:root {
     --bg-primary: #f8f9fa;
     --bg-secondary: #f1f3f5;
     --bg-card: #ffffff;
     --bg-card-hover: #ffffff;
     --border-color: #dee2e6;
     --text-primary: #212529;
     --text-secondary: #495057;
     --text-muted: #adb5bd;
     --accent-primary: #007aff;
     --accent-secondary: #0056b3;
     --accent-gradient: var(--accent-primary);
     --success: #10b981;
     --success-gradient: var(--success);
     --warning: #f59e0b;
     --error: #ef4444;
     --radius-sm: 8px;
     --radius-md: 12px;
     --radius-lg: 16px;
     --radius-xl: 24px;
     --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
     --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
     --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
     --shadow-glow: 0 0 15px rgba(0, 122, 255, 0.2);
     --transition-fast: 0.15s ease;
     --transition-normal: 0.3s ease;
     --transition-slow: 0.5s ease;
 }

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

 body {
     font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
     background: var(--bg-primary);
     color: var(--text-primary);
     min-height: 100vh;
     line-height: 1.6;
     overflow-x: hidden;
 }



 .container {
     max-width: 1400px;
     margin: 0 auto;
     padding: 40px 20px;
 }

 /* Layout Grid */
 .layout-grid {
     display: grid;
     grid-template-columns: 380px 1fr;
     gap: 24px;
     align-items: start;
 }

 .layout-left {
     display: flex;
     flex-direction: column;
 }

 .layout-right {
     min-width: 0;
 }

 /* Header */
 .header {
     text-align: center;
     margin-bottom: 40px;
 }

 .logo {
     display: flex;
     align-items: center;
     justify-content: center;
     gap: 12px;
     margin-bottom: 12px;
 }

 .logo svg {
     width: 40px;
     height: 40px;
     color: var(--accent-primary);
     filter: drop-shadow(0 0 20px rgba(0, 122, 255, 0.5));
 }

 .logo h1 {
     font-size: 2rem;
     font-weight: 700;
     color: var(--accent-primary);
 }

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

 /* Cards */
 .card {
     background: var(--bg-card);
     border: 1px solid var(--border-color);
     border-radius: var(--radius-lg);
     padding: 24px;
     margin-bottom: 20px;
     backdrop-filter: blur(20px);
     transition: all var(--transition-normal);
 }

 .card:hover {
     background: var(--bg-card-hover);
     border-color: rgba(0, 122, 255, 0.2);
 }

 .card h2 {
     display: flex;
     align-items: center;
     gap: 12px;
     font-size: 1.1rem;
     font-weight: 600;
     margin-bottom: 20px;
     color: var(--text-primary);
 }

 .step-number {
     display: flex;
     align-items: center;
     justify-content: center;
     width: 28px;
     height: 28px;
     background: var(--accent-gradient);
     border-radius: 50%;
     font-size: 0.85rem;
     font-weight: 700;
 }

 /* Form Elements */
 .form-row {
     display: grid;
     grid-template-columns: 1fr;
     gap: 16px;
     margin-bottom: 20px;
 }

 .form-group {
     display: flex;
     flex-direction: column;
     gap: 8px;
 }

 .form-group label {
     font-size: 0.85rem;
     font-weight: 500;
     color: var(--text-secondary);
 }

 input,
 select {
     width: 100%;
     padding: 12px 16px;
     background: var(--bg-secondary);
     border: 1px solid var(--border-color);
     border-radius: var(--radius-md);
     color: var(--text-primary);
     font-size: 0.95rem;
     font-family: inherit;
     transition: all var(--transition-fast);
     outline: none;
 }

 input::placeholder {
     color: var(--text-muted);
 }

 input:focus,
 select:focus {
     border-color: var(--accent-primary);
     box-shadow: 0 0 0 3px rgba(0, 122, 255, 0.15);
 }

 select {
     cursor: pointer;
     appearance: none;
     background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='24' height='24' viewBox='0 0 24 24' fill='none' stroke='rgba(0,0,0,0.5)' stroke-width='2'%3E%3Cpolyline points='6 9 12 15 18 9'%3E%3C/polyline%3E%3C/svg%3E");
     background-repeat: no-repeat;
     background-position: right 12px center;
     background-size: 16px;
     padding-right: 40px;
 }

 select option {
     background: var(--bg-secondary);
     color: var(--text-primary);
 }

 /* Buttons */
 .btn {
     display: inline-flex;
     align-items: center;
     justify-content: center;
     gap: 8px;
     padding: 12px 24px;
     border: none;
     border-radius: var(--radius-md);
     font-size: 0.95rem;
     font-weight: 600;
     font-family: inherit;
     cursor: pointer;
     transition: all var(--transition-fast);
     outline: none;
 }

 .btn svg {
     width: 18px;
     height: 18px;
 }

 .btn-primary {
     background: var(--accent-gradient);
     color: white;
     box-shadow: var(--shadow-sm), 0 0 20px rgba(0, 122, 255, 0.3);
     width: 100%;
 }

 .btn-primary:hover:not(:disabled) {
     transform: translateY(-2px);
     box-shadow: var(--shadow-md), var(--shadow-glow);
 }

 .btn-primary:disabled {
     opacity: 0.5;
     cursor: not-allowed;
 }

 .btn-success {
     background: var(--success-gradient);
     color: white;
     box-shadow: var(--shadow-sm), 0 0 20px rgba(16, 185, 129, 0.3);
 }

 .btn-success:hover {
     transform: translateY(-2px);
     box-shadow: var(--shadow-md), 0 0 40px rgba(16, 185, 129, 0.4);
 }

 .btn-large {
     padding: 16px 32px;
     font-size: 1.05rem;
 }

 .btn-small {
     padding: 8px 16px;
     font-size: 0.85rem;
     background: var(--bg-secondary);
     color: var(--text-secondary);
     border: 1px solid var(--border-color);
 }

 .btn-small:hover {
     background: var(--bg-card-hover);
     color: var(--text-primary);
     border-color: var(--accent-primary);
 }

 /* Model List */
 .model-list {
     display: grid;
     gap: 8px;
     max-height: 400px;
     overflow-y: auto;
 }

 .model-item {
     display: flex;
     align-items: center;
     gap: 12px;
     padding: 14px 16px;
     background: var(--bg-secondary);
     border: 1px solid var(--border-color);
     border-radius: var(--radius-md);
     cursor: pointer;
     transition: all var(--transition-fast);
 }

 .model-item:hover {
     background: var(--bg-card-hover);
     border-color: var(--accent-primary);
 }

 .model-item.selected {
     background: rgba(0, 122, 255, 0.15);
     border-color: var(--accent-primary);
 }

 .model-icon {
     width: 36px;
     height: 36px;
     display: flex;
     align-items: center;
     justify-content: center;
     background: var(--accent-gradient);
     border-radius: var(--radius-sm);
     font-size: 1.2rem;
 }

 .model-info {
     flex: 1;
 }

 .model-name {
     font-weight: 500;
     font-size: 0.95rem;
 }

 .model-code {
     font-size: 0.8rem;
     color: var(--text-muted);
 }

 /* Driver Toolbar */
 .driver-toolbar {
     display: flex;
     align-items: center;
     justify-content: space-between;
     margin-bottom: 16px;
     padding-bottom: 16px;
     border-bottom: 1px solid var(--border-color);
 }

 .select-actions {
     display: flex;
     gap: 8px;
 }

 .selected-count {
     font-size: 0.9rem;
     color: var(--accent-primary);
     font-weight: 500;
 }

 /* Driver Categories */
 .driver-categories {
     display: flex;
     flex-direction: column;
     gap: 12px;
     max-height: none;
     overflow-y: visible;
 }

 .driver-category {
     position: relative;
     background: var(--bg-secondary);
     border: 1px solid var(--border-color);
     border-radius: var(--radius-md);
     overflow: visible;
 }

 .category-header {
     display: flex;
     align-items: center;
     justify-content: space-between;
     padding: 14px 16px;
     cursor: pointer;
     transition: all var(--transition-fast);
 }

 .category-header:hover {
     background: var(--bg-card-hover);
     border-radius: var(--radius-md);
 }

 .category-title {
     display: flex;
     align-items: center;
     gap: 10px;
     font-weight: 500;
 }

 .category-icon {
     font-size: 1.2rem;
 }

 .category-count {
     font-size: 0.8rem;
     padding: 2px 8px;
     background: rgba(0, 122, 255, 0.2);
     color: var(--accent-primary);
     border-radius: 12px;
 }

 .category-toggle {
     width: 24px;
     height: 24px;
     display: flex;
     align-items: center;
     justify-content: center;
     color: var(--text-muted);
     transition: transform var(--transition-fast);
 }

 .driver-category.expanded .category-toggle {
     transform: rotate(180deg);
 }

 .category-drivers {
     display: none;
     padding: 0 16px 16px;
 }

 .driver-category.expanded .category-drivers {
     display: block;
 }

 /* Driver Items */
 .driver-item {
     display: flex;
     align-items: flex-start;
     gap: 12px;
     padding: 12px;
     margin-top: 8px;
     background: var(--bg-card);
     border: 1px solid var(--border-color);
     border-radius: var(--radius-sm);
     cursor: pointer;
     transition: all var(--transition-fast);
 }

 .driver-item:hover {
     border-color: rgba(0, 122, 255, 0.3);
 }

 .driver-item.selected {
     background: rgba(0, 122, 255, 0.1);
     border-color: var(--accent-primary);
 }

 /* Custom Checkbox */
 .checkbox {
     flex-shrink: 0;
     width: 20px;
     height: 20px;
     border: 2px solid var(--border-color);
     border-radius: 4px;
     display: flex;
     align-items: center;
     justify-content: center;
     transition: all var(--transition-fast);
 }

 .driver-item.selected .checkbox {
     background: var(--accent-gradient);
     border-color: transparent;
 }

 .checkbox svg {
     width: 12px;
     height: 12px;
     color: white;
     opacity: 0;
     transform: scale(0.5);
     transition: all var(--transition-fast);
 }

 .driver-item.selected .checkbox svg {
     opacity: 1;
     transform: scale(1);
 }

 .driver-info {
     flex: 1;
     min-width: 0;
 }

 .driver-name {
     font-size: 0.9rem;
     font-weight: 500;
     word-break: break-all;
 }

 .driver-size {
     font-size: 0.8rem;
     color: var(--text-muted);
     margin-top: 4px;
 }

 /* Download Section */
 .download-section {
     position: sticky;
     bottom: 20px;
     background: var(--bg-card);
     border: 1px solid rgba(16, 185, 129, 0.3);
     box-shadow: var(--shadow-lg), 0 0 40px rgba(16, 185, 129, 0.2);
     z-index: 100;
 }

 .download-summary {
     display: flex;
     align-items: center;
     justify-content: space-between;
     gap: 20px;
 }

 .summary-info {
     display: flex;
     align-items: center;
     gap: 12px;
 }

 .download-icon {
     font-size: 1.5rem;
 }

 #downloadSummary {
     font-size: 0.95rem;
     color: var(--text-secondary);
 }

 /* Loading Overlay */
 .loading-overlay {
     position: fixed;
     top: 0;
     left: 0;
     right: 0;
     bottom: 0;
     background: rgba(10, 10, 15, 0.9);
     display: flex;
     flex-direction: column;
     align-items: center;
     justify-content: center;
     gap: 20px;
     z-index: 1000;
     backdrop-filter: blur(8px);
 }

 .spinner {
     width: 48px;
     height: 48px;
     border: 3px solid var(--border-color);
     border-top-color: var(--accent-primary);
     border-radius: 50%;
     animation: spin 1s linear infinite;
 }

 @keyframes spin {
     to {
         transform: rotate(360deg);
     }
 }

 #loadingText {
     color: var(--text-secondary);
     font-size: 0.95rem;
 }

 /* Toast */
 .toast-container {
     position: fixed;
     bottom: 20px;
     left: 50%;
     transform: translateX(-50%);
     z-index: 1100;
     display: flex;
     flex-direction: column;
     gap: 10px;
 }

 .toast {
     padding: 14px 20px;
     background: var(--bg-card);
     border: 1px solid var(--border-color);
     border-radius: var(--radius-md);
     backdrop-filter: blur(20px);
     box-shadow: var(--shadow-md);
     animation: slideUp 0.3s ease;
 }

 .toast.success {
     border-color: rgba(16, 185, 129, 0.5);
 }

 .toast.error {
     border-color: rgba(239, 68, 68, 0.5);
 }

 @keyframes slideUp {
     from {
         opacity: 0;
         transform: translateY(20px);
     }

     to {
         opacity: 1;
         transform: translateY(0);
     }
 }

 /* Hidden utility */
 .hidden {
     display: none !important;
 }

 /* Scrollbar */
 ::-webkit-scrollbar {
     width: 8px;
 }

 ::-webkit-scrollbar-track {
     background: var(--bg-secondary);
     border-radius: 4px;
 }

 ::-webkit-scrollbar-thumb {
     background: var(--border-color);
     border-radius: 4px;
 }

 ::-webkit-scrollbar-thumb:hover {
     background: rgba(255, 255, 255, 0.15);
 }

 /* Responsive */
 @media (max-width: 900px) {
     .layout-grid {
         grid-template-columns: 1fr;
     }

     .container {
         padding: 20px 16px;
     }

     .form-row {
         grid-template-columns: 1fr;
     }

     .download-section {
         bottom: 10px;
         position: fixed;
         left: 20px;
         right: 20px;
     }
 }

 /* Utilities */
 .form-text {
     font-size: 0.85rem;
     margin-top: 6px;
 }

 .text-warning {
     color: var(--warning);
 }