/* ═══════════════════════════════════════════════════════════
   NeuroAge — Brain Age Prediction UI
   Premium dark-mode design with glassmorphism
   ═══════════════════════════════════════════════════════════ */

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

:root {
    --bg-primary: #0a0e1a;
    --bg-secondary: #111827;
    --bg-card: rgba(17, 24, 39, 0.7);
    --bg-card-hover: rgba(30, 41, 59, 0.8);
    --border-color: rgba(99, 102, 241, 0.15);
    --border-glow: rgba(99, 102, 241, 0.3);

    --text-primary: #f1f5f9;
    --text-secondary: #94a3b8;
    --text-muted: #64748b;

    --accent-primary: #6366f1;
    --accent-secondary: #8b5cf6;
    --accent-gradient: linear-gradient(135deg, #6366f1, #8b5cf6, #a78bfa);
    --accent-glow: 0 0 30px rgba(99, 102, 241, 0.3);

    --green: #22c55e;
    --green-soft: rgba(34, 197, 94, 0.15);
    --amber: #f59e0b;
    --amber-soft: rgba(245, 158, 11, 0.15);
    --red: #ef4444;
    --red-soft: rgba(239, 68, 68, 0.15);
    --blue: #3b82f6;
    --blue-soft: rgba(59, 130, 246, 0.15);

    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 20px;
    --radius-xl: 28px;

    --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
    --font-mono: 'JetBrains Mono', 'Fira Code', monospace;

    --transition: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-sans);
    background: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
    overflow-x: hidden;
}

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

a { color: var(--accent-primary); text-decoration: none; }
a:hover { text-decoration: underline; }

.mono { font-family: var(--font-mono); font-size: 0.88em; }

/* ─── Glass Card ─── */
.glass-card {
    background: var(--bg-card);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: 2rem;
    transition: var(--transition);
}
.glass-card:hover {
    border-color: var(--border-glow);
    box-shadow: var(--accent-glow);
}


/* ═══════════════ HERO ═══════════════ */
.hero {
    position: relative;
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
    overflow: hidden;
}

.hero-bg {
    position: absolute;
    inset: 0;
    background:
        radial-gradient(ellipse 60% 50% at 50% 30%, rgba(99, 102, 241, 0.12), transparent),
        radial-gradient(ellipse 40% 30% at 70% 70%, rgba(139, 92, 246, 0.08), transparent),
        radial-gradient(ellipse 50% 40% at 20% 60%, rgba(59, 130, 246, 0.06), transparent);
    animation: heroPulse 8s ease-in-out infinite alternate;
}

@keyframes heroPulse {
    0% { opacity: 0.7; transform: scale(1); }
    100% { opacity: 1; transform: scale(1.05); }
}

.hero-content {
    position: relative;
    z-index: 1;
    max-width: 700px;
    padding: 2rem;
}

.hero-badge {
    display: inline-block;
    padding: 0.4rem 1.2rem;
    background: rgba(99, 102, 241, 0.12);
    border: 1px solid rgba(99, 102, 241, 0.25);
    border-radius: 100px;
    font-size: 0.8rem;
    font-weight: 500;
    color: var(--accent-primary);
    letter-spacing: 0.05em;
    margin-bottom: 1.5rem;
    animation: fadeInUp 0.6s ease-out;
}

.hero h1 {
    font-size: clamp(3rem, 8vw, 5.5rem);
    font-weight: 800;
    line-height: 1.1;
    margin-bottom: 1rem;
    animation: fadeInUp 0.6s ease-out 0.1s both;
}

.gradient-text {
    background: var(--accent-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero-subtitle {
    font-size: 1.15rem;
    color: var(--text-secondary);
    max-width: 500px;
    margin: 0 auto 2.5rem;
    animation: fadeInUp 0.6s ease-out 0.2s both;
}

.hero-stats {
    display: flex;
    gap: 2.5rem;
    justify-content: center;
    margin-bottom: 2.5rem;
    animation: fadeInUp 0.6s ease-out 0.3s both;
}

.stat-item {
    display: flex;
    flex-direction: column;
    align-items: center;
}

.stat-value {
    font-size: 1.8rem;
    font-weight: 700;
    background: var(--accent-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.stat-label {
    font-size: 0.78rem;
    color: var(--text-muted);
    text-transform: uppercase;
    letter-spacing: 0.08em;
    margin-top: 0.2rem;
}

.cta-btn {
    display: inline-flex;
    align-items: center;
    gap: 0.6rem;
    padding: 0.9rem 2rem;
    background: var(--accent-gradient);
    color: #fff;
    border: none;
    border-radius: 100px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    text-decoration: none;
    transition: var(--transition);
    animation: fadeInUp 0.6s ease-out 0.4s both;
}
.cta-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 30px rgba(99, 102, 241, 0.4);
    text-decoration: none;
}

@keyframes fadeInUp {
    from { opacity: 0; transform: translateY(20px); }
    to { opacity: 1; transform: translateY(0); }
}


/* ═══════════════ SECTIONS ═══════════════ */
.section {
    padding: 4rem 0;
}

.section-header {
    text-align: center;
    margin-bottom: 2.5rem;
}
.section-header h2 {
    font-size: 1.8rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
}
.section-header h3 {
    font-size: 1.3rem;
    font-weight: 600;
    margin-bottom: 0.4rem;
}
.section-header p {
    color: var(--text-secondary);
    font-size: 0.95rem;
}


/* ═══════════════ SAMPLE BAR ═══════════════ */
.sample-bar {
    display: flex;
    align-items: center;
    gap: 1rem;
    padding: 1rem 1.5rem;
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    margin-bottom: 2rem;
    overflow-x: auto;
}

.sample-label {
    font-size: 0.85rem;
    font-weight: 600;
    color: var(--text-muted);
    white-space: nowrap;
}

.sample-buttons {
    display: flex;
    gap: 0.6rem;
    flex-wrap: wrap;
}

.sample-btn {
    padding: 0.45rem 1rem;
    background: rgba(99, 102, 241, 0.1);
    border: 1px solid rgba(99, 102, 241, 0.2);
    border-radius: 100px;
    color: var(--accent-primary);
    font-size: 0.82rem;
    font-weight: 500;
    font-family: var(--font-sans);
    cursor: pointer;
    transition: var(--transition);
    white-space: nowrap;
}
.sample-btn:hover:not(:disabled) {
    background: rgba(99, 102, 241, 0.2);
    border-color: var(--accent-primary);
    transform: translateY(-1px);
}
.sample-btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}
.sample-btn.loading {
    color: var(--text-muted);
    background: transparent;
}


/* ═══════════════ FORM ═══════════════ */
.feature-form {
    max-width: 900px;
    margin: 0 auto;
}

.form-group {
    margin-bottom: 1.5rem;
}

.form-group label {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-size: 0.9rem;
    font-weight: 600;
    margin-bottom: 0.5rem;
    color: var(--text-primary);
}

.label-icon {
    font-size: 1.1rem;
}

.input-field {
    width: 100%;
    padding: 0.75rem 1rem;
    background: rgba(15, 23, 42, 0.8);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-sm);
    color: var(--text-primary);
    font-family: var(--font-mono);
    font-size: 0.92rem;
    transition: var(--transition);
}
.input-field:focus {
    outline: none;
    border-color: var(--accent-primary);
    box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.15);
}
.input-field::placeholder {
    color: var(--text-muted);
}

.input-hint {
    font-size: 0.78rem;
    color: var(--text-muted);
    margin-top: 0.3rem;
    display: block;
}

.age-group {
    max-width: 350px;
}

.form-divider {
    display: flex;
    align-items: center;
    gap: 1rem;
    margin: 2rem 0 1.5rem;
    color: var(--text-muted);
    font-size: 0.85rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.06em;
}
.form-divider::before,
.form-divider::after {
    content: '';
    flex: 1;
    height: 1px;
    background: var(--border-color);
}

.features-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: 1.2rem;
}

.feature-input-card {
    padding: 1rem 1.2rem;
    background: rgba(15, 23, 42, 0.5);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    transition: var(--transition);
}
.feature-input-card:hover {
    border-color: var(--border-glow);
}
.feature-input-card label {
    font-size: 0.82rem;
    margin-bottom: 0.4rem;
}
.feature-input-card .input-field {
    font-size: 0.88rem;
    padding: 0.6rem 0.8rem;
}
.feature-unit {
    font-size: 0.72rem;
    color: var(--text-muted);
    margin-top: 0.2rem;
}

.form-actions {
    display: flex;
    gap: 1rem;
    justify-content: center;
    margin-top: 2.5rem;
}

.btn-primary {
    padding: 0.9rem 2.5rem;
    background: var(--accent-gradient);
    color: #fff;
    border: none;
    border-radius: 100px;
    font-size: 1rem;
    font-weight: 600;
    font-family: var(--font-sans);
    cursor: pointer;
    transition: var(--transition);
    min-width: 220px;
}
.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 30px rgba(99, 102, 241, 0.4);
}
.btn-primary:disabled {
    opacity: 0.5;
    cursor: not-allowed;
    transform: none;
    box-shadow: none;
}

.btn-secondary {
    padding: 0.9rem 2rem;
    background: transparent;
    color: var(--text-secondary);
    border: 1px solid var(--border-color);
    border-radius: 100px;
    font-size: 0.95rem;
    font-weight: 500;
    font-family: var(--font-sans);
    cursor: pointer;
    transition: var(--transition);
}
.btn-secondary:hover {
    border-color: var(--text-muted);
    color: var(--text-primary);
}

.spinner {
    display: inline-block;
    width: 16px;
    height: 16px;
    border: 2px solid rgba(255,255,255,0.3);
    border-top-color: #fff;
    border-radius: 50%;
    animation: spin 0.6s linear infinite;
    vertical-align: middle;
}
@keyframes spin {
    to { transform: rotate(360deg); }
}


/* ═══════════════════ KNOWLEDGE HUB ═══════════════════ */
.knowledge-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 2rem;
    margin-top: 3rem;
}

.knowledge-card {
    background: var(--glass-bg);
    border: 1px solid var(--glass-border);
    border-radius: 20px;
    padding: 2.5rem;
    transition: all 0.4s cubic-bezier(0.175, 0.885, 0.32, 1.275);
    position: relative;
    overflow: hidden;
    backdrop-filter: blur(12px);
}

.knowledge-card:hover {
    transform: translateY(-10px);
    border-color: var(--accent-primary);
    box-shadow: 0 20px 40px rgba(0,0,0,0.3), 0 0 20px rgba(99, 102, 241, 0.2);
}

.card-icon {
    font-size: 2.5rem;
    margin-bottom: 1.5rem;
    display: block;
}

.knowledge-card h3 {
    font-size: 1.4rem;
    color: var(--text-primary);
    margin-bottom: 1rem;
    font-weight: 700;
}

.knowledge-card p {
    font-size: 0.95rem;
    line-height: 1.6;
    color: var(--text-secondary);
}

.band-list {
    margin-top: 1rem;
    display: flex;
    flex-direction: column;
    gap: 0.8rem;
}

.band-item {
    font-size: 0.85rem;
    line-height: 1.4;
    padding-left: 1rem;
    border-left: 2px solid var(--accent-primary);
    color: var(--text-secondary);
}

.band-item strong {
    color: var(--text-primary);
    display: block;
    margin-bottom: 0.2rem;
}

.cta-btn.secondary {
    background: transparent;
    border: 1px solid var(--glass-border);
    margin-right: 1rem;
}

.cta-btn.secondary:hover {
    background: var(--glass-bg);
    border-color: var(--text-primary);
}


/* ═══════════════ RESULTS ═══════════════ */
.results-section {
    animation: fadeInUp 0.5s ease-out;
}

.results-hero {
    display: grid;
    grid-template-columns: 1fr 1fr 1fr;
    gap: 1.5rem;
    margin-bottom: 3rem;
}

.gauge-card, .gap-card, .model-card {
    text-align: center;
}
.gauge-card h3, .gap-card h3, .model-card h3 {
    font-size: 0.9rem;
    color: var(--text-muted);
    text-transform: uppercase;
    letter-spacing: 0.05em;
    margin-bottom: 1rem;
}

.gauge-container {
    position: relative;
    display: flex;
    flex-direction: column;
    align-items: center;
}
.gauge-value {
    font-size: 2.8rem;
    font-weight: 800;
    margin-top: -2rem;
    background: var(--accent-gradient);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}
.gauge-label {
    font-size: 0.85rem;
    color: var(--text-muted);
    margin-top: -0.3rem;
}

.gap-value {
    font-size: 3rem;
    font-weight: 800;
    margin: 1rem 0 0.5rem;
}
.gap-description {
    font-size: 0.88rem;
    color: var(--text-secondary);
    line-height: 1.5;
}

.model-info {
    text-align: left;
}
.detail-item {
    display: flex;
    justify-content: space-between;
    align-items: flex-start; /* Changed from center to handle multi-line model names */
    padding: 0.8rem 0;
    border-bottom: 1px solid var(--glass-border);
    gap: 1rem;
}

.detail-item:last-child {
    border-bottom: none;
}

.detail-label {
    color: var(--text-secondary);
    font-size: 0.85rem;
    white-space: nowrap;
}

.detail-value {
    color: var(--text-primary);
    font-weight: 500;
    text-align: right;
    font-size: 0.9rem;
}
/* ─── Assessment Card ─── */
.assessment-card {
    display: flex;
    align-items: center;
    gap: 1.5rem;
    margin-bottom: 3rem;
    transition: var(--transition);
}
.assessment-icon {
    font-size: 3rem;
    min-width: 4rem;
    text-align: center;
}
.assessment-content h3 {
    font-size: 1.3rem;
    font-weight: 700;
    margin-bottom: 0.4rem;
}
.assessment-content p {
    color: var(--text-secondary);
    font-size: 0.95rem;
}


/* ─── Charts ─── */
.shap-card, .importance-card {
    margin-bottom: 3rem;
    padding: 1.5rem;
}
.shap-card canvas, .importance-card canvas {
    width: 100% !important;
    height: auto !important;
}


/* ─── Recommendations ─── */
.recommendations-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
    gap: 1.2rem;
    margin-bottom: 2rem;
}

.rec-card {
    padding: 1.5rem;
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    transition: var(--transition);
}
.rec-card:hover {
    border-color: var(--border-glow);
    transform: translateY(-2px);
}

.rec-card.status-attention {
    border-left: 3px solid var(--amber);
    background: linear-gradient(135deg, var(--amber-soft), var(--bg-card));
}
.rec-card.status-positive {
    border-left: 3px solid var(--green);
    background: linear-gradient(135deg, var(--green-soft), var(--bg-card));
}
.rec-card.status-neutral {
    border-left: 3px solid var(--text-muted);
}

.rec-header {
    display: flex;
    align-items: center;
    gap: 0.8rem;
    margin-bottom: 0.8rem;
}
.rec-icon { font-size: 1.5rem; }
.rec-region {
    font-weight: 700;
    font-size: 1rem;
}
.rec-status {
    font-size: 0.72rem;
    font-weight: 600;
    padding: 0.2rem 0.6rem;
    border-radius: 100px;
    margin-left: auto;
}
.rec-card.status-attention .rec-status {
    background: var(--amber-soft);
    color: var(--amber);
}
.rec-card.status-positive .rec-status {
    background: var(--green-soft);
    color: var(--green);
}
.rec-card.status-neutral .rec-status {
    background: rgba(100,116,139,0.15);
    color: var(--text-muted);
}

.rec-value {
    font-family: var(--font-mono);
    font-size: 0.82rem;
    color: var(--text-secondary);
    margin-bottom: 0.7rem;
}

.rec-tips {
    list-style: none;
    padding: 0;
}
.rec-tips li {
    font-size: 0.85rem;
    color: var(--text-secondary);
    padding: 0.3rem 0 0.3rem 1.2rem;
    position: relative;
    line-height: 1.5;
}
.rec-tips li::before {
    content: '→';
    position: absolute;
    left: 0;
    color: var(--accent-primary);
}


/* ─── General Tips ─── */
.general-tips {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 1rem;
    margin-bottom: 3rem;
}

.tip-card {
    display: flex;
    gap: 1rem;
    align-items: flex-start;
    padding: 1.2rem;
    background: var(--bg-card);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    transition: var(--transition);
}
.tip-card:hover {
    border-color: var(--border-glow);
}
.tip-icon {
    font-size: 1.6rem;
    min-width: 2rem;
    text-align: center;
}
.tip-title {
    font-weight: 700;
    font-size: 0.95rem;
    margin-bottom: 0.3rem;
}
.tip-detail {
    font-size: 0.83rem;
    color: var(--text-secondary);
    line-height: 1.5;
}


/* ═══════════════ MODEL SELECTOR ═══════════════ */
.model-selector {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
    gap: 0.8rem;
    margin-bottom: 2rem;
}

.model-option {
    padding: 1rem 1.2rem;
    background: var(--bg-card);
    border: 1.5px solid var(--border-color);
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: var(--transition);
    text-align: left;
    font-family: var(--font-sans);
    color: var(--text-primary);
}
.model-option:hover {
    border-color: var(--accent-primary);
    transform: translateY(-2px);
}
.model-option.active {
    border-color: var(--accent-primary);
    background: rgba(99, 102, 241, 0.1);
    box-shadow: 0 0 15px rgba(99, 102, 241, 0.2);
}
.model-option-name {
    font-weight: 700;
    font-size: 0.95rem;
    margin-bottom: 0.3rem;
}
.model-option-desc {
    font-size: 0.75rem;
    color: var(--text-muted);
    line-height: 1.4;
}
.model-option-score {
    margin-top: 0.5rem;
    font-family: var(--font-mono);
    font-size: 0.78rem;
    color: var(--accent-primary);
}

/* ═══════════════ COMPARISON TABLE ═══════════════ */
.comparison-table {
    width: 100%;
    border-collapse: collapse;
    font-size: 0.88rem;
}
.comparison-table th {
    text-align: left;
    padding: 0.7rem 1rem;
    color: var(--text-muted);
    font-weight: 600;
    font-size: 0.78rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    border-bottom: 1px solid var(--border-color);
}
.comparison-table td {
    padding: 0.7rem 1rem;
    border-bottom: 1px solid rgba(255,255,255,0.03);
    color: var(--text-secondary);
}
.comparison-table tr:last-child td { border-bottom: none; }
.comparison-table tr.active-row {
    background: rgba(99, 102, 241, 0.08);
}
.comparison-table tr.active-row td {
    color: var(--text-primary);
    font-weight: 500;
}
.comparison-table .best-score {
    color: var(--green);
    font-weight: 600;
}

/* ═══════════════ FOOTER ═══════════════ */
.footer {
    padding: 2rem 0;
    text-align: center;
    border-top: 1px solid var(--border-color);
    color: var(--text-muted);
    font-size: 0.85rem;
}
.footer p { margin-bottom: 0.5rem; }
.footer strong { color: var(--text-secondary); }
.disclaimer {
    font-size: 0.78rem;
    color: var(--text-muted);
    max-width: 600px;
    margin: 0.5rem auto 0;
}


/* ═══════════════ RESPONSIVE ═══════════════ */
@media (max-width: 768px) {
    .hero h1 { font-size: 2.8rem; }
    .hero-stats { gap: 1.5rem; }
    .stat-value { font-size: 1.4rem; }
    .results-hero {
        grid-template-columns: 1fr;
    }
    .features-grid {
        grid-template-columns: 1fr;
    }
    .recommendations-grid {
        grid-template-columns: 1fr;
    }
    .general-tips {
        grid-template-columns: 1fr;
    }
    .form-actions {
        flex-direction: column;
        align-items: stretch;
    }
    .assessment-card {
        flex-direction: column;
        text-align: center;
    }
}