/* ═══════════════════════════════════════════════════════════
   HealthStat — Sağlık Bilimleri İstatistik Analiz Uygulaması
   Design System & Global Styles
   ═══════════════════════════════════════════════════════════ */

@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700;800&family=JetBrains+Mono:wght@400;500;600&display=swap');

/* ─── CSS Variables ─── */
:root {
    /* Primary - Medical Teal */
    --primary-50: #e6fcf5;
    --primary-100: #b2f5ea;
    --primary-200: #81e6d9;
    --primary-300: #4fd1c5;
    --primary-400: #38b2ac;
    --primary-500: #2c9f94;
    --primary-600: #1d8a80;
    --primary-700: #167a72;
    --primary-800: #0f5f59;
    --primary-900: #0a4741;

    /* Accent - Deep Blue */
    --accent-50: #ebf4ff;
    --accent-100: #c3dafe;
    --accent-200: #a3bffa;
    --accent-300: #7f9cf5;
    --accent-400: #667eea;
    --accent-500: #5a67d8;
    --accent-600: #4c51bf;
    --accent-700: #434190;
    --accent-800: #3c366b;
    --accent-900: #2d2b55;

    /* Success */
    --success-400: #48bb78;
    --success-500: #38a169;
    --success-600: #2f855a;

    /* Warning */
    --warning-400: #ecc94b;
    --warning-500: #d69e2e;

    /* Danger */
    --danger-400: #fc8181;
    --danger-500: #f56565;
    --danger-600: #e53e3e;

    /* Neutrals */
    --gray-50: #f7fafc;
    --gray-100: #edf2f7;
    --gray-200: #e2e8f0;
    --gray-300: #cbd5e0;
    --gray-400: #a0aec0;
    --gray-500: #718096;
    --gray-600: #4a5568;
    --gray-700: #2d3748;
    --gray-800: #1a202c;
    --gray-900: #0d1117;

    /* Dark Mode Colors */
    --bg-primary: #0d1117;
    --bg-secondary: #161b22;
    --bg-tertiary: #1c2333;
    --bg-card: #21262d;
    --bg-card-hover: #282e38;
    --bg-input: #1a1f2b;
    --border-color: #30363d;
    --border-light: #21262d;
    --text-primary: #e6edf3;
    --text-secondary: #8b949e;
    --text-tertiary: #6e7681;
    --text-link: #58a6ff;

    /* Glass Effect */
    --glass-bg: rgba(22, 27, 34, 0.85);
    --glass-border: rgba(48, 54, 61, 0.6);
    --glass-shadow: 0 8px 32px rgba(0, 0, 0, 0.3);

    /* Spacing */
    --space-xs: 4px;
    --space-sm: 8px;
    --space-md: 16px;
    --space-lg: 24px;
    --space-xl: 32px;
    --space-2xl: 48px;
    --space-3xl: 64px;

    /* Border Radius */
    --radius-sm: 6px;
    --radius-md: 10px;
    --radius-lg: 16px;
    --radius-xl: 20px;
    --radius-full: 50%;

    /* Transitions */
    --transition-fast: 0.15s ease;
    --transition-normal: 0.25s ease;
    --transition-slow: 0.4s ease;

    /* Sidebar */
    --sidebar-width: 280px;
    --sidebar-collapsed: 72px;
}

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

html {
    font-size: 15px;
    scroll-behavior: smooth;
}

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

/* ─── Scrollbar ─── */
::-webkit-scrollbar {
    width: 8px;
    height: 8px;
}
::-webkit-scrollbar-track {
    background: var(--bg-secondary);
}
::-webkit-scrollbar-thumb {
    background: var(--gray-600);
    border-radius: 4px;
}
::-webkit-scrollbar-thumb:hover {
    background: var(--gray-500);
}

/* ─── Layout ─── */
.app-container {
    display: flex;
    height: 100vh;
    width: 100%;
}

/* ─── Sidebar ─── */
.sidebar {
    width: var(--sidebar-width);
    min-width: var(--sidebar-width);
    height: 100vh;
    background: var(--bg-secondary);
    border-right: 1px solid var(--border-color);
    display: flex;
    flex-direction: column;
    transition: width var(--transition-normal), min-width var(--transition-normal);
    z-index: 100;
    overflow: hidden;
}

.sidebar-header {
    padding: var(--space-lg);
    border-bottom: 1px solid var(--border-color);
    display: flex;
    align-items: center;
    gap: var(--space-md);
}

.sidebar-logo {
    width: 42px;
    height: 42px;
    background: linear-gradient(135deg, var(--primary-400), var(--accent-400));
    border-radius: var(--radius-md);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.4rem;
    flex-shrink: 0;
    box-shadow: 0 4px 15px rgba(56, 178, 172, 0.3);
}

.sidebar-brand {
    display: flex;
    flex-direction: column;
}

.sidebar-brand h1 {
    font-size: 1.15rem;
    font-weight: 700;
    background: linear-gradient(135deg, var(--primary-300), var(--accent-300));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    letter-spacing: -0.3px;
}

.sidebar-brand span {
    font-size: 0.7rem;
    color: var(--text-tertiary);
    font-weight: 400;
    letter-spacing: 0.5px;
    text-transform: uppercase;
}

.sidebar-nav {
    flex: 1;
    overflow-y: auto;
    padding: var(--space-md) var(--space-sm);
}

.nav-section {
    margin-bottom: var(--space-lg);
}

.nav-section-title {
    font-size: 0.65rem;
    font-weight: 600;
    color: var(--text-tertiary);
    text-transform: uppercase;
    letter-spacing: 1.2px;
    padding: var(--space-sm) var(--space-md);
    margin-bottom: var(--space-xs);
}

.nav-item {
    display: flex;
    align-items: center;
    gap: var(--space-md);
    padding: 10px var(--space-md);
    border-radius: var(--radius-md);
    color: var(--text-secondary);
    cursor: pointer;
    transition: all var(--transition-fast);
    font-size: 0.87rem;
    font-weight: 500;
    position: relative;
    margin-bottom: 2px;
    user-select: none;
}

.nav-item:hover {
    background: var(--bg-tertiary);
    color: var(--text-primary);
}

.nav-item.active {
    background: linear-gradient(135deg, rgba(56, 178, 172, 0.15), rgba(102, 126, 234, 0.1));
    color: var(--primary-300);
    border: 1px solid rgba(56, 178, 172, 0.25);
}

.nav-item.active::before {
    content: '';
    position: absolute;
    left: 0;
    top: 50%;
    transform: translateY(-50%);
    width: 3px;
    height: 60%;
    background: linear-gradient(180deg, var(--primary-400), var(--accent-400));
    border-radius: 0 4px 4px 0;
}

.nav-icon {
    font-size: 1.15rem;
    width: 28px;
    text-align: center;
    flex-shrink: 0;
}

.nav-badge {
    margin-left: auto;
    background: var(--primary-700);
    color: var(--primary-200);
    font-size: 0.6rem;
    padding: 2px 8px;
    border-radius: 10px;
    font-weight: 600;
}

/* Status Bar */
.sidebar-footer {
    padding: var(--space-md) var(--space-lg);
    border-top: 1px solid var(--border-color);
    background: var(--bg-tertiary);
}

.data-status {
    display: flex;
    align-items: center;
    gap: var(--space-sm);
    font-size: 0.75rem;
    color: var(--text-tertiary);
}

.status-dot {
    width: 8px;
    height: 8px;
    border-radius: var(--radius-full);
    background: var(--gray-600);
    flex-shrink: 0;
}

.status-dot.active {
    background: var(--success-400);
    box-shadow: 0 0 8px rgba(72, 187, 120, 0.5);
    animation: pulse-dot 2s infinite;
}

@keyframes pulse-dot {
    0%, 100% { opacity: 1; }
    50% { opacity: 0.5; }
}

/* ─── Main Content ─── */
.main-content {
    flex: 1;
    display: flex;
    flex-direction: column;
    overflow: hidden;
}

.content-header {
    padding: var(--space-lg) var(--space-xl);
    border-bottom: 1px solid var(--border-color);
    background: var(--bg-secondary);
    display: flex;
    align-items: center;
    justify-content: space-between;
    min-height: 70px;
}

.content-header h2 {
    font-size: 1.3rem;
    font-weight: 700;
    display: flex;
    align-items: center;
    gap: var(--space-md);
}

.content-header h2 .header-icon {
    font-size: 1.5rem;
}

.header-actions {
    display: flex;
    gap: var(--space-sm);
}

.content-body {
    flex: 1;
    overflow-y: auto;
    padding: var(--space-xl);
}

/* ─── Section/Page Visibility ─── */
.page-section {
    display: none;
    animation: fadeSlideIn 0.35s ease;
}

.page-section.active {
    display: block;
}

@keyframes fadeSlideIn {
    from {
        opacity: 0;
        transform: translateY(12px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

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

.card:hover {
    border-color: rgba(56, 178, 172, 0.3);
    box-shadow: 0 4px 20px rgba(0, 0, 0, 0.15);
}

.card-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: var(--space-lg);
    padding-bottom: var(--space-md);
    border-bottom: 1px solid var(--border-color);
}

.card-title {
    font-size: 1.05rem;
    font-weight: 600;
    display: flex;
    align-items: center;
    gap: var(--space-sm);
}

.card-title .card-icon {
    color: var(--primary-400);
}

/* ─── Welcome Section ─── */
.welcome-hero {
    text-align: center;
    padding: var(--space-3xl) var(--space-xl);
}

.welcome-hero h2 {
    font-size: 2rem;
    font-weight: 800;
    margin-bottom: var(--space-md);
    background: linear-gradient(135deg, var(--primary-300), var(--accent-300));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.welcome-hero p {
    color: var(--text-secondary);
    font-size: 1.05rem;
    max-width: 600px;
    margin: 0 auto var(--space-xl);
    line-height: 1.7;
}

.welcome-cards {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
    gap: var(--space-lg);
    max-width: 900px;
    margin: 0 auto;
}

.welcome-card {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: var(--space-xl) var(--space-lg);
    text-align: center;
    cursor: pointer;
    transition: all var(--transition-normal);
    position: relative;
    overflow: hidden;
}

.welcome-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 3px;
    background: linear-gradient(135deg, var(--primary-400), var(--accent-400));
    opacity: 0;
    transition: opacity var(--transition-normal);
}

.welcome-card:hover {
    transform: translateY(-4px);
    border-color: rgba(56, 178, 172, 0.4);
    box-shadow: 0 12px 40px rgba(0, 0, 0, 0.2);
}

.welcome-card:hover::before {
    opacity: 1;
}

.welcome-card-icon {
    font-size: 2.5rem;
    margin-bottom: var(--space-md);
    display: block;
}

.welcome-card h3 {
    font-size: 0.95rem;
    font-weight: 600;
    margin-bottom: var(--space-sm);
    color: var(--text-primary);
}

.welcome-card p {
    font-size: 0.78rem;
    color: var(--text-tertiary);
    line-height: 1.5;
}

/* ─── Buttons ─── */
.btn {
    display: inline-flex;
    align-items: center;
    gap: var(--space-sm);
    padding: 10px 20px;
    border-radius: var(--radius-md);
    font-family: 'Inter', sans-serif;
    font-size: 0.85rem;
    font-weight: 600;
    cursor: pointer;
    border: none;
    transition: all var(--transition-fast);
    user-select: none;
    white-space: nowrap;
}

.btn-primary {
    background: linear-gradient(135deg, var(--primary-500), var(--primary-600));
    color: white;
    box-shadow: 0 4px 15px rgba(44, 159, 148, 0.3);
}

.btn-primary:hover {
    background: linear-gradient(135deg, var(--primary-400), var(--primary-500));
    box-shadow: 0 6px 20px rgba(44, 159, 148, 0.4);
    transform: translateY(-1px);
}

.btn-secondary {
    background: var(--bg-tertiary);
    color: var(--text-primary);
    border: 1px solid var(--border-color);
}

.btn-secondary:hover {
    background: var(--bg-card-hover);
    border-color: var(--primary-500);
}

.btn-accent {
    background: linear-gradient(135deg, var(--accent-500), var(--accent-600));
    color: white;
    box-shadow: 0 4px 15px rgba(90, 103, 216, 0.3);
}

.btn-accent:hover {
    transform: translateY(-1px);
    box-shadow: 0 6px 20px rgba(90, 103, 216, 0.4);
}

.btn-danger {
    background: var(--danger-600);
    color: white;
}

.btn-sm {
    padding: 6px 14px;
    font-size: 0.78rem;
}

.btn-lg {
    padding: 14px 28px;
    font-size: 0.95rem;
}

.btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
    transform: none !important;
}

/* ─── Form Controls ─── */
.form-group {
    margin-bottom: var(--space-lg);
}

.form-label {
    display: block;
    font-size: 0.82rem;
    font-weight: 600;
    color: var(--text-secondary);
    margin-bottom: var(--space-sm);
}

.form-select, .form-input {
    width: 100%;
    padding: 10px 14px;
    background: var(--bg-input);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    color: var(--text-primary);
    font-family: 'Inter', sans-serif;
    font-size: 0.87rem;
    transition: all var(--transition-fast);
    outline: none;
}

.form-select:focus, .form-input:focus {
    border-color: var(--primary-500);
    box-shadow: 0 0 0 3px rgba(44, 159, 148, 0.15);
}

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

.form-row {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: var(--space-md);
}

.form-row-3 {
    display: grid;
    grid-template-columns: 1fr 1fr 1fr;
    gap: var(--space-md);
}

.form-help {
    font-size: 0.73rem;
    color: var(--text-tertiary);
    margin-top: var(--space-xs);
}

/* ─── Data Table ─── */
.data-table-wrapper {
    overflow: auto;
    max-height: 500px;
    border-radius: var(--radius-md);
    border: 1px solid var(--border-color);
}

.data-table {
    width: 100%;
    border-collapse: collapse;
    font-size: 0.82rem;
}

.data-table thead {
    position: sticky;
    top: 0;
    z-index: 10;
}

.data-table th {
    background: var(--bg-tertiary);
    color: var(--primary-300);
    font-weight: 600;
    text-align: left;
    padding: 10px 14px;
    border-bottom: 2px solid var(--primary-700);
    white-space: nowrap;
    font-size: 0.78rem;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.data-table td {
    padding: 8px 14px;
    border-bottom: 1px solid var(--border-light);
    color: var(--text-secondary);
    white-space: nowrap;
}

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

.data-table tbody tr:nth-child(even) {
    background: rgba(22, 27, 34, 0.5);
}

.data-table tbody tr:nth-child(even):hover {
    background: var(--bg-card-hover);
}

/* ─── Result/Output Tables ─── */
.result-table {
    width: 100%;
    border-collapse: collapse;
    font-size: 0.85rem;
    margin: var(--space-md) 0;
}

.result-table th {
    background: linear-gradient(135deg, rgba(56, 178, 172, 0.15), rgba(102, 126, 234, 0.1));
    color: var(--primary-300);
    padding: 10px 16px;
    text-align: left;
    font-weight: 600;
    border-bottom: 2px solid var(--primary-700);
}

.result-table td {
    padding: 10px 16px;
    border-bottom: 1px solid var(--border-light);
    color: var(--text-primary);
}

.result-table tbody tr:hover {
    background: var(--bg-card-hover);
}

.result-table .significant {
    color: var(--success-400);
    font-weight: 600;
}

.result-table .not-significant {
    color: var(--danger-400);
}

/* ─── File Upload ─── */
.upload-zone {
    border: 2px dashed var(--border-color);
    border-radius: var(--radius-lg);
    padding: var(--space-3xl) var(--space-xl);
    text-align: center;
    cursor: pointer;
    transition: all var(--transition-normal);
    position: relative;
}

.upload-zone:hover, .upload-zone.dragover {
    border-color: var(--primary-400);
    background: rgba(56, 178, 172, 0.05);
}

.upload-zone.dragover {
    transform: scale(1.01);
    box-shadow: 0 0 30px rgba(56, 178, 172, 0.15);
}

.upload-icon {
    font-size: 3.5rem;
    margin-bottom: var(--space-lg);
    display: block;
    opacity: 0.7;
}

.upload-zone h3 {
    font-size: 1.1rem;
    font-weight: 600;
    margin-bottom: var(--space-sm);
    color: var(--text-primary);
}

.upload-zone p {
    font-size: 0.85rem;
    color: var(--text-tertiary);
}

.upload-zone input[type="file"] {
    position: absolute;
    inset: 0;
    opacity: 0;
    cursor: pointer;
}

.upload-formats {
    display: flex;
    gap: var(--space-sm);
    justify-content: center;
    margin-top: var(--space-md);
}

.format-badge {
    padding: 4px 12px;
    border-radius: var(--radius-sm);
    font-size: 0.7rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.format-csv {
    background: rgba(72, 187, 120, 0.15);
    color: var(--success-400);
}

.format-excel {
    background: rgba(102, 126, 234, 0.15);
    color: var(--accent-300);
}

/* ─── Analysis Section Panels ─── */
.analysis-panel {
    display: grid;
    grid-template-columns: 300px 1fr;
    gap: var(--space-lg);
}

.analysis-controls {
    position: sticky;
    top: 0;
    align-self: start;
}

.analysis-results {
    min-width: 0;
}

/* ─── Wizard ─── */
.wizard-container {
    max-width: 700px;
    margin: 0 auto;
}

.wizard-step {
    display: none;
    animation: fadeSlideIn 0.35s ease;
}

.wizard-step.active {
    display: block;
}

.wizard-question {
    font-size: 1.2rem;
    font-weight: 700;
    margin-bottom: var(--space-lg);
    color: var(--text-primary);
    text-align: center;
    line-height: 1.5;
}

.wizard-options {
    display: grid;
    gap: var(--space-md);
}

.wizard-option {
    background: var(--bg-card);
    border: 2px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: var(--space-lg);
    cursor: pointer;
    transition: all var(--transition-normal);
    display: flex;
    align-items: center;
    gap: var(--space-lg);
}

.wizard-option:hover {
    border-color: var(--primary-400);
    background: rgba(56, 178, 172, 0.05);
    transform: translateX(6px);
}

.wizard-option-icon {
    font-size: 2rem;
    flex-shrink: 0;
}

.wizard-option h4 {
    font-size: 0.95rem;
    font-weight: 600;
    margin-bottom: var(--space-xs);
}

.wizard-option p {
    font-size: 0.78rem;
    color: var(--text-tertiary);
    line-height: 1.4;
}

.wizard-result {
    text-align: center;
    padding: var(--space-xl);
}

.wizard-result-icon {
    font-size: 3rem;
    margin-bottom: var(--space-md);
}

.wizard-result h3 {
    font-size: 1.3rem;
    font-weight: 700;
    margin-bottom: var(--space-sm);
    color: var(--primary-300);
}

.wizard-result p {
    color: var(--text-secondary);
    margin-bottom: var(--space-lg);
    line-height: 1.6;
}

.wizard-breadcrumb {
    display: flex;
    align-items: center;
    gap: var(--space-sm);
    justify-content: center;
    margin-bottom: var(--space-xl);
    flex-wrap: wrap;
}

.wizard-breadcrumb span {
    font-size: 0.75rem;
    color: var(--text-tertiary);
    padding: 4px 10px;
    background: var(--bg-card);
    border-radius: var(--radius-sm);
}

.wizard-breadcrumb span.current {
    background: var(--primary-700);
    color: var(--primary-200);
}

.wizard-breadcrumb .sep {
    color: var(--text-tertiary);
    background: none;
    padding: 0;
}

/* ─── Result Cards / APA Format ─── */
.result-box {
    background: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    padding: var(--space-lg);
    margin: var(--space-md) 0;
    font-family: 'JetBrains Mono', monospace;
    font-size: 0.83rem;
    line-height: 1.8;
    color: var(--text-primary);
}

.result-box .label {
    color: var(--text-tertiary);
    font-family: 'Inter', sans-serif;
    font-size: 0.73rem;
    text-transform: uppercase;
    letter-spacing: 0.8px;
    margin-bottom: var(--space-xs);
    display: block;
    font-weight: 600;
}

.result-interpretation {
    background: linear-gradient(135deg, rgba(56, 178, 172, 0.1), rgba(102, 126, 234, 0.05));
    border: 1px solid rgba(56, 178, 172, 0.2);
    border-radius: var(--radius-md);
    padding: var(--space-lg);
    margin-top: var(--space-md);
}

.result-interpretation h4 {
    color: var(--primary-300);
    font-size: 0.9rem;
    margin-bottom: var(--space-sm);
    display: flex;
    align-items: center;
    gap: var(--space-sm);
}

.result-interpretation p {
    color: var(--text-secondary);
    font-size: 0.85rem;
    line-height: 1.7;
}

/* Significance Indicator */
.sig-badge {
    display: inline-flex;
    align-items: center;
    gap: 4px;
    padding: 3px 10px;
    border-radius: var(--radius-sm);
    font-size: 0.72rem;
    font-weight: 700;
}

.sig-badge.significant {
    background: rgba(72, 187, 120, 0.15);
    color: var(--success-400);
}

.sig-badge.not-significant {
    background: rgba(245, 101, 101, 0.15);
    color: var(--danger-400);
}

/* ─── Charts ─── */
.chart-container {
    position: relative;
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: var(--space-lg);
    margin: var(--space-md) 0;
}

.chart-container canvas {
    max-height: 400px;
}

.chart-actions {
    display: flex;
    justify-content: flex-end;
    gap: var(--space-sm);
    margin-top: var(--space-md);
}

/* ─── Notification / Toast ─── */
.toast-container {
    position: fixed;
    top: var(--space-lg);
    right: var(--space-lg);
    z-index: 9999;
    display: flex;
    flex-direction: column;
    gap: var(--space-sm);
}

.toast {
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    padding: var(--space-md) var(--space-lg);
    display: flex;
    align-items: center;
    gap: var(--space-md);
    box-shadow: 0 8px 30px rgba(0, 0, 0, 0.3);
    animation: slideInRight 0.3s ease;
    min-width: 300px;
    font-size: 0.85rem;
}

.toast.success {
    border-left: 4px solid var(--success-400);
}

.toast.error {
    border-left: 4px solid var(--danger-500);
}

.toast.info {
    border-left: 4px solid var(--accent-400);
}

@keyframes slideInRight {
    from {
        transform: translateX(100%);
        opacity: 0;
    }
    to {
        transform: translateX(0);
        opacity: 1;
    }
}

/* ─── Loading Spinner ─── */
.spinner {
    display: inline-block;
    width: 20px;
    height: 20px;
    border: 2px solid var(--border-color);
    border-top-color: var(--primary-400);
    border-radius: 50%;
    animation: spin 0.7s linear infinite;
}

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

.loading-overlay {
    position: absolute;
    inset: 0;
    background: rgba(13, 17, 23, 0.7);
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: var(--radius-lg);
    z-index: 50;
    backdrop-filter: blur(4px);
}

/* ─── Empty State ─── */
.empty-state {
    text-align: center;
    padding: var(--space-3xl) var(--space-xl);
    color: var(--text-tertiary);
}

.empty-state-icon {
    font-size: 3rem;
    margin-bottom: var(--space-lg);
    opacity: 0.5;
}

.empty-state h3 {
    font-size: 1.1rem;
    margin-bottom: var(--space-sm);
    color: var(--text-secondary);
}

.empty-state p {
    font-size: 0.85rem;
    max-width: 400px;
    margin: 0 auto;
}

/* ─── Stats Summary Grid ─── */
.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
    gap: var(--space-md);
    margin-bottom: var(--space-lg);
}

.stat-card {
    background: var(--bg-tertiary);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    padding: var(--space-lg);
    text-align: center;
    transition: all var(--transition-fast);
}

.stat-card:hover {
    border-color: var(--primary-500);
    transform: translateY(-2px);
}

.stat-value {
    font-size: 1.6rem;
    font-weight: 700;
    color: var(--primary-300);
    font-family: 'JetBrains Mono', monospace;
    margin-bottom: 4px;
}

.stat-label {
    font-size: 0.72rem;
    color: var(--text-tertiary);
    text-transform: uppercase;
    letter-spacing: 0.8px;
    font-weight: 600;
}

/* ─── Tabs ─── */
.tab-bar {
    display: flex;
    gap: 2px;
    background: var(--bg-secondary);
    border-radius: var(--radius-md);
    padding: 3px;
    margin-bottom: var(--space-lg);
    border: 1px solid var(--border-color);
    overflow-x: auto;
}

.tab-item {
    padding: 8px 18px;
    border-radius: var(--radius-sm);
    font-size: 0.82rem;
    font-weight: 500;
    color: var(--text-secondary);
    cursor: pointer;
    transition: all var(--transition-fast);
    white-space: nowrap;
    border: none;
    background: transparent;
    font-family: 'Inter', sans-serif;
}

.tab-item:hover {
    color: var(--text-primary);
    background: var(--bg-tertiary);
}

.tab-item.active {
    background: var(--primary-700);
    color: var(--primary-100);
}

/* ─── Responsive ─── */
@media (max-width: 1024px) {
    .analysis-panel {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 768px) {
    .sidebar {
        position: fixed;
        left: -100%;
        z-index: 999;
    }
    .sidebar.open {
        left: 0;
    }
    .form-row {
        grid-template-columns: 1fr;
    }
    .form-row-3 {
        grid-template-columns: 1fr;
    }
    .welcome-cards {
        grid-template-columns: 1fr;
    }
}

/* ─── Variable Type Tags ─── */
.var-tag {
    display: inline-block;
    padding: 2px 8px;
    border-radius: var(--radius-sm);
    font-size: 0.65rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.var-tag.numeric {
    background: rgba(102, 126, 234, 0.15);
    color: var(--accent-300);
}

.var-tag.categorical {
    background: rgba(236, 201, 75, 0.15);
    color: var(--warning-400);
}

/* ─── Progress Bar ─── */
.progress-bar {
    height: 6px;
    background: var(--bg-tertiary);
    border-radius: 3px;
    overflow: hidden;
}

.progress-fill {
    height: 100%;
    background: linear-gradient(90deg, var(--primary-500), var(--accent-400));
    border-radius: 3px;
    transition: width 0.5s ease;
}

/* ─── Dividers ─── */
.divider {
    height: 1px;
    background: var(--border-color);
    margin: var(--space-lg) 0;
}

/* ─── Utility Classes ─── */
.text-center { text-align: center; }
.text-right { text-align: right; }
.text-muted { color: var(--text-tertiary); }
.text-primary-c { color: var(--primary-300); }
.text-success { color: var(--success-400); }
.text-danger { color: var(--danger-400); }
.text-mono { font-family: 'JetBrains Mono', monospace; }
.font-bold { font-weight: 700; }
.mt-md { margin-top: var(--space-md); }
.mt-lg { margin-top: var(--space-lg); }
.mb-md { margin-bottom: var(--space-md); }
.mb-lg { margin-bottom: var(--space-lg); }
.flex { display: flex; }
.flex-center { display: flex; align-items: center; justify-content: center; }
.gap-sm { gap: var(--space-sm); }
.gap-md { gap: var(--space-md); }
.hidden { display: none !important; }