/* ============================================================
   Authority World — the .lrn- shared reading layer
   Sprint 14 (M2a) · builds the K1-K12 contract fixed by
   /os/blueprints/authority-component-inventory.md and
   /os/blueprints/authority-reading-system.md, ratified by ADR-0005.

   One shared stylesheet, one namespace, no IIFE, no kinetic (§11.5).
   Every value below is drawn from tokens.css — no raw hex, no
   invented spacing scale. Loaded on /learn pages only, after
   tokens.css + style.css + shell.css.
   ============================================================ */

/* ---------------------------------------------------------------
   K1 — Reading layout (.lrn-article): the ~65ch long-form container
   --------------------------------------------------------------- */
.lrn-page {
    padding-top: 128px;
    padding-bottom: 96px;
}

.lrn-shell {
    display: grid;
    grid-template-columns: 1fr;
    gap: 48px;
    align-items: start;
}

.lrn-article {
    max-width: 65ch;
    color: var(--text-primary);
    font-size: 1.0625rem;
    line-height: 1.75;
}

.lrn-article h1 {
    font-size: clamp(2rem, 1.7rem + 1.2vw, 2.75rem);
    line-height: 1.15;
    letter-spacing: -0.02em;
    text-wrap: balance;
    margin: 0 0 20px;
    color: var(--text-primary);
}

.lrn-article h2 {
    font-size: 1.5rem;
    line-height: 1.3;
    letter-spacing: -0.01em;
    text-wrap: balance;
    margin: 56px 0 18px;
    color: var(--text-primary);
}

.lrn-article h3 {
    font-size: 1.15rem;
    line-height: 1.4;
    text-wrap: balance;
    margin: 36px 0 14px;
    color: var(--text-primary);
}

.lrn-article h4 {
    font-size: 1rem;
    font-weight: 600;
    margin: 28px 0 10px;
    color: var(--text-secondary);
}

.lrn-article p {
    margin: 0 0 20px;
    color: var(--text-secondary);
}

.lrn-article ul,
.lrn-article ol {
    margin: 0 0 20px;
    padding-left: 1.3em;
    color: var(--text-secondary);
}

.lrn-article li {
    margin-bottom: 8px;
}

.lrn-article a {
    color: var(--accent-text);
    text-underline-offset: 3px;
    text-decoration-color: var(--border-hover);
}

.lrn-article a:hover {
    text-decoration-color: var(--accent-text);
}

.lrn-article strong {
    color: var(--text-primary);
    font-weight: 600;
}

.lrn-article figure {
    margin: 32px 0;
}

.lrn-article figcaption {
    font-size: 0.85rem;
    color: var(--text-muted);
    margin-top: 8px;
}

/* Short variant — glossary terms (K1, short) */
.lrn-article--short {
    max-width: 60ch;
}

/* Answer lede — the answer-first opening block */
.lrn-lede {
    font-size: 1.2rem;
    line-height: 1.6;
    color: var(--text-primary);
    padding: 20px 24px;
    margin: 0 0 40px;
    background: var(--surface-panel);
    border-left: 3px solid var(--accent);
    border-radius: 0 var(--radius-md) var(--radius-md) 0;
}

.lrn-lede p {
    margin: 0;
    color: var(--text-primary);
}

.lrn-lede p + p {
    margin-top: 12px;
}

/* ---------------------------------------------------------------
   K2 — Breadcrumb (.lrn-crumb)
   --------------------------------------------------------------- */
.lrn-crumb {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    gap: 6px;
    font-size: 0.85rem;
    color: var(--text-muted);
    margin-bottom: 28px;
}

.lrn-crumb a {
    color: var(--text-muted);
    text-decoration: none;
}

.lrn-crumb a:hover {
    color: var(--accent-text);
}

.lrn-crumb span[aria-current] {
    color: var(--text-secondary);
}

.lrn-crumb .lrn-crumb-sep {
    color: var(--border-hover);
}

/* ---------------------------------------------------------------
   K3 — Cluster side-rail (.lrn-rail)
   --------------------------------------------------------------- */
.lrn-rail {
    font-size: 0.9rem;
}

.lrn-rail-head {
    font-size: 0.75rem;
    font-weight: 600;
    letter-spacing: 0.04em;
    text-transform: uppercase;
    color: var(--text-muted);
    margin: 0 0 12px;
}

.lrn-rail-list {
    list-style: none;
    margin: 0;
    padding: 0;
    display: flex;
    flex-direction: column;
    gap: 2px;
    border-left: 1px solid var(--border);
}

.lrn-rail-list a {
    display: block;
    padding: 8px 0 8px 16px;
    margin-left: -1px;
    border-left: 2px solid transparent;
    color: var(--text-secondary);
    text-decoration: none;
    line-height: 1.4;
}

.lrn-rail-list a:hover {
    color: var(--text-primary);
}

.lrn-rail-list a[aria-current] {
    color: var(--text-primary);
    font-weight: 600;
    border-left-color: var(--accent);
}

.lrn-rail-list .lrn-rail-sub {
    padding-left: 28px;
    font-size: 0.85rem;
}

/* ---------------------------------------------------------------
   K4 — Definition block (.lrn-def)
   --------------------------------------------------------------- */
.lrn-def {
    margin: 0 0 32px;
    padding: 20px 24px;
    background: var(--bg-elevated);
    border: 1px solid var(--border);
    border-left: 3px solid var(--accent);
    border-radius: var(--radius-md);
}

.lrn-def dt {
    font-size: 0.75rem;
    font-weight: 600;
    letter-spacing: 0.04em;
    text-transform: uppercase;
    color: var(--accent-text);
    margin-bottom: 8px;
}

.lrn-def dd {
    margin: 0;
    font-size: 1.05rem;
    line-height: 1.6;
    color: var(--text-primary);
}

/* ---------------------------------------------------------------
   K5 — Stat-line (.lrn-stat)
   --------------------------------------------------------------- */
.lrn-stat {
    display: flex;
    flex-wrap: wrap;
    align-items: baseline;
    gap: 8px 14px;
    margin: 0 0 28px;
    padding: 16px 20px;
    background: var(--surface-panel);
    border-radius: var(--radius-md);
}

.lrn-stat-value {
    font-variant-numeric: tabular-nums;
    font-size: 1.4rem;
    font-weight: 700;
    color: var(--accent-text);
    white-space: nowrap;
}

.lrn-stat-meaning {
    color: var(--text-secondary);
    font-size: 0.95rem;
}

.lrn-stat-proof {
    flex-basis: 100%;
    font-size: 0.8rem;
}

.lrn-stat-proof a {
    color: var(--text-muted);
}

.lrn-stat-proof a:hover {
    color: var(--accent-text);
}

/* ---------------------------------------------------------------
   K6 — Callout (.lrn-note)
   --------------------------------------------------------------- */
.lrn-note {
    display: flex;
    gap: 12px;
    margin: 0 0 28px;
    padding: 16px 20px;
    border-radius: var(--radius-md);
    background: var(--surface-panel);
    border: 1px solid var(--border);
    font-size: 0.95rem;
    color: var(--text-secondary);
}

.lrn-note-icon {
    flex: none;
    color: var(--accent-text);
    margin-top: 2px;
}

.lrn-note--caution {
    border-color: rgba(239, 68, 68, 0.25);
}

.lrn-note--caution .lrn-note-icon {
    color: var(--danger);
}

.lrn-note--key {
    border-color: rgba(16, 185, 129, 0.25);
}

.lrn-note--key .lrn-note-icon {
    color: var(--success);
}

/* ---------------------------------------------------------------
   K7 — Comparison table (.lrn-cmp)
   --------------------------------------------------------------- */
.lrn-cmp-wrap {
    overflow-x: auto;
    margin: 0 0 32px;
    border: 1px solid var(--border);
    border-radius: var(--radius-md);
}

.lrn-cmp {
    width: 100%;
    border-collapse: collapse;
    font-size: 0.9rem;
    min-width: 480px;
}

.lrn-cmp caption {
    caption-side: top;
    text-align: left;
    padding: 14px 16px 0;
    font-size: 0.8rem;
    color: var(--text-muted);
}

.lrn-cmp th,
.lrn-cmp td {
    text-align: left;
    padding: 12px 16px;
    border-bottom: 1px solid var(--border-hairline);
    font-variant-numeric: tabular-nums;
}

.lrn-cmp th {
    font-weight: 600;
    color: var(--text-primary);
    background: var(--surface-panel);
}

.lrn-cmp td {
    color: var(--text-secondary);
}

.lrn-cmp tr:last-child td {
    border-bottom: none;
}

/* ---------------------------------------------------------------
   K8 — Code / config block (.lrn-code)
   --------------------------------------------------------------- */
.lrn-code {
    display: block;
    overflow-x: auto;
    margin: 0 0 28px;
    padding: 16px 20px;
    background: var(--bg-elevated);
    border: 1px solid var(--border);
    border-radius: var(--radius-md);
    font-family: ui-monospace, "SF Mono", Consolas, monospace;
    font-size: 0.85rem;
    line-height: 1.6;
    color: var(--text-primary);
    white-space: pre;
}

/* ---------------------------------------------------------------
   K9 — FAQ pair (.lrn-faq) — native <details>
   --------------------------------------------------------------- */
.lrn-faq {
    border-top: 1px solid var(--border);
}

.lrn-faq-item {
    border-bottom: 1px solid var(--border);
}

.lrn-faq-item summary {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 16px;
    padding: 16px 4px;
    cursor: pointer;
    font-weight: 600;
    color: var(--text-primary);
    list-style: none;
}

.lrn-faq-item summary::-webkit-details-marker {
    display: none;
}

.lrn-faq-item summary::after {
    content: '+';
    flex: none;
    color: var(--text-muted);
    font-size: 1.2rem;
    line-height: 1;
}

.lrn-faq-item[open] summary::after {
    content: '\2212';
}

.lrn-faq-item p {
    margin: 0 0 16px;
    padding: 0 4px;
    color: var(--text-secondary);
}

/* ---------------------------------------------------------------
   K10 — Seam callout (.lrn-seam) — "See it run" bridge
   --------------------------------------------------------------- */
.lrn-seam {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    justify-content: space-between;
    gap: 16px;
    margin: 48px 0 8px;
    padding: 24px 28px;
    border-radius: var(--radius-lg);
    background: var(--gradient-accent);
}

.lrn-seam-text {
    color: #fff;
    max-width: 46ch;
}

.lrn-seam-eyebrow {
    display: block;
    font-size: 0.75rem;
    font-weight: 600;
    letter-spacing: 0.04em;
    text-transform: uppercase;
    opacity: 0.85;
    margin-bottom: 4px;
}

.lrn-seam-line {
    font-size: 1.05rem;
    font-weight: 500;
    line-height: 1.4;
}

.lrn-seam-link {
    flex: none;
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 12px 22px;
    border-radius: var(--radius-sm);
    background: #fff;
    color: var(--text-primary);
    font-weight: 600;
    font-size: 0.95rem;
    text-decoration: none;
    white-space: nowrap;
}

.lrn-seam-link:hover {
    opacity: 0.9;
}

/* ---------------------------------------------------------------
   K11 — "Last verified" stamp (.lrn-verified)
   --------------------------------------------------------------- */
.lrn-verified {
    display: flex;
    align-items: center;
    gap: 8px;
    margin-top: 40px;
    padding-top: 20px;
    border-top: 1px solid var(--border-hairline);
    font-size: 0.8rem;
    color: var(--text-muted);
}

.lrn-verified-dot {
    width: 6px;
    height: 6px;
    border-radius: 50%;
    background: var(--success);
    flex: none;
}

/* ---------------------------------------------------------------
   K12 — Resource card (.lrn-resource)
   --------------------------------------------------------------- */
.lrn-resource-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
    gap: 20px;
}

.lrn-resource {
    padding: 22px;
    border-radius: var(--radius-md);
    border: 1px solid var(--border);
    background: var(--bg-elevated);
}

.lrn-resource-icon {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 40px;
    height: 40px;
    border-radius: var(--radius-sm);
    background: var(--accent-soft);
    color: var(--accent-text);
    margin-bottom: 14px;
}

.lrn-resource h3 {
    font-size: 1rem;
    margin: 0 0 6px;
    color: var(--text-primary);
}

.lrn-resource p {
    font-size: 0.88rem;
    color: var(--text-secondary);
    margin: 0;
}

.lrn-resource-status {
    display: inline-block;
    margin-top: 12px;
    font-size: 0.75rem;
    font-weight: 600;
    letter-spacing: 0.03em;
    text-transform: uppercase;
    color: var(--text-muted);
}

/* ---------------------------------------------------------------
   K1 index variant — hub / glossary / faq / resources index pages
   (a composition of K1, not a new component — knowledge-taxonomy §3)
   --------------------------------------------------------------- */
.lrn-hero {
    max-width: 62ch;
    margin: 0 0 56px;
}

.lrn-hero-eyebrow {
    display: inline-block;
    font-size: 0.78rem;
    font-weight: 600;
    letter-spacing: 0.05em;
    text-transform: uppercase;
    color: var(--accent-text);
    margin-bottom: 14px;
}

.lrn-hero h1 {
    font-size: clamp(2.1rem, 1.8rem + 1.4vw, 2.9rem);
    line-height: 1.15;
    letter-spacing: -0.02em;
    text-wrap: balance;
    margin: 0 0 18px;
    color: var(--text-primary);
}

.lrn-hero p {
    font-size: 1.1rem;
    line-height: 1.65;
    color: var(--text-secondary);
    margin: 0;
}

.lrn-section-head {
    display: flex;
    align-items: baseline;
    justify-content: space-between;
    gap: 16px;
    margin: 0 0 24px;
}

.lrn-section-head h2 {
    font-size: 1.35rem;
    color: var(--text-primary);
    margin: 0;
}

.lrn-section-note {
    font-size: 0.85rem;
    color: var(--text-muted);
}

.lrn-cluster-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
    gap: 20px;
    margin-bottom: 56px;
}

.lrn-cluster-card {
    padding: 24px;
    border-radius: var(--radius-lg);
    border: 1px solid var(--border);
    background: var(--bg-elevated);
    text-decoration: none;
    display: block;
    transition: border-color 0.2s ease, transform 0.2s ease;
}

.lrn-cluster-card:hover {
    border-color: var(--border-hover);
    transform: translateY(-2px);
}

.lrn-cluster-card h3 {
    font-size: 1.05rem;
    color: var(--text-primary);
    margin: 0 0 8px;
}

.lrn-cluster-card p {
    font-size: 0.88rem;
    color: var(--text-secondary);
    margin: 0;
}

.lrn-cluster-card--reserved {
    opacity: 0.55;
    cursor: default;
}

.lrn-cluster-card--reserved:hover {
    transform: none;
    border-color: var(--border);
}

.lrn-tag {
    display: inline-block;
    font-size: 0.7rem;
    font-weight: 600;
    letter-spacing: 0.03em;
    text-transform: uppercase;
    color: var(--text-muted);
    background: var(--surface-panel);
    padding: 3px 9px;
    border-radius: 999px;
    margin-bottom: 12px;
}

.lrn-tag--live {
    color: var(--success);
}

.lrn-index-list {
    list-style: none;
    margin: 0 0 56px;
    padding: 0;
    display: flex;
    flex-direction: column;
}

.lrn-index-list li {
    border-bottom: 1px solid var(--border-hairline);
}

.lrn-index-list a {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 16px;
    padding: 16px 4px;
    color: var(--text-primary);
    text-decoration: none;
    font-weight: 500;
}

.lrn-index-list a:hover {
    color: var(--accent-text);
}

.lrn-index-list .lrn-index-arrow {
    color: var(--text-muted);
    flex: none;
}

/* ---------------------------------------------------------------
   Wide-viewport layout: side-rail sibling column (breakpoint)
   --------------------------------------------------------------- */
@media (min-width: 960px) {
    .lrn-shell--with-rail {
        grid-template-columns: minmax(0, 1fr) 240px;
        gap: 64px;
    }

    .lrn-rail {
        position: sticky;
        top: 120px;
    }
}