:root {
    --primary: #132190;
    --primary-hover: #0d1660;
    --primary-light: rgba(19, 33, 144, 0.1);
    --success: #10b981;
    --success-light: rgba(16, 185, 129, 0.1);
    --warning: #f59e0b;
    --warning-light: rgba(245, 158, 11, 0.1);
    --error: #ef4444;
    --error-light: rgba(239, 68, 68, 0.1);
    --gray-50: #f9fafb;
    --gray-100: #f3f4f6;
    --gray-200: #e5e7eb;
    --gray-300: #d1d5db;
    --gray-400: #9ca3af;
    --gray-500: #6b7280;
    --gray-600: #4b5563;
    --gray-700: #374151;
    --gray-800: #1f2937;
    --gray-900: #111827;
    --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), 0 2px 4px -2px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1), 0 4px 6px -4px rgba(0, 0, 0, 0.1);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1), 0 8px 10px -6px rgba(0, 0, 0, 0.1);
    --transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    background: linear-gradient(135deg, #f5f7fa 0%, #e4e8ec 100%);
    color: var(--gray-800);
    line-height: 1.6;
    min-height: 100vh;
    -webkit-font-smoothing: antialiased;
}

.app-container {
    max-width: 1100px;
    margin: 0 auto;
    padding: 2rem 1.5rem;
}

/* Header */
.header {
    text-align: center;
    margin-bottom: 3rem;
    display: flex;
    flex-direction: column;
    align-items: center;
}

.back-link,
.back-link:visited,
.back-link:link {
    display: inline-flex;
    align-items: center;
    align-self: flex-start;
    gap: 0.5rem;
    color: var(--gray-500);
    text-decoration: none;
    font-size: 0.875rem;
    font-weight: 500;
    margin-bottom: 1.5rem;
    transition: var(--transition);
}

.back-link:hover {
    color: var(--primary);
}

.header-icon {
    width: 64px;
    height: 64px;
    background: linear-gradient(135deg, #010451 0%, var(--primary) 100%);
    border-radius: var(--radius-lg);
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto 1.5rem;
    box-shadow: var(--shadow-lg);
}

.header-icon svg {
    width: 32px;
    height: 32px;
    color: white;
}

.header h1 {
    font-size: 2rem;
    font-weight: 700;
    color: var(--gray-900);
    margin-bottom: 0.5rem;
    letter-spacing: -0.025em;
}

.header p {
    color: var(--gray-500);
    font-size: 1.05rem;
}

/* Steps */
.steps-container {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.step {
    background: white;
    border-radius: var(--radius-lg);
    padding: 1.75rem;
    box-shadow: var(--shadow-md);
    border: 1px solid var(--gray-100);
    transition: var(--transition);
}

.step:hover {
    box-shadow: var(--shadow-lg);
}

.step-header {
    display: flex;
    align-items: center;
    gap: 1rem;
    margin-bottom: 1.25rem;
}

.step-number {
    width: 32px;
    height: 32px;
    background: var(--primary-light);
    color: var(--primary);
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-weight: 600;
    font-size: 0.875rem;
    flex-shrink: 0;
}

.step-title {
    font-size: 1.1rem;
    font-weight: 600;
    color: var(--gray-800);
}

.step-description {
    font-size: 0.875rem;
    color: var(--gray-500);
    margin-left: auto;
}

/* Toggle buttons (2/3 files) */
.toggle-group {
    display: flex;
    background: var(--gray-100);
    border-radius: var(--radius-md);
    padding: 4px;
    gap: 4px;
}

.toggle-btn {
    flex: 1;
    padding: 0.75rem 1.5rem;
    border: none;
    background: transparent;
    border-radius: var(--radius-sm);
    font-size: 0.9rem;
    font-weight: 500;
    color: var(--gray-600);
    cursor: pointer;
    transition: var(--transition);
}

.toggle-btn:hover {
    color: var(--gray-800);
}

.toggle-btn.active {
    background: white;
    color: var(--gray-900);
    box-shadow: var(--shadow-sm);
}

/* File upload */
.file-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 1rem;
}

.file-upload {
    position: relative;
    border: 2px dashed var(--gray-300);
    border-radius: var(--radius-md);
    padding: 2rem 1.5rem;
    text-align: center;
    transition: var(--transition);
    cursor: pointer;
    background: var(--gray-50);
}

.file-upload:hover {
    border-color: var(--primary);
    background: var(--primary-light);
}

.file-upload.dragover {
    border-color: var(--primary);
    background: var(--primary-light);
    transform: scale(1.02);
}

.file-upload.has-file {
    border-color: var(--success);
    border-style: solid;
    background: var(--success-light);
}

.file-upload input {
    display: none;
}

.file-upload-icon {
    width: 48px;
    height: 48px;
    margin: 0 auto 1rem;
    color: var(--gray-400);
    transition: var(--transition);
}

.file-upload:hover .file-upload-icon {
    color: var(--primary);
}

.file-upload.has-file .file-upload-icon {
    color: var(--success);
}

.file-upload-label {
    font-weight: 600;
    color: var(--gray-700);
    margin-bottom: 0.25rem;
    font-size: 0.95rem;
}

.file-upload-hint {
    font-size: 0.8rem;
    color: var(--gray-600);
}

.file-upload-status {
    margin-top: 0.75rem;
    font-size: 0.85rem;
    color: var(--success);
    font-weight: 500;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.35rem;
}

.file-badge {
    position: absolute;
    top: 0.75rem;
    right: 0.75rem;
    background: var(--primary);
    color: white;
    font-size: 0.7rem;
    font-weight: 600;
    padding: 0.25rem 0.5rem;
    border-radius: 9999px;
    text-transform: uppercase;
    letter-spacing: 0.025em;
}

/* Key column select */
.key-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 1rem;
}

.select-group {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.select-label {
    font-size: 0.8rem;
    font-weight: 500;
    color: var(--gray-600);
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.select-wrapper {
    position: relative;
}

.select-wrapper select {
    width: 100%;
    padding: 0.75rem 2.5rem 0.75rem 1rem;
    border: 1px solid var(--gray-200);
    border-radius: var(--radius-sm);
    font-size: 0.9rem;
    color: var(--gray-800);
    background: white;
    cursor: pointer;
    appearance: none;
    transition: var(--transition);
}

.select-wrapper select:hover {
    border-color: var(--gray-300);
}

.select-wrapper select:focus {
    outline: none;
    border-color: var(--primary);
    box-shadow: 0 0 0 3px var(--primary-light);
}

.select-wrapper::after {
    content: '';
    position: absolute;
    right: 1rem;
    top: 50%;
    transform: translateY(-50%);
    width: 0;
    height: 0;
    border-left: 5px solid transparent;
    border-right: 5px solid transparent;
    border-top: 5px solid var(--gray-400);
    pointer-events: none;
}

/* Key column preview */
.key-preview {
    margin-top: 0.5rem;
    padding: 0.5rem 0.75rem;
    background: var(--gray-50);
    border: 1px solid var(--gray-200);
    border-radius: var(--radius-sm);
    font-size: 0.75rem;
    color: var(--gray-600);
    line-height: 1.4;
}

.key-preview .preview-label {
    font-weight: 600;
    color: var(--gray-700);
}

.key-preview .preview-empty {
    color: var(--warning);
    font-style: italic;
}

/* Column selection */
.column-expander {
    border: 1px solid var(--gray-200);
    border-radius: var(--radius-md);
    overflow: hidden;
    margin-bottom: 0.75rem;
    transition: var(--transition);
}

.column-expander:hover {
    border-color: var(--gray-300);
}

.column-expander-header {
    padding: 1rem 1.25rem;
    background: var(--gray-50);
    cursor: pointer;
    display: flex;
    justify-content: space-between;
    align-items: center;
    transition: var(--transition);
}

.column-expander-header:hover {
    background: var(--gray-100);
}

.column-expander-title {
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.column-expander-title span {
    font-weight: 500;
    color: var(--gray-700);
}

.column-count {
    font-size: 0.75rem;
    color: var(--gray-500);
    background: var(--gray-200);
    padding: 0.2rem 0.5rem;
    border-radius: 9999px;
}

.expander-arrow {
    width: 20px;
    height: 20px;
    color: var(--gray-400);
    transition: var(--transition);
}

.expander-arrow.open {
    transform: rotate(180deg);
}

.column-expander-content {
    padding: 1.25rem;
    display: none;
    border-top: 1px solid var(--gray-200);
    background: white;
}

.column-expander-content.open {
    display: block;
}

/* Checkbox styling */
.checkbox-wrapper {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    margin-bottom: 1rem;
    padding: 0.75rem 1rem;
    background: var(--primary-light);
    border-radius: var(--radius-sm);
}

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

.checkbox-wrapper label {
    font-size: 0.9rem;
    font-weight: 500;
    color: var(--gray-700);
    cursor: pointer;
}

.selection-buttons {
    display: none;
    gap: 0.5rem;
    margin-bottom: 1rem;
}

.selection-buttons.visible {
    display: flex;
}

.btn-outline {
    padding: 0.5rem 1rem;
    font-size: 0.8rem;
    font-weight: 500;
    border: 1px solid var(--gray-300);
    border-radius: var(--radius-sm);
    background: white;
    color: var(--gray-600);
    cursor: pointer;
    transition: var(--transition);
}

.btn-outline:hover {
    background: var(--gray-50);
    border-color: var(--gray-400);
    color: var(--gray-800);
}

.columns-grid {
    display: none;
    grid-template-columns: repeat(auto-fill, minmax(180px, 1fr));
    gap: 0.5rem;
}

.columns-grid.visible {
    display: grid;
}

.columns-grid.readonly {
    opacity: 0.6;
    pointer-events: none;
}

.columns-grid.readonly .column-chip {
    background: var(--gray-100);
    border-color: var(--gray-300);
}

.column-chip {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.6rem 0.75rem;
    background: var(--gray-50);
    border: 1px solid var(--gray-200);
    border-radius: var(--radius-sm);
    transition: var(--transition);
    cursor: pointer;
}

.column-chip:hover {
    background: var(--gray-100);
    border-color: var(--gray-300);
}

.column-chip input[type="checkbox"] {
    width: 16px;
    height: 16px;
    accent-color: var(--primary);
    cursor: pointer;
}

.column-chip label {
    font-size: 0.8rem;
    color: var(--gray-700);
    cursor: pointer;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

/* Primary button */
.btn-primary {
    width: 100%;
    padding: 1rem 2rem;
    background: linear-gradient(135deg, #010451 0%, var(--primary) 100%);
    color: white;
    border: none;
    border-radius: var(--radius-md);
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    box-shadow: 0 4px 14px rgba(19, 33, 144, 0.4);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(19, 33, 144, 0.5);
}

.btn-primary:active {
    transform: translateY(0);
}

.btn-primary:disabled {
    background: var(--gray-300);
    cursor: not-allowed;
    box-shadow: none;
    transform: none;
}

.btn-primary svg {
    width: 20px;
    height: 20px;
}

.btn-success {
    background: linear-gradient(135deg, var(--success) 0%, #059669 100%);
    box-shadow: 0 4px 14px rgba(16, 185, 129, 0.4);
}

.btn-success:hover {
    box-shadow: 0 6px 20px rgba(16, 185, 129, 0.5);
}

.btn-secondary {
    width: 100%;
    padding: 1rem 2rem;
    background: white;
    color: var(--gray-700);
    border: 2px solid var(--gray-300);
    border-radius: var(--radius-md);
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    margin-top: 1rem;
}

.btn-secondary:hover {
    background: var(--gray-50);
    border-color: var(--gray-400);
    color: var(--gray-800);
}

.btn-secondary svg {
    width: 20px;
    height: 20px;
}

/* Loading state */
.loading-overlay {
    display: none;
    position: fixed;
    inset: 0;
    background: rgba(255, 255, 255, 0.9);
    backdrop-filter: blur(4px);
    z-index: 1000;
    align-items: center;
    justify-content: center;
    flex-direction: column;
    gap: 1.5rem;
}

.loading-overlay.visible {
    display: flex;
}

.spinner {
    width: 48px;
    height: 48px;
    border: 4px solid var(--gray-200);
    border-top-color: var(--primary);
    border-radius: 50%;
    animation: spin 1s linear infinite;
}

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

.loading-text {
    font-size: 1rem;
    color: var(--gray-600);
    font-weight: 500;
}

/* Results section */
.results-section {
    display: none;
}

.results-section.visible {
    display: block;
}

.success-banner {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    padding: 1rem 1.25rem;
    background: var(--success-light);
    border: 1px solid var(--success);
    border-radius: var(--radius-md);
    margin-bottom: 1.5rem;
}

.success-banner svg {
    width: 24px;
    height: 24px;
    color: var(--success);
    flex-shrink: 0;
}

.success-banner span {
    font-weight: 500;
    color: var(--gray-800);
}

.low-match-warning {
    display: flex;
    align-items: flex-start;
    gap: 0.75rem;
    padding: 1rem 1.25rem;
    background: var(--warning-light);
    border: 1px solid var(--warning);
    border-radius: var(--radius-md);
    margin-bottom: 1.5rem;
    margin-top: 1rem;
}

.low-match-warning svg {
    width: 24px;
    height: 24px;
    color: var(--warning);
    flex-shrink: 0;
}

.low-match-warning strong {
    display: block;
    font-size: 0.95rem;
    color: var(--gray-900);
    margin-bottom: 0.25rem;
}

.low-match-warning p {
    font-size: 0.85rem;
    color: var(--gray-700);
    line-height: 1.5;
    margin: 0;
}

.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
    gap: 1rem;
    margin-bottom: 2rem;
}

.stat-card {
    background: var(--gray-50);
    border: 1px solid var(--gray-200);
    border-radius: var(--radius-md);
    padding: 1.25rem;
    text-align: center;
    transition: var(--transition);
}

.stat-card:hover {
    border-color: var(--gray-300);
    transform: translateY(-2px);
}

.stat-value {
    font-size: 2rem;
    font-weight: 700;
    color: var(--gray-900);
    line-height: 1.2;
}

.stat-label {
    font-size: 0.75rem;
    color: var(--gray-500);
    text-transform: uppercase;
    letter-spacing: 0.05em;
    margin-top: 0.25rem;
}

.stat-card.warning {
    border-color: var(--error);
    background: var(--error-light);
}

.stat-card.warning .stat-value {
    color: var(--error);
}

/* Preview table */
.preview-section {
    margin-bottom: 1.5rem;
}

.preview-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: 1rem;
}

.preview-title {
    font-weight: 600;
    color: var(--gray-700);
}

.preview-badge {
    font-size: 0.75rem;
    color: var(--gray-500);
    background: var(--gray-100);
    padding: 0.25rem 0.75rem;
    border-radius: 9999px;
}

.table-wrapper {
    overflow-x: auto;
    border: 1px solid var(--gray-200);
    border-radius: var(--radius-md);
}

.preview-table {
    width: 100%;
    border-collapse: collapse;
    font-size: 0.8rem;
}

.preview-table th,
.preview-table td {
    padding: 0.75rem 1rem;
    text-align: left;
    border-bottom: 1px solid var(--gray-200);
    white-space: nowrap;
    max-width: 200px;
    overflow: hidden;
    text-overflow: ellipsis;
}

.preview-table th {
    background: var(--gray-50);
    font-weight: 600;
    color: var(--gray-600);
    font-size: 0.7rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    position: sticky;
    top: 0;
}

.preview-table tr:last-child td {
    border-bottom: none;
}

.preview-table tr:hover td {
    background: var(--gray-50);
}

.status-badge {
    display: inline-flex;
    align-items: center;
    padding: 0.25rem 0.5rem;
    border-radius: 9999px;
    font-size: 0.7rem;
    font-weight: 600;
}

.status-badge.ok {
    background: var(--success-light);
    color: var(--success);
}

.status-badge.partial {
    background: var(--warning-light);
    color: var(--warning);
}

.status-badge.error {
    background: var(--error-light);
    color: var(--error);
}

/* Footer */
.footer {
    margin-top: 2rem;
    padding: 1rem 1.25rem;
    background: var(--warning-light);
    border: 1px solid var(--warning);
    border-radius: var(--radius-md);
    display: flex;
    align-items: flex-start;
    gap: 0.75rem;
}

.footer svg {
    width: 20px;
    height: 20px;
    color: var(--warning);
    flex-shrink: 0;
    margin-top: 0.1rem;
}

.footer p {
    font-size: 0.85rem;
    color: var(--gray-700);
    line-height: 1.5;
}

/* Hidden state */
.hidden {
    display: none;
}

/* Ensure hidden has higher specificity for common elements */
.step.hidden,
.file-upload.hidden,
.select-group.hidden,
.columns-grid.hidden,
.selection-buttons.hidden {
    display: none;
}

/* Responsive */
@media (max-width: 640px) {
    .app-container {
        padding: 1rem;
    }

    .header h1 {
        font-size: 1.5rem;
    }

    .step {
        padding: 1.25rem;
    }

    .file-grid {
        grid-template-columns: 1fr;
    }

    .stats-grid {
        grid-template-columns: repeat(2, 1fr);
    }
}