255,255,0.1);
            animation: fadeIn 0.8s ease-out 0.8s both;
        }

        .footer-content {
            color: rgba(255,255,255,0.9);
            font-size: 0.95rem;
        }

        .footer-link {
            color: #fff;
            text-decoration: none;
            font-weight: 500;
            transition: all 0.3s ease;
            display: inline-flex;
            align-items: center;
            gap: 0.5rem;
        }

        .footer-link:hover {
            color: #f0f0f0;
            transform: translateY(-2px);
        }

        .notification {
            position: fixed;
            top: 20px;
            right: 20px;
            padding: 1rem 1.5rem;
            background: var(--success-gradient);
            color: white;
            border-radius: 16px;
            box-shadow: var(--shadow-medium);
            transform: translateX(100%);
            transition: all 0.4s cubic-bezier(0.25, 0.46, 0.45, 0.94);
            z-index: 1000;
            display: flex;
            align-items: center;
            gap: 0.5rem;
        }

        .notification.show {
            transform: translateX(0);
        }

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

        .loading {
            display: none;
            position: fixed;
            top: 50%;
            left: 50%;
            transform: translate(-50%, -50%);
            background: rgba(255,255,255,0.98);
            padding: 2.5rem;
            border-radius: 20px;
            box-shadow: var(--shadow-heavy);
            z-index: 1000;
            text-align: center;
        }

        .loading.show {
            display: block;
        }

        .spinner {
            width: 50px;
            height: 50px;
            border: 4px solid #f3f3f3;
            border-top: 4px solid #667eea;
            border-radius: 50%;
            animation: spin 1s linear infinite;
            margin: 0 auto 1rem;
        }

        @keyframes spin {
            0% { transform: rotate(0deg); }
            100% { transform: rotate(360deg); }
        }

        .advanced-tools {
            display: grid;
            grid-template-columns: 1fr;
            gap: 1rem;
            margin-top: 1.5rem;
        }

        .tool-button {
            padding: 0.75rem 1rem;
            background: linear-gradient(135deg, #f8faff 0%, #f0f4ff 100%);
            border: 1px solid var(--border-color);
            border-radius: 12px;
            cursor: pointer;
            transition: all 0.3s ease;
            display: flex;
            align-items: center;
            gap: 0.5rem;
            font-size: 0.9rem;
            font-weight: 500;
            color: var(--text-primary);
        }

        .tool-button:hover {
            background: linear-gradient(135deg, #f0f4ff 0%, #e6f3ff 100%);
            transform: translateY(-2px);
            box-shadow: var(--shadow-light);
        }

        @media (max-width: 1024px) {
            .main-grid {
                grid-template-columns: 1fr;
            }
            
            .sidebar {
                order: -1;
            }
        }

        @media (max-width: 768px) {
            .container {
                padding: 1rem;
            }
            
            .main-card {
                padding: 1.5rem;
            }
            
            .logo {
                font-size: 2.5rem;
            }
            
            .controls-grid {
                grid-template-columns: 1fr;
            }
            
            .action-buttons {
                grid-template-columns: 1fr;
            }
            
            .stats-grid {
                grid-template-columns: 1fr;
            }
        }