:root {
            --primary: #206BC4;
            --primary-hover: #1a56a0;
            --bg: #f8f9fa;
            --card-bg: #ffffff;
            --text: #2d3436;
            --text-light: #636e72;
            --border: #dfe6e9;
            --radius: 8px;
            --shadow: 0 4px 6px rgba(0,0,0,0.05);
        }

        * { box-sizing: border-box; font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif; }
        .container { max-width: 1100px; margin: 0 auto; }

        /* Upload Area */
        .upload-zone {
            background: var(--card-bg);
            border: 2px dashed var(--border);
            border-radius: var(--radius);
            padding: 40px;
            text-align: center;
            cursor: pointer;
            transition: all 0.3s ease;
            margin: 2rem;
        }
        .upload-zone:hover, .upload-zone.dragover { border-color: var(--primary); background: #f0f7ff; }
        .upload-zone svg { width: 50px; fill: var(--text-light); margin-bottom: 15px; }
        #fileInput { display: none; }

        /* Main App Grid */
        .app-grid { display: grid; grid-template-columns: 1fr 350px; gap: 1rem; display: none; }
        @media (max-width: 992px) { .app-grid { grid-template-columns: 1fr; } .site-header { padding: 0 1rem; } }

        /* Preview Area */
        .preview-card {
            background: var(--card-bg);
            border-radius: var(--radius);
            padding: 20px;
            box-shadow: var(--shadow);
            position: relative;
        }
        .comparison-container {
            position: relative;
            width: 100%;
            height: 300px;
            overflow: hidden;
            background: #fff;
            border-radius: 4px;
            background-size: 20px 20px;
            background-position: 0 0, 0 10px, 10px -10px, -10px 0px;
        }
        .comparison-slider {
            position: absolute;
            top: 0; left: 0; width: 100%; height: 100%;
            object-fit: contain;
        }
        .after-image {
            position: absolute;
            top: 0; left: 0; width: 100%; height: 100%;
            clip-path: inset(0 0 0 50%);
        }
        .slider-handle {
            position: absolute;
            top: 0; bottom: 0; left: 50%;
            width: 4px; background: #206bc4;
            cursor: ew-resize; transform: translateX(-50%);
            z-index: 10; box-shadow: 0 0 10px rgba(0,0,0,0.3);
        }
        .slider-input {
            position: absolute;
            top: 0; left: 0; width: 100%; height: 100%;
            opacity: 0; cursor: ew-resize; z-index: 20;
        }

        /* Controls */
        .controls-card {
            background: var(--card-bg);
            padding: 25px;
            border-radius: var(--radius);
            box-shadow: var(--shadow);
            height: fit-content;
        }
        .control-group { margin-bottom: 20px; }
        label { display: block; font-weight: 600; margin-bottom: 8px; font-size: 0.9rem; }
        
        .btn-group { display: grid; grid-template-columns: repeat(3, 1fr); gap: 8px; }
        .btn-group button {
            padding: 8px;
            border: 1px solid var(--border);
            background: white;
            cursor: pointer;
            border-radius: 4px;
            font-size: 0.85rem;
        }
        .btn-group button.active { background: var(--primary); color: white; border-color: var(--primary); }

        .input-row { display: grid; grid-template-columns: 1fr 1fr; gap: 10px; }
        input[type="number"], select {
            width: 100%; padding: 10px;
            border: 1px solid var(--border);
            border-radius: 4px; outline: none;
        }
        
        .toggle-container { display: flex; align-items: center; gap: 10px; cursor: pointer; }
        .toggle-container input { cursor: pointer; }

        .action-btns { margin-top: 30px; display: flex; flex-direction: column; gap: 10px; }
        .btn-main {
            background: var(--primary);
            color: white;
            border: none;
            padding: 15px;
            border-radius: var(--radius);
            font-weight: bold;
            cursor: pointer;
            transition: background 0.2s;
            text-align: center;
            text-decoration: none;
        }
        .btn-main:hover { background: var(--primary-hover); }
        .btn-reset { background: #f1f2f6; color: var(--text); border: none; padding: 10px; cursor: pointer; border-radius: var(--radius); }

        /* Batch Styles */
        .batch-list { margin-top: 30px; background: white; border-radius: var(--radius); padding: 20px; display: none; }
        .batch-item { display: flex; justify-content: space-between; align-items: center; padding: 10px; border-bottom: 1px solid var(--border); }
        .batch-item:last-child { border-bottom: none; }

        /* Utilities */
        .hidden { display: none; }
        .badge { background: #e1f0ff; color: var(--primary); padding: 2px 8px; border-radius: 4px; font-size: 0.75rem; }