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

:root {
    --bg-primary: #0a0a0f;
    --bg-secondary: #12121a;
    --bg-card: #1a1a28;
    --bg-card-hover: #222236;
    --text-primary: #e8e8f0;
    --text-secondary: #9090a8;
    --text-muted: #606078;
    --accent-1: #6c63ff;
    --accent-2: #00c9a7;
    --accent-3: #ff6b6b;
    --accent-4: #ffd93d;
    --border: #2a2a3e;
    --radius: 12px;
    --radius-sm: 8px;
    --shadow: 0 2px 20px rgba(0,0,0,0.3);
    --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
    --font-serif: 'Source Serif 4', Georgia, serif;
}

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;
}

/* === Navbar === */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    background: rgba(10,10,15,0.85);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    border-bottom: 1px solid var(--border);
}

.nav-inner {
    max-width: 1400px;
    margin: 0 auto;
    padding: 0 2rem;
    height: 60px;
    display: flex;
    align-items: center;
    gap: 2rem;
}

.logo {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--text-primary);
    text-decoration: none;
    letter-spacing: -0.02em;
    background: linear-gradient(135deg, var(--accent-1), var(--accent-2));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.nav-links {
    display: flex;
    gap: 1.5rem;
    margin-left: auto;
}

.nav-links a {
    color: var(--text-secondary);
    text-decoration: none;
    font-size: 0.875rem;
    font-weight: 500;
    transition: color 0.2s;
    position: relative;
}

.nav-links a:hover,
.nav-links a.active {
    color: var(--text-primary);
}

.nav-links a.active::after {
    content: '';
    position: absolute;
    bottom: -4px;
    left: 0;
    right: 0;
    height: 2px;
    background: var(--accent-1);
    border-radius: 2px;
}

.nav-week {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.25rem 0.75rem;
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: 20px;
    font-size: 0.75rem;
}

.week-label {
    color: var(--text-muted);
}

.week-value {
    color: var(--accent-1);
    font-weight: 600;
}

/* === Hero === */
.hero {
    position: relative;
    min-height: 70vh;
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
    padding: 120px 2rem 4rem;
}

.hero-bg {
    position: absolute;
    inset: 0;
    background:
        radial-gradient(ellipse at 20% 50%, rgba(108,99,255,0.08) 0%, transparent 50%),
        radial-gradient(ellipse at 80% 50%, rgba(0,201,167,0.06) 0%, transparent 50%);
    pointer-events: none;
}

.hero-content {
    position: relative;
    text-align: center;
    max-width: 800px;
}

.hero h1 {
    font-size: 3.25rem;
    font-weight: 700;
    line-height: 1.2;
    margin-bottom: 1.5rem;
    letter-spacing: -0.03em;
}

.hero .accent {
    background: linear-gradient(135deg, var(--accent-1), #8b7fff);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero .accent2 {
    background: linear-gradient(135deg, var(--accent-2), #00e6bf);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero-sub {
    font-size: 1.1rem;
    color: var(--text-secondary);
    line-height: 1.7;
    margin-bottom: 3rem;
}

.hero-stats {
    display: flex;
    justify-content: center;
    gap: 4rem;
}

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

.stat-num {
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--text-primary);
    letter-spacing: -0.03em;
}

.stat-label {
    font-size: 0.85rem;
    color: var(--text-muted);
    margin-top: 0.25rem;
}

/* === Section Common === */
section {
    padding: 4rem 2rem;
}

.section-header {
    max-width: 1400px;
    margin: 0 auto 2rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.section-header h2 {
    font-size: 1.5rem;
    font-weight: 600;
}

.view-all {
    color: var(--accent-1);
    text-decoration: none;
    font-size: 0.875rem;
    font-weight: 500;
    transition: opacity 0.2s;
}

.view-all:hover {
    opacity: 0.7;
}

/* === Graph Section === */
.graph-section {
    background: var(--bg-secondary);
}

.graph-controls {
    display: flex;
    gap: 0.5rem;
}

.btn-filter {
    padding: 0.4rem 1rem;
    border: 1px solid var(--border);
    background: var(--bg-card);
    color: var(--text-secondary);
    border-radius: 20px;
    font-size: 0.8rem;
    cursor: pointer;
    transition: all 0.2s;
    font-family: var(--font-sans);
}

.btn-filter:hover,
.btn-filter.active {
    background: var(--accent-1);
    border-color: var(--accent-1);
    color: #fff;
}

.graph-container {
    max-width: 1400px;
    margin: 0 auto;
    position: relative;
}

#knowledge-graph {
    width: 100%;
    height: 560px;
    background: var(--bg-primary);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    overflow: hidden;
}

.graph-tooltip {
    position: absolute;
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius-sm);
    padding: 1rem;
    max-width: 320px;
    pointer-events: none;
    box-shadow: var(--shadow);
    z-index: 100;
}

.graph-tooltip.hidden {
    display: none;
}

.graph-tooltip h4 {
    font-size: 0.9rem;
    margin-bottom: 0.4rem;
}

.graph-tooltip p {
    font-size: 0.8rem;
    color: var(--text-secondary);
    line-height: 1.5;
}

.graph-tooltip .tooltip-meta {
    font-size: 0.7rem;
    color: var(--text-muted);
    margin-top: 0.3rem;
}

/* === Journal Grid === */
.journal-grid,
.preprint-grid {
    max-width: 1400px;
    margin: 0 auto;
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(340px, 1fr));
    gap: 1.25rem;
}

.card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 1.5rem;
    transition: all 0.3s ease;
    cursor: pointer;
}

.card:hover {
    background: var(--bg-card-hover);
    transform: translateY(-2px);
    border-color: rgba(108,99,255,0.3);
}

.card-badge {
    display: inline-flex;
    align-items: center;
    gap: 0.3rem;
    padding: 0.2rem 0.6rem;
    background: rgba(108,99,255,0.15);
    color: var(--accent-1);
    border-radius: 4px;
    font-size: 0.7rem;
    font-weight: 600;
    letter-spacing: 0.03em;
    margin-bottom: 0.75rem;
}

.card-badge.nature { background: rgba(0,201,167,0.15); color: var(--accent-2); }
.card-badge.science { background: rgba(255,107,107,0.15); color: var(--accent-3); }
.card-badge.cell { background: rgba(108,99,255,0.15); color: var(--accent-1); }
.card-badge.preprint { background: rgba(255,217,61,0.15); color: var(--accent-4); }

.card h3 {
    font-size: 1rem;
    font-weight: 600;
    line-height: 1.4;
    margin-bottom: 0.5rem;
    color: var(--text-primary);
}

.card p {
    font-size: 0.85rem;
    color: var(--text-secondary);
    line-height: 1.6;
}

.card-meta {
    display: flex;
    align-items: center;
    gap: 1rem;
    margin-top: 1rem;
    font-size: 0.75rem;
    color: var(--text-muted);
}

.card-tags {
    display: flex;
    gap: 0.4rem;
    margin-top: 0.75rem;
    flex-wrap: wrap;
}

.tag {
    padding: 0.15rem 0.5rem;
    background: rgba(255,255,255,0.05);
    border-radius: 4px;
    font-size: 0.7rem;
    color: var(--text-muted);
}

/* === Connection Section === */
.connection-section {
    background: var(--bg-secondary);
}

.connection-list {
    max-width: 1400px;
    margin: 0 auto;
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.connection-card {
    display: flex;
    align-items: stretch;
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    overflow: hidden;
    transition: all 0.3s;
}

.connection-card:hover {
    border-color: rgba(108,99,255,0.3);
}

.conn-question,
.conn-solution {
    flex: 1;
    padding: 1.25rem;
}

.conn-label {
    font-size: 0.65rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.08em;
    margin-bottom: 0.5rem;
}

.conn-label.question {
    color: var(--accent-3);
}

.conn-label.solution {
    color: var(--accent-2);
}

.conn-question h4,
.conn-solution h4 {
    font-size: 0.9rem;
    font-weight: 500;
    line-height: 1.4;
    margin-bottom: 0.3rem;
}

.conn-question p,
.conn-solution p {
    font-size: 0.8rem;
    color: var(--text-secondary);
}

.conn-bridge {
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 0 1rem;
    color: var(--accent-1);
    font-size: 1.25rem;
    flex-shrink: 0;
}

/* === Footer === */
.footer {
    border-top: 1px solid var(--border);
    padding: 3rem 2rem;
}

.footer-inner {
    max-width: 1400px;
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.footer-brand p {
    font-size: 0.8rem;
    color: var(--text-muted);
    margin-top: 0.25rem;
}

.footer-links {
    display: flex;
    gap: 1.5rem;
}

.footer-links a {
    color: var(--text-muted);
    text-decoration: none;
    font-size: 0.85rem;
    transition: color 0.2s;
}

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

/* === Responsive === */
@media (max-width: 768px) {
    .hero h1 { font-size: 2rem; }
    .hero-stats { gap: 2rem; }
    .stat-num { font-size: 1.75rem; }
    .nav-links { display: none; }
    .journal-grid,
    .preprint-grid {
        grid-template-columns: 1fr;
    }
    .connection-card {
        flex-direction: column;
    }
    .conn-bridge {
        padding: 0.5rem;
        transform: rotate(90deg);
    }
}