: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%);
    --danger-solid: #ef4444;
    --danger-solid-hover: #dc2626;
    
    --bg-primary: #ffffff;
    --bg-secondary: #f8fafc;
    --bg-tertiary: #e2e8f0;
    --text-primary: #1a202c;
    --text-secondary: #4a5568;
    --text-muted: #718096;
    --border-color: #e2e8f0;
    --shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1);

    --bg-blob-1: rgba(102, 126, 234, 0.15);
    --bg-blob-2: rgba(79, 172, 254, 0.15);
    --bg-blob-3: rgba(240, 147, 251, 0.15);
}

[data-theme="dark"] {
    --bg-primary: #1a202c;
    --bg-secondary: #2d3748;
    --bg-tertiary: #4a5568;
    --text-primary: #f7fafc;
    --text-secondary: #e2e8f0;
    --text-muted: #a0aec0;
    --border-color: #4a5568;
    --shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.3);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.3);
    --danger-solid: #f87171;
    --danger-solid-hover: #ef4444;
}

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

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    color: var(--text-primary);
    line-height: 1.6;
    transition: all 0.3s ease;
    overflow-x: hidden;
    background-color: var(--bg-secondary);
    background-image: 
        radial-gradient(circle at 15% 15%, var(--bg-blob-1), transparent 40vmin),
        radial-gradient(circle at 85% 20%, var(--bg-blob-2), transparent 40vmin),
        radial-gradient(circle at 20% 80%, var(--bg-blob-3), transparent 40vmin);
    background-repeat: no-repeat;
    background-attachment: fixed;
}

[data-theme="dark"] body {
    background-image: radial-gradient(circle at 10% 20%, #2d3748, #1a202c 90%);
}

.app-container {
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

/* Header */
.header {
    background: var(--primary-gradient);
    color: white;
    padding: 1rem 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    box-shadow: var(--shadow-lg);
    position: relative;
    z-index: 100;
}

.header-left h1 { font-size: 1.5rem; font-weight: 600; }
.header-left i { margin-right: 0.5rem; }
.header-right { display: flex; gap: 0.5rem; }

.theme-toggle, .backup-btn {
    background: rgba(255, 255, 255, 0.2);
    border: none;
    color: white;
    padding: 0.5rem;
    border-radius: 0.5rem;
    cursor: pointer;
    transition: all 0.3s ease;
    width: 40px;
    height: 40px;
}

.theme-toggle:hover, .backup-btn:hover {
    background: rgba(255, 255, 255, 0.3);
    transform: translateY(-2px);
}

/* Main Content */
.main-content {
    display: flex;
    flex: 1;
    gap: 1rem;
    padding: 1rem;
    overflow: hidden;
    height: calc(100vh - 80px);
}

/* Left Panel */
.left-panel {
    width: 350px;
    background: var(--bg-primary);
    border-radius: 1rem;
    box-shadow: var(--shadow);
    display: flex;
    flex-direction: column;
    overflow: hidden;
}

.panel-header {
    padding: 1.5rem;
    border-bottom: 1px solid var(--border-color);
}

.panel-header h3 { color: var(--text-primary); font-weight: 600; }

/* Search Section */
.search-section {
    padding: 1rem 1.5rem;
    border-bottom: 1px solid var(--border-color);
    flex-shrink: 0;
}

.search-container {
    display: flex;
    gap: 0.5rem;
    margin-bottom: 1rem;
}

.search-container input {
    flex: 1;
    padding: 0.75rem;
    border: 2px solid var(--border-color);
    border-radius: 0.5rem;
    background: var(--bg-secondary);
    color: var(--text-primary);
    transition: all 0.3s ease;
}

.search-container input:focus {
    outline: none;
    border-color: #667eea;
    box-shadow: 0 0 0 3px rgba(102, 126, 234, 0.1);
}

#addKeyword {
    background: var(--primary-gradient);
    border: none;
    color: white;
    padding: 0.75rem;
    border-radius: 0.5rem;
    cursor: pointer;
    transition: all 0.3s ease;
}

#addKeyword:hover { transform: translateY(-2px); }

.keywords-container { display: flex; flex-wrap: wrap; gap: 0.5rem; }

.keyword-tag {
    background: var(--secondary-gradient);
    color: white;
    padding: 0.25rem 0.75rem;
    border-radius: 1rem;
    font-size: 0.875rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
    animation: slideIn 0.3s ease;
}

.keyword-tag .remove-keyword {
    background: none;
    border: none;
    color: white;
    cursor: pointer;
    padding: 0;
    font-size: 0.75rem;
}

/* Lists Container */
.lists-container {
    flex: 1;
    overflow-y: auto;
    padding: 1rem 1.5rem;
}

.empty-state { text-align: center; padding: 2rem; color: var(--text-muted); }
.empty-state i { font-size: 3rem; margin-bottom: 1rem; opacity: 0.5; }

.list-item {
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    border-radius: 0.75rem;
    padding: 1rem;
    margin-bottom: 0.75rem;
    transition: all 0.3s ease;
    cursor: pointer;
}

.list-item:hover { transform: translateY(-2px); box-shadow: var(--shadow); }
.list-item.selected { border-color: #667eea; background: rgba(102, 126, 234, 0.05); }
.list-header { display: flex; justify-content: space-between; align-items: center; margin-bottom: 0.5rem; }
.list-name { font-weight: 600; color: var(--text-primary); }
.list-actions { display: flex; gap: 0.25rem; }

.action-btn {
    background: none;
    border: none;
    color: var(--text-muted);
    cursor: pointer;
    padding: 0.25rem;
    border-radius: 0.25rem;
    transition: all 0.3s ease;
}

.action-btn:hover { background: var(--bg-tertiary); color: var(--text-primary); }
.action-btn.download { color: #4facfe; }
.action-btn.delete { color: #fa709a; }
.list-info { font-size: 0.875rem; color: var(--text-muted); }

/* Right Panel */
.right-panel {
    flex: 1;
    background: var(--bg-primary);
    border-radius: 1rem;
    box-shadow: var(--shadow);
    overflow: hidden;
    display: flex;
    flex-direction: column;
}

/* Upload Section */
.upload-section { padding: 2rem; flex: 1; display: flex; align-items: center; justify-content: center; }

.upload-area {
    border: 2px dashed var(--border-color);
    border-radius: 1rem;
    padding: 3rem;
    text-align: center;
    cursor: pointer;
    transition: all 0.3s ease;
    background: var(--bg-secondary);
    width: 100%;
    max-width: 500px;
}

.upload-area:hover, .upload-area.dragover { border-color: #667eea; background: rgba(102, 126, 234, 0.1); }
.upload-content i { font-size: 3rem; color: var(--text-muted); margin-bottom: 1rem; }
.upload-content h3 { color: var(--text-primary); margin-bottom: 0.5rem; }
.upload-content p { color: var(--text-muted); margin-bottom: 1.5rem; }

.upload-btn {
    background: var(--primary-gradient);
    border: none;
    color: white;
    padding: 0.75rem 1.5rem;
    border-radius: 0.5rem;
    cursor: pointer;
    font-weight: 600;
    transition: all 0.3s ease;
}

.upload-btn:hover { transform: translateY(-2px); box-shadow: var(--shadow); }

/* Preview Section */
.preview-section { flex: 1; display: flex; flex-direction: column; overflow: hidden; height: 100%; }

.preview-header {
    padding: 1.5rem;
    border-bottom: 1px solid var(--border-color);
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    flex-shrink: 0;
    flex-wrap: wrap;
    gap: 1rem;
}

.preview-header-left { display: flex; flex-direction: column; gap: 1rem; }
.preview-header-left h3 { color: var(--text-primary); font-weight: 600; }

.preview-stats {
    color: var(--text-muted);
    font-size: 0.875rem;
    font-weight: 500;
    display: flex;
    gap: 1rem;
    background: var(--bg-secondary);
    padding: 0.5rem 1rem;
    border-radius: 0.5rem;
}

#selectionCountStat {
    color: #667eea;
    font-weight: 600;
    border-left: 2px solid var(--border-color);
    padding-left: 1rem;
}

.preview-actions { display: flex; gap: 0.5rem; flex-wrap: wrap; align-items: center; }

.preview-header-right {
    display: flex;
    gap: 0.5rem;
    align-items: center;
}

.action-btn-main, .clear-all-btn, .delete-selected-btn, .create-list-btn {
    background: var(--bg-secondary);
    border: 1px solid var(--border-color);
    color: var(--text-secondary);
    padding: 0.5rem 1rem;
    border-radius: 0.5rem;
    cursor: pointer;
    font-size: 0.875rem;
    transition: all 0.3s ease;
    font-weight: 500;
}

.action-btn-main:hover, .clear-all-btn:hover, .delete-selected-btn:hover, .create-list-btn:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow);
}

.action-btn-main.primary {
    background: var(--primary-gradient);
    color: white;
    border: none;
}

.clear-all-btn { background: var(--secondary-gradient); color: white; border: none; }
.create-list-btn { background: var(--success-gradient); color: white; border: none; }

.delete-selected-btn {
    background: var(--danger-solid);
    color: white;
    border: none;
}
.delete-selected-btn:hover {
    background: var(--danger-solid-hover);
}


/* Table Container */
.table-container { 
    flex: 1; 
    padding: 1.5rem;
    padding-top: 0;
    display: flex; 
    flex-direction: column; 
    overflow: hidden; 
}
.table-wrapper { flex: 1; overflow: auto; border: 1px solid var(--border-color); border-radius: 0.5rem; position: relative; max-height: 100%; }
.data-table { width: 100%; border-collapse: collapse; font-size: 0.875rem; min-width: 100%; }

.data-table th, .data-table td {
    padding: 0.75rem;
    text-align: left;
    border-bottom: 1px solid var(--border-color);
    white-space: nowrap;
    border-right: 1px solid var(--border-color);
}

.data-table th:last-child, .data-table td:last-child { border-right: none; }

.data-table th {
    background: var(--bg-secondary);
    font-weight: 600;
    color: var(--text-primary);
    position: sticky;
    top: 0;
    z-index: 10;
}

.data-table th .empty-filter-icon { margin-left: 8px; cursor: pointer; color: var(--text-muted); transition: color 0.2s ease; }
.data-table th .empty-filter-icon:hover { color: var(--text-primary); }
.data-table th .empty-filter-icon.active { color: #667eea; }

.data-table tbody tr:hover { background: var(--bg-secondary); }
.data-table tbody tr.selected { background: rgba(102, 126, 234, 0.1); }
.data-table tbody tr.duplicate-row { background-color: rgba(251, 113, 133, 0.2); }
.data-table tbody tr.reference-match-row { background-color: rgba(79, 172, 254, 0.2); }

[data-theme="dark"] .data-table tbody tr.duplicate-row { background-color: rgba(155, 44, 44, 0.4); }
[data-theme="dark"] .data-table tbody tr.reference-match-row { background-color: rgba(79, 172, 254, 0.3); }

.data-table td[contenteditable="true"]:focus {
    background-color: rgba(102, 126, 234, 0.1);
    outline: 2px solid #667eea;
    box-shadow: 0 0 5px rgba(102, 126, 234, 0.3);
}

.checkbox-cell { width: 50px; text-align: center; position: sticky; left: 0; background: inherit; z-index: 5; padding: 0.5rem; }
.data-table th.checkbox-cell { z-index: 15; background: var(--bg-secondary); }
.data-table tbody tr .checkbox-cell { background: var(--bg-primary); }
.data-table tbody tr:hover .checkbox-cell { background: var(--bg-secondary); }
.data-table tbody tr.selected .checkbox-cell { background: rgba(102, 126, 234, 0.1); }
.data-table tbody tr.duplicate-row .checkbox-cell,
.data-table tbody tr.reference-match-row .checkbox-cell { background: inherit; }

.row-checkbox, #selectAllCheckbox { cursor: pointer; transform: scale(1.2); accent-color: #667eea; }

.highlight {
    background: linear-gradient(135deg, #f093fb 0%, #f5576c 100%);
    color: white;
    padding: 0.125rem 0.25rem;
    border-radius: 0.25rem;
    font-weight: 600;
}

/* Modals */
.modal { display: none; position: fixed; top: 0; left: 0; width: 100%; height: 100%; background: rgba(0, 0, 0, 0.5); z-index: 1000; animation: fadeIn 0.3s ease; }
.modal-content { background: var(--bg-primary); margin: 5% auto; border-radius: 1rem; max-width: 500px; box-shadow: var(--shadow-lg); animation: slideUp 0.3s ease; }
.modal-header { padding: 1.5rem; border-bottom: 1px solid var(--border-color); display: flex; justify-content: space-between; align-items: center; }
.modal-header h3 { color: var(--text-primary); font-weight: 600; }

.close-btn {
    background: none;
    border: none;
    font-size: 1.5rem;
    cursor: pointer;
    color: var(--text-muted);
    padding: 0;
    width: 30px;
    height: 30px;
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 50%;
    transition: all 0.3s ease;
}

.close-btn:hover { background: var(--bg-secondary); color: var(--text-primary); }
.modal-body { padding: 1.5rem; }

.modal-body input[type="text"], .modal-select {
    width: 100%;
    padding: 0.75rem;
    border: 2px solid var(--border-color);
    border-radius: 0.5rem;
    background: var(--bg-secondary);
    color: var(--text-primary);
    margin-bottom: 1rem;
    transition: all 0.3s ease;
}

.modal-body input[type="text"]:focus, .modal-select:focus {
    outline: none;
    border-color: #667eea;
    box-shadow: 0 0 0 3px rgba(102, 126, 234, 0.1);
}

.modal-footer { padding: 1.5rem; border-top: 1px solid var(--border-color); display: flex; gap: 0.75rem; justify-content: flex-end; }

.cancel-btn, .save-btn { padding: 0.75rem 1.5rem; border-radius: 0.5rem; cursor: pointer; transition: all 0.3s ease; font-weight: 600; }
.cancel-btn { background: var(--bg-secondary); border: 1px solid var(--border-color); color: var(--text-secondary); }
.cancel-btn:hover { background: var(--bg-tertiary); color: var(--text-primary); }
.save-btn { background: var(--success-gradient); border: none; color: white; }
.save-btn:hover { transform: translateY(-2px); box-shadow: var(--shadow); }

.format-options { display: flex; gap: 1rem; margin-top: 1rem; }
.format-btn { flex: 1; background: var(--bg-secondary); border: 2px solid var(--border-color); color: var(--text-primary); padding: 1rem; border-radius: 0.75rem; cursor: pointer; text-align: center; transition: all 0.3s ease; }
.format-btn:hover { border-color: #667eea; background: rgba(102, 126, 234, 0.05); transform: translateY(-2px); }
.format-btn i { font-size: 2rem; margin-bottom: 0.5rem; display: block; color: var(--text-muted); }
.format-btn small { display: block; font-size: 0.75rem; color: var(--text-muted); margin-top: 0.25rem; }

.columns-container { max-height: 200px; overflow-y: auto; border: 1px solid var(--border-color); border-radius: 0.5rem; padding: 1rem; background: var(--bg-secondary); }
.column-checkbox { display: block; margin-bottom: 0.75rem; }
.column-checkbox label { margin-left: 0.5rem; cursor: pointer; }

/* Animations */
@keyframes fadeIn { from { opacity: 0; } to { opacity: 1; } }
@keyframes slideUp { from { opacity: 0; transform: translateY(50px); } to { opacity: 1; transform: translateY(0); } }
@keyframes slideIn { from { opacity: 0; transform: translateX(-20px); } to { opacity: 1; transform: translateX(0); } }
@keyframes fadeOut { from { opacity: 1; transform: translateX(0); } to { opacity: 0; transform: translateX(100%); } }

/* Scrollbar Styling */
::-webkit-scrollbar { width: 8px; height: 8px; }
::-webkit-scrollbar-track { background: var(--bg-secondary); border-radius: 4px; }
::-webkit-scrollbar-thumb { background: var(--text-muted); border-radius: 4px; }
::-webkit-scrollbar-thumb:hover { background: var(--text-secondary); }

/* Responsive */
@media (max-width: 768px) {
    .main-content { flex-direction: column; height: auto; overflow: visible; }
    .left-panel { width: 100%; order: 2; max-height: 400px; }
    .right-panel { order: 1; min-height: 300px; }
    .header { padding: 1rem; }
    .header-left h1 { font-size: 1.25rem; }
    .table-wrapper { max-height: 300px; }
}