/* ═══════════════════════════════════════════
   Concept Page — Dark Theme Styles
   Shared across all /library/concepts/* pages
   ═══════════════════════════════════════════ */

:root {
    --bg: #07090d;
    --bg-surface: #0d1117;
    --bg-card: #131820;
    --bg-card-hover: #1a2230;
    --text: #e6e8ec;
    --text-secondary: #8b919a;
    --text-muted: #565d68;
    --border: rgba(255,255,255,0.06);
    --border-hover: rgba(255,255,255,0.12);
    --accent: #C27C5A;
    --accent-light: rgba(194,124,90,0.15);
    --accent-hover: #d4906e;
    --sage: #8fa38c;
    --radius: 12px;
    --shadow-sm: 0 2px 8px rgba(0,0,0,0.2);
    --shadow-md: 0 4px 20px rgba(0,0,0,0.3);
    --font-serif: 'Libre Baskerville', Georgia, serif;
    --font-sans: 'Inter', system-ui, -apple-system, sans-serif;
    --max-w: 720px;
}

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

body {
    font-family: var(--font-sans);
    background: var(--bg);
    color: var(--text);
    line-height: 1.7;
    -webkit-font-smoothing: antialiased;
    padding-top: 52px; /* hub nav height */
}

/* ═══ HIDE OLD NAV (hub-nav from hub.css takes over) ═══ */
.top-nav { display: none; }

/* ═══ BREADCRUMB ═══ */
.breadcrumb {
    max-width: var(--max-w);
    margin: 2rem auto 0;
    padding: 0 2rem;
    font-size: 0.82rem;
    color: var(--text-muted);
}
.breadcrumb a { color: var(--accent); text-decoration: none; }
.breadcrumb a:hover { text-decoration: underline; }

/* ═══ HERO ═══ */
.concept-hero {
    max-width: var(--max-w);
    margin: 0 auto;
    padding: 3rem 2rem 2rem;
}
.concept-label {
    font-size: 0.75rem;
    text-transform: uppercase;
    letter-spacing: 0.15em;
    color: var(--accent);
    font-weight: 600;
    margin-bottom: 1rem;
}
.concept-hero h1 {
    font-family: var(--font-serif);
    font-size: clamp(2.2rem, 5vw, 3.2rem);
    font-weight: 300;
    line-height: 1.15;
    margin-bottom: 1.5rem;
    color: var(--text);
}
.concept-hero h1 em {
    font-style: italic;
    color: var(--accent);
}
.concept-lede {
    font-family: var(--font-serif);
    font-size: 1.25rem;
    font-style: italic;
    color: var(--text-secondary);
    line-height: 1.65;
    border-left: 3px solid var(--accent);
    padding-left: 1.5rem;
    margin-bottom: 0;
}

/* ═══ BODY ═══ */
.concept-body {
    max-width: var(--max-w);
    margin: 0 auto;
    padding: 0 2rem;
}
.concept-body h2 {
    font-family: var(--font-serif);
    font-size: 1.8rem;
    font-weight: 400;
    margin: 3.5rem 0 1rem;
    line-height: 1.2;
    color: var(--text);
}
.concept-body h3 {
    font-family: var(--font-serif);
    font-size: 1.3rem;
    font-weight: 500;
    margin: 2.5rem 0 0.75rem;
    color: var(--text);
}
.concept-body p {
    font-size: 1.02rem;
    line-height: 1.85;
    color: var(--text-secondary);
    margin-bottom: 1.25rem;
}
.concept-body strong { color: var(--text); }
.concept-body em { color: var(--text-secondary); }
.concept-body ul, .concept-body ol {
    padding-left: 1.5rem;
    margin-bottom: 1.25rem;
    color: var(--text-secondary);
}
.concept-body li {
    margin-bottom: 0.5rem;
    line-height: 1.85;
}

/* ═══ COMPARISON TABLE ═══ */
.compare-table {
    width: 100%;
    border-collapse: collapse;
    margin: 2rem 0;
    font-size: 0.92rem;
}
.compare-table th {
    text-align: left;
    padding: 1rem;
    font-family: var(--font-serif);
    font-size: 1.05rem;
    font-weight: 500;
    border-bottom: 2px solid var(--text-muted);
    color: var(--text);
}
.compare-table td {
    padding: 0.85rem 1rem;
    border-bottom: 1px solid var(--border);
    color: var(--text-secondary);
    vertical-align: top;
}
.compare-table tr td:first-child {
    font-weight: 500;
    color: var(--text);
    width: 30%;
}
.compare-table .col-achieve { background: rgba(200,80,80,0.08); }
.compare-table .col-converge { background: var(--accent-light); }

/* ═══ BLOCKQUOTE ═══ */
.concept-quote {
    border-left: 3px solid var(--accent);
    padding: 1.5rem 2rem;
    margin: 2.5rem 0;
    background: var(--accent-light);
    border-radius: 0 var(--radius) var(--radius) 0;
}
.concept-quote p {
    font-family: var(--font-serif);
    font-size: 1.15rem;
    font-style: italic;
    color: var(--text-secondary);
    line-height: 1.65;
    margin-bottom: 0;
}
.concept-quote cite {
    display: block;
    margin-top: 0.75rem;
    font-size: 0.85rem;
    font-style: normal;
    color: var(--text-muted);
}

/* ═══ SUPPORTING ARTICLES ═══ */
.reading-section {
    max-width: var(--max-w);
    margin: 0 auto;
    padding: 3rem 2rem 1rem;
}
.reading-section h2 {
    font-family: var(--font-serif);
    font-size: 1.8rem;
    font-weight: 400;
    margin-bottom: 0.5rem;
    color: var(--text);
}
.reading-section > p {
    font-size: 0.95rem;
    color: var(--text-muted);
    margin-bottom: 2rem;
}
.reading-card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 1.75rem;
    margin-bottom: 1.25rem;
    text-decoration: none;
    color: inherit;
    display: block;
    transition: all 0.2s;
}
.reading-card:hover {
    border-color: var(--accent);
    box-shadow: var(--shadow-md);
    transform: translateY(-2px);
    background: var(--bg-card-hover);
}
.reading-card-label {
    font-size: 0.72rem;
    text-transform: uppercase;
    letter-spacing: 0.12em;
    color: var(--accent);
    font-weight: 600;
    margin-bottom: 0.5rem;
}
.reading-card h3 {
    font-family: var(--font-serif);
    font-size: 1.25rem;
    font-weight: 500;
    margin-bottom: 0.5rem;
    color: var(--text);
}
.reading-card p {
    font-size: 0.9rem;
    color: var(--text-secondary);
    line-height: 1.6;
    margin-bottom: 0;
}
.reading-card-meta {
    font-size: 0.78rem;
    color: var(--text-muted);
    margin-top: 0.75rem;
}

/* ═══ CONCEPT NAV ═══ */
.concept-nav {
    max-width: var(--max-w);
    margin: 0 auto;
    padding: 2rem 2rem 0;
}
.concept-nav-label {
    font-size: 0.72rem;
    text-transform: uppercase;
    letter-spacing: 0.12em;
    color: var(--text-muted);
    margin-bottom: 0.75rem;
}
.concept-nav a {
    display: inline-block;
    padding: 0.5rem 1rem;
    border: 1px solid var(--border);
    border-radius: 6px;
    text-decoration: none;
    font-size: 0.9rem;
    color: var(--text-secondary);
    transition: all 0.2s;
    margin-right: 0.5rem;
    margin-bottom: 0.5rem;
}
.concept-nav a:hover {
    border-color: var(--accent);
    color: var(--text);
    background: var(--bg-card);
}

/* ═══ DIVIDER ═══ */
.section-divider {
    max-width: var(--max-w);
    margin: 0 auto;
    padding: 0 2rem;
}
.section-divider hr {
    border: none;
    border-top: 1px solid var(--border);
}

/* ═══ CTA ═══ */
.concept-cta {
    max-width: var(--max-w);
    margin: 0 auto;
    padding: 3rem 2rem 4rem;
    text-align: center;
}
.concept-cta p {
    font-size: 1rem;
    color: var(--text-secondary);
    margin-bottom: 1.5rem;
}
.concept-cta .btn {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    padding: 0.9rem 1.8rem;
    border-radius: 6px;
    text-decoration: none;
    font-size: 0.95rem;
    font-weight: 600;
    transition: all 0.2s;
    background: var(--accent);
    color: white;
}
.concept-cta .btn:hover {
    background: var(--accent-hover);
    transform: translateY(-1px);
}
.concept-cta .btn::after { content: ' →'; }
.concept-cta .btn-secondary {
    background: transparent;
    color: var(--text-secondary);
    border: 1px solid var(--border);
    margin-left: 0.75rem;
}
.concept-cta .btn-secondary::after { content: ''; }
.concept-cta .btn-secondary:hover {
    border-color: var(--border-hover);
    color: var(--text);
}

/* ═══ FOOTER ═══ */
.site-footer {
    text-align: center;
    padding: 3rem 2rem;
    border-top: 1px solid var(--border);
    font-size: 0.85rem;
    color: var(--text-muted);
    max-width: 1100px;
    margin: 0 auto;
}
.footer-brand { font-weight: 600; color: var(--text); margin-bottom: 0.75rem; }
.footer-links a { color: var(--text-secondary); text-decoration: none; margin: 0 0.4rem; }
.footer-links a:hover { color: var(--text); }
.footer-legal { margin-top: 0.75rem; font-size: 0.8rem; }
.footer-legal a { color: var(--text-muted); text-decoration: none; margin: 0 0.4rem; }
.footer-copy { margin-top: 1rem; }

/* ═══ CONTENT PAYWALL ═══ */
.concept-body--gated {
    position: relative;
}
.concept-body--gated::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    right: 0;
    height: 200px;
    background: linear-gradient(180deg, transparent 0%, var(--bg) 85%);
    pointer-events: none;
    z-index: 1;
}
.concept-gate {
    position: relative;
    z-index: 2;
    max-width: var(--max-w);
    margin: -2rem auto 0;
    padding: 0 2rem 4rem;
    text-align: center;
}
.concept-gate-card {
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: 16px;
    padding: 3rem 2.5rem;
    max-width: 480px;
    margin: 0 auto;
}
.concept-gate-card h3 {
    font-family: var(--font-serif);
    font-size: 1.4rem;
    font-weight: 400;
    margin-bottom: 0.75rem;
    color: var(--text);
}
.concept-gate-card p {
    font-size: 0.95rem;
    color: var(--text-secondary);
    line-height: 1.7;
    margin-bottom: 1.5rem;
}
.concept-gate-card .gate-btn {
    display: inline-block;
    padding: 0.85rem 2rem;
    border-radius: 8px;
    text-decoration: none;
    font-size: 0.95rem;
    font-weight: 600;
    background: var(--accent);
    color: white;
    border: none;
    cursor: pointer;
    transition: all 0.2s;
}
.concept-gate-card .gate-btn:hover {
    background: var(--accent-hover);
    transform: translateY(-1px);
}
.concept-gate-card .gate-signin {
    display: block;
    margin-top: 1rem;
    font-size: 0.82rem;
    color: var(--text-muted);
}
.concept-gate-card .gate-signin a {
    color: var(--accent);
    text-decoration: none;
}

/* ═══ RESPONSIVE ═══ */
@media (max-width: 640px) {
    .concept-hero { padding: 2rem 1.5rem 1.5rem; }
    .concept-body { padding: 0 1.5rem; }
    .reading-section { padding: 2rem 1.5rem 1rem; }
    .concept-cta { padding: 2rem 1.5rem 3rem; }
    .breadcrumb { padding: 0 1.5rem; }
    .compare-table { font-size: 0.82rem; }
    .compare-table th, .compare-table td { padding: 0.6rem 0.75rem; }
    .concept-cta .btn-secondary { margin-left: 0; margin-top: 0.75rem; display: inline-flex; }
    .concept-gate-card { padding: 2rem 1.5rem; }
}