/* CSS Variables - Professional, clean palette */
:root {
    --primary-color: #0f766e;
    --primary-light: #14b8a6;
    --primary-dark: #0d9488;
    --accent-color: #0284c7;
    --background: #fafafa;
    --background-alt: #ffffff;
    --surface: #ffffff;
    --surface-hover: #f8fafc;
    --text-primary: #0f172a;
    --text-secondary: #475569;
    --text-muted: #94a3b8;
    --border-color: #e2e8f0;
    --border-light: #f1f5f9;
    --success: #059669;
    --warning: #d97706;
    --error: #dc2626;
    --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    --font-mono: 'JetBrains Mono', 'Fira Code', monospace;
    --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.04);
    --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.05);
    --shadow-lg: 0 8px 24px rgba(0, 0, 0, 0.08);
    --radius-sm: 6px;
    --radius-md: 8px;
    --radius-lg: 12px;
}

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

html {
    scroll-behavior: smooth;
    scroll-padding-top: 70px;
}

body {
    font-family: var(--font-sans);
    background-color: var(--background);
    color: var(--text-primary);
    line-height: 1.6;
    font-size: 16px;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

a {
    color: var(--primary-color);
    text-decoration: none;
    transition: color 0.2s ease;
}

a:hover {
    color: var(--primary-dark);
    text-decoration: underline;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 24px;
}

/* Hero Section */
.hero {
    background: linear-gradient(180deg, #f0fdfa 0%, var(--background) 100%);
    padding: 80px 0 60px;
    text-align: center;
    border-bottom: 1px solid var(--border-color);
}

.hero h1 {
    font-size: 2.75rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 16px;
    letter-spacing: -0.02em;
    line-height: 1.2;
}

.hero .subtitle {
    font-size: 1.125rem;
    color: var(--text-secondary);
    max-width: 600px;
    margin: 0 auto 24px;
    line-height: 1.7;
}

.last-updated {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    font-size: 0.875rem;
    color: var(--text-muted);
    font-family: var(--font-mono);
    padding: 8px 16px;
    background: var(--surface);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
}

.last-updated::before {
    content: '';
    width: 8px;
    height: 8px;
    background: var(--success);
    border-radius: 50%;
}

/* Sticky Navigation */
.sticky-nav {
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(8px);
    -webkit-backdrop-filter: blur(8px);
    border-bottom: 1px solid var(--border-color);
    position: sticky;
    top: 0;
    z-index: 100;
}

.sticky-nav ul {
    display: flex;
    justify-content: center;
    list-style: none;
    gap: 4px;
    padding: 12px 0;
    overflow-x: auto;
    -webkit-overflow-scrolling: touch;
}

.sticky-nav a {
    color: var(--text-secondary);
    padding: 8px 16px;
    border-radius: var(--radius-md);
    font-weight: 500;
    font-size: 0.9rem;
    white-space: nowrap;
    transition: all 0.2s ease;
}

.sticky-nav a:hover,
.sticky-nav a.active {
    color: var(--primary-color);
    background: #f0fdfa;
    text-decoration: none;
}

/* Sections */
.section {
    padding: 64px 0;
    border-bottom: 1px solid var(--border-color);
}

.section h2 {
    font-size: 1.75rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 8px;
    letter-spacing: -0.01em;
}

.section-intro {
    color: var(--text-secondary);
    font-size: 1.0625rem;
    margin-bottom: 32px;
    max-width: 640px;
}

/* Filter Controls */
.filter-controls {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    margin-bottom: 32px;
}

.filter-btn {
    padding: 8px 16px;
    border: 1px solid var(--border-color);
    background: var(--surface);
    color: var(--text-secondary);
    border-radius: var(--radius-md);
    cursor: pointer;
    font-size: 0.875rem;
    font-weight: 500;
    transition: all 0.2s ease;
}

.filter-btn:hover {
    border-color: var(--primary-color);
    color: var(--primary-color);
    background: #f0fdfa;
}

.filter-btn.active {
    background: var(--primary-color);
    border-color: var(--primary-color);
    color: white;
}

/* Card Base Styles */
.finding-card,
.question-card,
.technique-card,
.paper-card,
.update-card {
    background: var(--surface);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    transition: all 0.2s ease;
}

.finding-card:hover,
.technique-card:hover,
.paper-card:hover {
    border-color: var(--border-color);
    box-shadow: var(--shadow-lg);
    transform: translateY(-2px);
}

/* Findings Grid */
.findings-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(360px, 1fr));
    gap: 20px;
}

.finding-card {
    padding: 24px;
}

.finding-card .category {
    display: inline-block;
    font-size: 0.75rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    padding: 4px 10px;
    border-radius: var(--radius-sm);
    margin-bottom: 12px;
}

.finding-card .category.features {
    background: #dbeafe;
    color: #1e40af;
}
.finding-card .category.circuits {
    background: #d1fae5;
    color: #065f46;
}
.finding-card .category.superposition {
    background: #fef3c7;
    color: #92400e;
}
.finding-card .category.safety {
    background: #fee2e2;
    color: #991b1b;
}

.finding-card h3 {
    font-size: 1.0625rem;
    font-weight: 600;
    margin-bottom: 10px;
    color: var(--text-primary);
    line-height: 1.4;
}

.finding-card p {
    color: var(--text-secondary);
    font-size: 0.9375rem;
    margin-bottom: 16px;
    line-height: 1.65;
}

.finding-card .meta {
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-size: 0.8125rem;
    color: var(--text-muted);
    padding-top: 16px;
    border-top: 1px solid var(--border-light);
}

.finding-card .source {
    display: flex;
    align-items: center;
    gap: 6px;
}

/* Open Questions */
.questions-list {
    display: flex;
    flex-direction: column;
    gap: 16px;
}

.question-card {
    padding: 24px;
    border-left: 3px solid var(--primary-color);
}

.question-card h3 {
    font-size: 1.0625rem;
    font-weight: 600;
    margin-bottom: 10px;
    color: var(--text-primary);
}

.question-card p {
    color: var(--text-secondary);
    font-size: 0.9375rem;
    margin-bottom: 12px;
    line-height: 1.65;
}

.question-card .importance {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    font-size: 0.8125rem;
    font-weight: 500;
    color: var(--warning);
}

.question-card .importance::before {
    content: '';
    display: inline-block;
    width: 6px;
    height: 6px;
    background: currentColor;
    border-radius: 50%;
}

.question-card.critical { border-left-color: var(--error); }
.question-card.critical .importance { color: var(--error); }

/* Techniques Grid */
.techniques-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
    gap: 20px;
}

.technique-card {
    padding: 24px;
    border-top: 3px solid var(--primary-color);
}

.technique-card h3 {
    font-size: 1.0625rem;
    font-weight: 600;
    margin-bottom: 10px;
    color: var(--text-primary);
}

.technique-card p {
    color: var(--text-secondary);
    font-size: 0.9375rem;
    margin-bottom: 12px;
    line-height: 1.65;
}

.technique-card .papers-count {
    font-size: 0.8125rem;
    color: var(--text-muted);
    font-family: var(--font-mono);
}

/* Papers Section */
.papers-controls {
    display: flex;
    gap: 12px;
    margin-bottom: 32px;
    flex-wrap: wrap;
}

.search-input {
    flex: 1;
    min-width: 260px;
    padding: 10px 16px;
    background: var(--surface);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    color: var(--text-primary);
    font-size: 0.9375rem;
    transition: all 0.2s ease;
}

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

.search-input:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(15, 118, 110, 0.1);
}

.sort-select {
    padding: 10px 16px;
    background: var(--surface);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    color: var(--text-primary);
    font-size: 0.9375rem;
    cursor: pointer;
}

.sort-select:focus {
    outline: none;
    border-color: var(--primary-color);
}

.papers-list {
    display: flex;
    flex-direction: column;
    gap: 16px;
    max-height: 600px;
    overflow-y: auto;
    padding-right: 8px;
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: 16px;
    background: var(--background);
}

/* Custom scrollbar for papers list */
.papers-list::-webkit-scrollbar {
    width: 8px;
}

.papers-list::-webkit-scrollbar-track {
    background: var(--background);
    border-radius: 4px;
}

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

.papers-list::-webkit-scrollbar-thumb:hover {
    background: var(--text-muted);
}

.paper-card {
    padding: 20px;
    display: flex;
    gap: 20px;
}

.paper-date {
    flex-shrink: 0;
    text-align: center;
    padding: 10px 12px;
    background: var(--background);
    border-radius: var(--radius-md);
    min-width: 64px;
}

.paper-date .month {
    font-size: 0.6875rem;
    text-transform: uppercase;
    color: var(--text-muted);
    font-weight: 600;
    letter-spacing: 0.05em;
}

.paper-date .day {
    font-size: 1.375rem;
    font-weight: 700;
    color: var(--text-primary);
    line-height: 1.2;
}

.paper-date .year {
    font-size: 0.6875rem;
    color: var(--text-muted);
}

.paper-content {
    flex: 1;
}

.paper-content h3 {
    font-size: 1rem;
    font-weight: 600;
    margin-bottom: 6px;
    color: var(--text-primary);
    line-height: 1.4;
}

.paper-content h3 a {
    color: inherit;
}

.paper-content h3 a:hover {
    color: var(--primary-color);
}

.paper-authors {
    font-size: 0.875rem;
    color: var(--text-muted);
    margin-bottom: 8px;
}

.paper-abstract {
    font-size: 0.9rem;
    color: var(--text-secondary);
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
    line-height: 1.6;
}

.paper-tags {
    display: flex;
    gap: 6px;
    margin-top: 12px;
    flex-wrap: wrap;
}

.paper-tag {
    font-size: 0.6875rem;
    font-weight: 500;
    padding: 3px 8px;
    background: var(--background);
    border-radius: var(--radius-sm);
    color: var(--text-muted);
}

.load-more-container {
    text-align: center;
    margin-top: 32px;
}

.load-more-btn {
    padding: 10px 28px;
    background: var(--surface);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-md);
    color: var(--text-primary);
    font-size: 0.9375rem;
    font-weight: 500;
    cursor: pointer;
    transition: all 0.2s ease;
}

.load-more-btn:hover {
    background: var(--surface-hover);
    border-color: var(--primary-color);
}

/* Resources Section */
.resources-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
    gap: 32px;
}

.resource-category h3 {
    font-size: 1rem;
    font-weight: 600;
    margin-bottom: 16px;
    color: var(--text-primary);
    padding-bottom: 10px;
    border-bottom: 2px solid var(--primary-color);
    display: inline-block;
}

.resource-category ul {
    list-style: none;
}

.resource-category li {
    margin-bottom: 8px;
}

.resource-category a {
    color: var(--text-secondary);
    font-size: 0.9375rem;
    display: block;
    padding: 6px 0;
    transition: color 0.2s ease;
}

.resource-category a:hover {
    color: var(--primary-color);
    text-decoration: none;
}

/* Updates Section */
.updates-section {
    background: linear-gradient(180deg, var(--background) 0%, #f0fdfa 100%);
    border-radius: var(--radius-lg);
    margin: 32px 0;
    padding: 40px;
    border: 1px solid var(--border-color);
}

.updates-section::before {
    display: none;
}

.update-info {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
    gap: 20px;
    margin-top: 24px;
}

.update-card {
    background: var(--surface);
    padding: 20px;
}

.update-card h4 {
    font-size: 0.9375rem;
    font-weight: 600;
    margin-bottom: 8px;
    color: var(--text-primary);
}

.update-card p {
    font-size: 0.875rem;
    color: var(--text-secondary);
    line-height: 1.6;
}

/* Footer */
footer {
    background: var(--surface);
    border-top: 1px solid var(--border-color);
    padding: 40px 0;
    text-align: center;
}

footer p {
    color: var(--text-muted);
    font-size: 0.875rem;
    margin-bottom: 8px;
}

footer a {
    color: var(--text-secondary);
}

footer a:hover {
    color: var(--primary-color);
}

/* Responsive */
@media (max-width: 768px) {
    .hero {
        padding: 48px 0 40px;
    }

    .hero h1 {
        font-size: 2rem;
    }

    .hero .subtitle {
        font-size: 1rem;
    }

    .section {
        padding: 48px 0;
    }

    .section h2 {
        font-size: 1.5rem;
    }

    .findings-grid,
    .techniques-grid {
        grid-template-columns: 1fr;
    }

    .papers-list {
        max-height: 400px;
    }

    .paper-card {
        flex-direction: column;
    }

    .paper-date {
        display: flex;
        gap: 8px;
        align-items: baseline;
        width: fit-content;
    }

    .sticky-nav ul {
        justify-content: flex-start;
        gap: 0;
    }

    .sticky-nav a {
        padding: 8px 12px;
        font-size: 0.85rem;
    }

    .container {
        padding: 0 16px;
    }

    .updates-section {
        padding: 24px;
        margin: 24px 0;
    }
}

/* Animations */
@keyframes fadeIn {
    from { opacity: 0; transform: translateY(8px); }
    to { opacity: 1; transform: translateY(0); }
}

.finding-card,
.question-card,
.technique-card,
.paper-card {
    animation: fadeIn 0.3s ease forwards;
}

/* Highlight for new items */
.new-badge {
    background: var(--success);
    color: white;
    font-size: 0.625rem;
    font-weight: 600;
    padding: 2px 6px;
    border-radius: var(--radius-sm);
    text-transform: uppercase;
    letter-spacing: 0.03em;
    margin-left: 8px;
}

/* Featured badge */
.featured-badge {
    background: var(--primary-color);
    color: white;
    font-size: 0.625rem;
    font-weight: 600;
    padding: 2px 6px;
    border-radius: var(--radius-sm);
    text-transform: uppercase;
    letter-spacing: 0.03em;
    margin-left: 8px;
}

/* Papers sections */
.papers-section {
    margin-bottom: 32px;
}

.papers-section:last-child {
    margin-bottom: 0;
}

.papers-section-title {
    font-size: 1.125rem;
    font-weight: 600;
    color: var(--text-primary);
    margin-bottom: 4px;
}

.papers-section-desc {
    font-size: 0.875rem;
    color: var(--text-muted);
    margin-bottom: 16px;
}

.paper-card.featured {
    border-left: 3px solid var(--primary-color);
    background: linear-gradient(90deg, rgba(15, 118, 110, 0.03) 0%, transparent 100%);
}

/* Selection */
::selection {
    background: rgba(15, 118, 110, 0.15);
    color: var(--text-primary);
}

/* Focus visible for accessibility */
:focus-visible {
    outline: 2px solid var(--primary-color);
    outline-offset: 2px;
}

/* Neuroscience Comparison Section */
.neuro-comparisons-grid {
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.neuro-comparison-card {
    background: var(--surface);
    border: 1px solid var(--border-color);
    border-radius: var(--radius-lg);
    padding: 24px;
    transition: all 0.2s ease;
}

.neuro-comparison-card:hover {
    box-shadow: var(--shadow-lg);
}

.comparison-header {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 20px;
    margin-bottom: 20px;
    padding-bottom: 16px;
    border-bottom: 1px solid var(--border-light);
    flex-wrap: wrap;
}

.concept {
    display: flex;
    flex-direction: column;
    align-items: center;
    text-align: center;
    min-width: 140px;
}

.concept-label {
    font-size: 0.6875rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    margin-bottom: 4px;
}

.ai-concept .concept-label {
    color: var(--primary-color);
}

.neuro-concept .concept-label {
    color: var(--accent-color);
}

.concept-name {
    font-size: 1rem;
    font-weight: 600;
    color: var(--text-primary);
}

.comparison-arrow {
    font-size: 1.5rem;
    color: var(--text-muted);
    flex-shrink: 0;
}

.comparison-text {
    color: var(--text-secondary);
    font-size: 0.9375rem;
    line-height: 1.7;
    margin-bottom: 16px;
}

.comparison-implication {
    background: var(--background);
    padding: 12px 16px;
    border-radius: var(--radius-md);
    font-size: 0.875rem;
    color: var(--text-secondary);
    margin-bottom: 12px;
}

.comparison-implication strong {
    color: var(--text-primary);
}

.comparison-source {
    font-size: 0.875rem;
    font-weight: 500;
    color: var(--primary-color);
    display: inline-block;
}

.comparison-source:hover {
    text-decoration: underline;
}

@media (max-width: 768px) {
    .comparison-header {
        flex-direction: column;
        gap: 12px;
    }

    .comparison-arrow {
        transform: rotate(90deg);
    }
}