/* ==========================================================================
   Regression Analysis — Web App Styles
   ========================================================================== */

/* --- Reset & Base ------------------------------------------------------ */
*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

:root {
    --color-bg: #f8f9fa;
    --color-surface: #ffffff;
    --color-border: #dee2e6;
    --color-primary: #1f77b4;
    --color-primary-hover: #166094;
    --color-primary-bg: #e8f0fe;
    --color-success: #28a745;
    --color-warning: #ffc107;
    --color-danger: #dc3545;
    --color-text: #212529;
    --color-text-secondary: #6c757d;
    --color-text-muted: #adb5bd;
    --color-green-bg: #e6f4ea;
    --color-yellow-bg: #fef7e0;
    --color-red-bg: #fce8e6;
    --radius: 8px;
    --radius-sm: 4px;
    --shadow: 0 1px 3px rgba(0, 0, 0, 0.08), 0 1px 2px rgba(0, 0, 0, 0.06);
    --shadow-lg: 0 4px 6px rgba(0, 0, 0, 0.07), 0 10px 15px rgba(0, 0, 0, 0.05);
    --transition: 0.2s ease;
    --font-mono: 'SF Mono', 'Fira Code', 'Consolas', monospace;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto,
                 'Helvetica Neue', Arial, sans-serif;
    font-size: 14px;
    line-height: 1.6;
    color: var(--color-text);
    background: var(--color-bg);
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

/* --- Header ------------------------------------------------------------ */
.app-header {
    background: var(--color-surface);
    border-bottom: 1px solid var(--color-border);
    padding: 0.75rem 2rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
    box-shadow: var(--shadow);
    position: sticky;
    top: 0;
    z-index: 100;
}

.header-left {
    display: flex;
    align-items: baseline;
    gap: 0.75rem;
}

.app-title {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--color-primary);
    letter-spacing: -0.02em;
}

.app-version {
    font-size: 0.75rem;
    color: var(--color-text-muted);
    background: var(--color-bg);
    padding: 0.15rem 0.5rem;
    border-radius: 10px;
}

.header-right {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.github-link {
    color: var(--color-text-secondary);
    transition: color var(--transition);
}
.github-link:hover {
    color: var(--color-text);
}

.status-badge {
    font-size: 0.75rem;
    padding: 0.25rem 0.75rem;
    border-radius: 10px;
    font-weight: 500;
}
.status-badge.loading {
    background: var(--color-yellow-bg);
    color: #856404;
}
.status-badge.ready {
    background: var(--color-green-bg);
    color: #155724;
}
.status-badge.error {
    background: var(--color-red-bg);
    color: #721c24;
}

/* --- Tabs Navigation --------------------------------------------------- */
.tab-nav {
    display: flex;
    background: var(--color-surface);
    border-bottom: 2px solid var(--color-border);
    padding: 0 2rem;
    overflow-x: auto;
}

.tab-btn {
    padding: 0.75rem 1.5rem;
    border: none;
    background: none;
    font-size: 0.9rem;
    font-weight: 500;
    color: var(--color-text-secondary);
    cursor: pointer;
    border-bottom: 3px solid transparent;
    margin-bottom: -2px;
    transition: all var(--transition);
    white-space: nowrap;
}
.tab-btn:hover {
    color: var(--color-primary);
    background: var(--color-primary-bg);
}
.tab-btn.active {
    color: var(--color-primary);
    border-bottom-color: var(--color-primary);
    font-weight: 600;
}
.tab-btn:disabled {
    opacity: 0.4;
    cursor: not-allowed;
}
.tab-btn:disabled:hover {
    color: var(--color-text-secondary);
    background: none;
}

/* --- Tab Content ------------------------------------------------------- */
.tab-content {
    display: none;
    padding: 2rem;
}
.tab-content.active {
    display: block;
}
.tab-panel {
    max-width: 1100px;
    margin: 0 auto;
}

.tab-panel h2 {
    font-size: 1.4rem;
    margin-bottom: 0.25rem;
    color: var(--color-text);
}
.tab-panel h3 {
    font-size: 1.1rem;
    margin: 1.5rem 0 0.5rem 0;
    color: var(--color-text);
}
.tab-panel h4 {
    font-size: 0.95rem;
    margin-bottom: 0.5rem;
    color: var(--color-text);
}

.panel-desc {
    color: var(--color-text-secondary);
    margin-bottom: 1.25rem;
    font-size: 0.9rem;
}

/* --- Upload Area ------------------------------------------------------- */
.upload-area {
    border: 2px dashed var(--color-border);
    border-radius: var(--radius);
    padding: 3rem 2rem;
    text-align: center;
    cursor: pointer;
    transition: all var(--transition);
    background: var(--color-surface);
}
.upload-area:hover, .upload-area.drag-over {
    border-color: var(--color-primary);
    background: var(--color-primary-bg);
}
.upload-area.drag-over {
    border-style: solid;
    box-shadow: 0 0 0 3px rgba(31, 119, 180, 0.15);
}

.upload-icon {
    color: var(--color-text-muted);
    margin-bottom: 1rem;
}

.upload-text {
    font-size: 1rem;
    color: var(--color-text);
    margin-bottom: 0.5rem;
}
.upload-link {
    color: var(--color-primary);
    text-decoration: underline;
    font-weight: 500;
}
.upload-hint {
    font-size: 0.8rem;
    color: var(--color-text-muted);
}

/* Upload Progress & File Info */
.upload-progress {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    padding: 1rem;
    color: var(--color-text-secondary);
}
.upload-progress.hidden {
    display: none;
}

.file-info {
    display: flex;
    align-items: center;
    gap: 1rem;
    padding: 0.75rem 1rem;
    background: var(--color-green-bg);
    border-radius: var(--radius);
    margin-top: 1rem;
}
.file-info.hidden {
    display: none;
}
.file-info span:first-child {
    font-weight: 600;
    color: #155724;
}
.file-info span:nth-child(2) {
    font-size: 0.85rem;
    color: var(--color-text-secondary);
}

/* Spinner */
.spinner {
    width: 20px;
    height: 20px;
    border: 3px solid var(--color-border);
    border-top-color: var(--color-primary);
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
}
@keyframes spin {
    to { transform: rotate(360deg); }
}

/* --- Buttons ----------------------------------------------------------- */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 0.5rem 1.25rem;
    border: 1px solid transparent;
    border-radius: var(--radius-sm);
    font-size: 0.9rem;
    font-weight: 500;
    cursor: pointer;
    transition: all var(--transition);
    gap: 0.5rem;
    line-height: 1.4;
}
.btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}
.btn-primary {
    background: var(--color-primary);
    color: white;
    border-color: var(--color-primary);
}
.btn-primary:hover:not(:disabled) {
    background: var(--color-primary-hover);
}
.btn-outline {
    background: white;
    color: var(--color-text-secondary);
    border-color: var(--color-border);
}
.btn-outline:hover:not(:disabled) {
    color: var(--color-danger);
    border-color: var(--color-danger);
}
.btn-sm {
    padding: 0.25rem 0.75rem;
    font-size: 0.8rem;
}
.btn-lg {
    padding: 0.75rem 2rem;
    font-size: 1rem;
}

/* --- Forms ------------------------------------------------------------- */
.form-row {
    margin-bottom: 1rem;
}
.form-row-options {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
    gap: 1rem;
}
.form-group label {
    display: block;
    font-weight: 600;
    font-size: 0.85rem;
    margin-bottom: 0.35rem;
    color: var(--color-text-secondary);
}
.form-group.full-width {
    grid-column: 1 / -1;
}
.form-select {
    width: 100%;
    padding: 0.5rem 0.75rem;
    border: 1px solid var(--color-border);
    border-radius: var(--radius-sm);
    font-size: 0.9rem;
    background: var(--color-surface);
    color: var(--color-text);
    cursor: pointer;
    transition: border-color var(--transition);
}
.form-select:focus {
    outline: none;
    border-color: var(--color-primary);
    box-shadow: 0 0 0 2px rgba(31, 119, 180, 0.15);
}
.form-select-sm {
    padding: 0.35rem 0.5rem;
    font-size: 0.85rem;
}

.checkbox-list {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
    gap: 0.35rem;
    padding: 0.75rem;
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius-sm);
    max-height: 250px;
    overflow-y: auto;
}
.checkbox-list label {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.35rem 0.5rem;
    border-radius: var(--radius-sm);
    font-size: 0.85rem;
    cursor: pointer;
    transition: background var(--transition);
}
.checkbox-list label:hover {
    background: var(--color-primary-bg);
}
.checkbox-list input[type="checkbox"] {
    width: 16px;
    height: 16px;
    accent-color: var(--color-primary);
    cursor: pointer;
}
.checkbox-list .var-numeric {
    color: var(--color-primary);
}
.checkbox-list .var-categorical {
    color: var(--color-success);
}
.checkbox-list .var-id {
    color: var(--color-text-muted);
}

.empty-hint {
    color: var(--color-text-muted);
    font-size: 0.85rem;
    padding: 1rem;
    text-align: center;
    grid-column: 1 / -1;
}

/* --- Data Tables ------------------------------------------------------- */
.data-table-wrapper {
    overflow-x: auto;
    border: 1px solid var(--color-border);
    border-radius: var(--radius);
    background: var(--color-surface);
    margin-bottom: 1rem;
}

.data-table {
    width: 100%;
    border-collapse: collapse;
    font-size: 0.85rem;
}

.data-table th {
    background: #f1f3f5;
    padding: 0.6rem 0.75rem;
    text-align: left;
    font-weight: 600;
    color: var(--color-text-secondary);
    border-bottom: 2px solid var(--color-border);
    white-space: nowrap;
    position: sticky;
    top: 0;
}

.data-table td {
    padding: 0.45rem 0.75rem;
    border-bottom: 1px solid var(--color-border);
    white-space: nowrap;
}

.data-table tbody tr:hover {
    background: var(--color-primary-bg);
}

.data-table td.numeric {
    font-family: var(--font-mono);
    text-align: right;
}

.data-table td.p-significant {
    background: var(--color-green-bg);
    font-weight: 600;
}
.data-table td.p-marginal {
    background: var(--color-yellow-bg);
}

/* --- Stats Grid -------------------------------------------------------- */
.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(150px, 1fr));
    gap: 0.75rem;
    margin-bottom: 1.5rem;
}

.stat-card {
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius);
    padding: 0.75rem 1rem;
    text-align: center;
}
.stat-card .stat-value {
    font-size: 1.3rem;
    font-weight: 700;
    color: var(--color-primary);
    font-family: var(--font-mono);
}
.stat-card .stat-label {
    font-size: 0.75rem;
    color: var(--color-text-muted);
    margin-top: 0.15rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

/* --- Charts ------------------------------------------------------------ */
.chart-container {
    width: 100%;
    min-height: 350px;
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius);
    margin-bottom: 1.5rem;
}

/* --- Summary Text ------------------------------------------------------ */
.summary-text {
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius);
    padding: 1.25rem;
    line-height: 1.8;
    font-size: 0.9rem;
}

/* --- Diagnostics Grid -------------------------------------------------- */
.diag-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1.5rem;
}

@media (max-width: 800px) {
    .diag-grid {
        grid-template-columns: 1fr;
    }
}

.diag-card {
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius);
    padding: 1rem;
}

.diag-card h4 {
    margin-bottom: 0.5rem;
}

/* --- Gallery Grid ------------------------------------------------------ */
.gallery-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 1rem;
}

.gallery-card {
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius);
    padding: 1.25rem;
    transition: box-shadow var(--transition);
    cursor: pointer;
}
.gallery-card:hover {
    box-shadow: var(--shadow-lg);
    border-color: var(--color-primary);
}

.gallery-card .card-title {
    font-size: 1rem;
    font-weight: 600;
    color: var(--color-text);
    margin-bottom: 0.25rem;
}
.gallery-card .card-persona {
    font-size: 0.8rem;
    color: var(--color-text-muted);
    margin-bottom: 0.5rem;
}
.gallery-card .card-desc {
    font-size: 0.85rem;
    color: var(--color-text-secondary);
    margin-bottom: 0.75rem;
    line-height: 1.5;
}
.gallery-card .card-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 0.35rem;
    margin-bottom: 0.75rem;
}
.gallery-card .tag {
    font-size: 0.72rem;
    padding: 0.15rem 0.5rem;
    background: var(--color-primary-bg);
    color: var(--color-primary);
    border-radius: 10px;
    font-weight: 500;
}
.gallery-card .card-meta {
    font-size: 0.78rem;
    color: var(--color-text-muted);
    display: flex;
    justify-content: space-between;
}

/* --- Export Options ---------------------------------------------------- */
.export-options {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
    gap: 1rem;
}

.export-card {
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius);
    padding: 1.5rem;
    text-align: center;
}
.export-card h4 {
    margin-bottom: 0.5rem;
}
.export-card p {
    font-size: 0.85rem;
    color: var(--color-text-secondary);
    margin-bottom: 1rem;
}

/* --- Error Box --------------------------------------------------------- */
.error-box {
    background: var(--color-red-bg);
    color: #721c24;
    border: 1px solid #f5c6cb;
    border-radius: var(--radius);
    padding: 0.75rem 1rem;
    margin-bottom: 1rem;
    font-size: 0.9rem;
}
.error-box.hidden {
    display: none;
}

/* --- Empty State ------------------------------------------------------- */
.empty-state {
    text-align: center;
    padding: 3rem 1rem;
    color: var(--color-text-muted);
}

/* --- Section Divider --------------------------------------------------- */
.section-divider {
    border: none;
    border-top: 1px solid var(--color-border);
    margin: 2rem 0;
}

/* --- Variable Item (checkbox + transform) ------------------------------ */
.var-item {
    display: flex;
    align-items: center;
    gap: 0.3rem;
    padding: 0.15rem 0.3rem;
}
.var-item label {
    flex: 1;
    display: flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.25rem 0.4rem;
    border-radius: var(--radius-sm);
    font-size: 0.85rem;
    cursor: pointer;
    transition: background var(--transition);
}
.var-item label:hover {
    background: var(--color-primary-bg);
}
.var-item input[type="checkbox"] {
    width: 16px;
    height: 16px;
    accent-color: var(--color-primary);
    cursor: pointer;
    flex-shrink: 0;
}
.var-transform {
    width: 90px;
    font-size: 0.72rem !important;
    padding: 0.2rem 0.3rem !important;
    flex-shrink: 0;
}

/* --- Interaction Controls ----------------------------------------------- */
.interaction-controls {
    margin-top: 0.3rem;
}
.interaction-selects {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    flex-wrap: wrap;
}
.interaction-times {
    font-weight: 700;
    color: var(--color-text-secondary);
    font-size: 1.1rem;
}
.interaction-list {
    display: flex;
    flex-wrap: wrap;
    gap: 0.4rem;
    margin-top: 0.5rem;
    min-height: 0;
}
.interaction-tag {
    display: inline-flex;
    align-items: center;
    gap: 0.4rem;
    background: var(--color-primary-bg);
    border: 1px solid var(--color-primary);
    border-radius: var(--radius-sm);
    padding: 0.2rem 0.5rem;
    font-size: 0.82rem;
    color: var(--color-primary);
}
.btn-interaction-remove {
    background: none;
    border: none;
    color: var(--color-danger);
    font-size: 1rem;
    cursor: pointer;
    padding: 0 0.15rem;
    line-height: 1;
}
.btn-interaction-remove:hover {
    color: #a71d2a;
}

/* --- Comparison Section ------------------------------------------------- */
.compare-section {
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius);
    padding: 1.25rem;
    margin-bottom: 1rem;
}
.compare-controls {
    display: flex;
    align-items: center;
    gap: 0.75rem;
    margin-bottom: 0.75rem;
    flex-wrap: wrap;
}
.compare-model-list {
    display: flex;
    flex-wrap: wrap;
    gap: 0.4rem;
    margin-bottom: 0.75rem;
}
.compare-model-item {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    background: var(--color-green-bg);
    border: 1px solid #c3e6cb;
    border-radius: var(--radius-sm);
    padding: 0.25rem 0.6rem;
    font-size: 0.82rem;
}
.compare-model-item span {
    color: #155724;
}
.compare-actions {
    display: flex;
    gap: 0.5rem;
}

/* --- Form Input --------------------------------------------------------- */
.form-input {
    padding: 0.4rem 0.6rem;
    border: 1px solid var(--color-border);
    border-radius: var(--radius-sm);
    font-size: 0.85rem;
    background: var(--color-surface);
    color: var(--color-text);
    transition: border-color var(--transition);
}
.form-input:focus {
    outline: none;
    border-color: var(--color-primary);
    box-shadow: 0 0 0 2px rgba(31, 119, 180, 0.15);
}

/* --- Visualization Grid ------------------------------------------------- */
.viz-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(420px, 1fr));
    gap: 1rem;
}
.viz-card {
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius);
    padding: 0.5rem;
}

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

/* --- Footer ------------------------------------------------------------ */
.app-footer {
    margin-top: auto;
    padding: 1rem 2rem;
    text-align: center;
    font-size: 0.8rem;
    color: var(--color-text-muted);
    border-top: 1px solid var(--color-border);
    background: var(--color-surface);
}
.app-footer a {
    color: var(--color-primary);
    text-decoration: none;
}
.app-footer a:hover {
    text-decoration: underline;
}

/* --- Responsive -------------------------------------------------------- */
@media (max-width: 768px) {
    .app-header {
        padding: 0.5rem 1rem;
    }
    .tab-nav {
        padding: 0 1rem;
    }
    .tab-btn {
        padding: 0.5rem 0.75rem;
        font-size: 0.8rem;
    }
    .tab-content {
        padding: 1rem;
    }
    .form-row-options {
        grid-template-columns: 1fr;
    }
    .stats-grid {
        grid-template-columns: repeat(auto-fill, minmax(120px, 1fr));
    }
    .gallery-grid {
        grid-template-columns: 1fr;
    }
}