/* ============================================================
   LESSON — the 9-Layer Protocol as a page
   Loaded after base.css (+ viz.css). Every lesson page uses this
   exact skeleton, so all ~83 of them stay consistent.
   ============================================================ */

/* ---------- Reading progress bar ---------- */
.read-bar {
  position: fixed; inset: 0 0 auto 0; height: 3px; z-index: 110;
  background: transparent; pointer-events: none;
}
.read-bar i {
  display: block; height: 100%; width: 0%;
  background: linear-gradient(90deg, var(--accent), var(--gold));
  transition: width .1s linear;
}

/* ============================================================
   SHELL
   ============================================================ */
.lesson-shell {
  --accent: var(--gold);
  max-width: 1440px; margin-inline: auto;
  padding: 116px var(--gutter) 0;
  display: grid;
  grid-template-columns: 250px minmax(0, 1fr) 210px;
  gap: clamp(28px, 3.5vw, 56px);
  align-items: start;
}

/* ---------- Left: module lesson list ---------- */
.lesson-aside {
  position: sticky; top: 96px;
  max-height: calc(100vh - 120px);
  overflow-y: auto;
  padding-bottom: 20px;
  scrollbar-width: thin;
}
.aside-mod {
  display: flex; align-items: center; gap: 11px;
  padding-bottom: 14px; margin-bottom: 14px;
  border-bottom: 1px solid var(--border);
}
.aside-mod .badge {
  width: 34px; height: 34px; border-radius: 10px; flex: none;
  display: grid; place-items: center; color: var(--accent-ink, var(--accent));
  background: color-mix(in srgb, var(--accent) 14%, transparent);
  border: 1px solid color-mix(in srgb, var(--accent) 36%, transparent);
}
.aside-mod .badge svg { width: 18px; height: 18px; }
.aside-mod strong { font-family: var(--font-display); font-size: .95rem; line-height: 1.25; display: block; }
.aside-mod span {
  font-family: var(--font-mono); font-size: .66rem;
  letter-spacing: .12em; color: var(--text-faint); text-transform: uppercase;
}
.aside-list { display: flex; flex-direction: column; gap: 1px; }
.aside-list a, .aside-list span.soon {
  display: flex; gap: 9px; align-items: baseline;
  padding: 8px 10px; border-radius: 9px;
  font-size: .88rem; line-height: 1.4; color: var(--text-muted);
  transition: background .2s, color .2s;
}
.aside-list a:hover { background: var(--grid-line); color: var(--text); }
.aside-list a.current {
  background: color-mix(in srgb, var(--accent) 12%, transparent);
  color: var(--text); font-weight: 600;
}
.aside-list .n {
  font-family: var(--font-mono); font-size: .7rem; color: var(--text-faint);
  flex: none; min-width: 17px; font-variant-numeric: tabular-nums;
}
.aside-list a.current .n { color: var(--accent); }
.aside-list a.done .n::before { content: "✓"; color: var(--accent); }
.aside-list a.done .n { font-size: .78rem; }
.aside-list span.soon { opacity: .45; cursor: default; }
.aside-list span.soon em { margin-left: auto; color: var(--text-subtle); font: 600 .62rem var(--font-mono); letter-spacing: .08em; text-transform: uppercase; }

/* ---------- Right: on-page TOC ---------- */
.lesson-toc { position: sticky; top: 96px; }
.lesson-toc h5 {
  font-family: var(--font-mono); font-size: .66rem; font-weight: 600;
  letter-spacing: .16em; text-transform: uppercase; color: var(--text-faint);
  margin-bottom: 12px;
}
.lesson-toc a {
  display: block; padding: 6px 0 6px 13px;
  border-left: 2px solid var(--border);
  font-size: .84rem; line-height: 1.4; color: var(--text-faint);
  transition: color .2s, border-color .2s;
}
.lesson-toc a:hover { color: var(--text-muted); }
.lesson-toc a.active { color: var(--accent); border-left-color: var(--accent); font-weight: 600; }

/* ============================================================
   ARTICLE
   ============================================================ */
.lesson-main { min-width: 0; padding-bottom: 60px; }

.breadcrumb {
  display: flex; align-items: center; flex-wrap: wrap; gap: 8px;
  font-family: var(--font-mono); font-size: .74rem;
  color: var(--text-faint); margin-bottom: 22px;
}
.breadcrumb a { transition: color .2s; }
.breadcrumb a:hover { color: var(--accent); }
.breadcrumb .sep { opacity: .5; }

.lesson-head { margin-bottom: clamp(30px, 4vw, 44px); }
.lesson-head .eyebrow { color: var(--accent-ink, var(--accent)); }
[data-theme="dark"] .lesson-head .eyebrow { color: var(--accent-ink, var(--accent)); }
.lesson-head .eyebrow::before { background: var(--accent); }
.lesson-head h1 {
  font-size: clamp(2rem, 4.4vw, 3.1rem);
  letter-spacing: -.032em; margin-top: 16px;
}
.lesson-meta {
  display: flex; flex-wrap: wrap; gap: 10px 18px; align-items: center;
  margin-top: 20px; padding-top: 18px; border-top: 1px solid var(--border);
  font-family: var(--font-mono); font-size: .76rem; color: var(--text-faint);
}
.lesson-meta .dot { width: 3px; height: 3px; border-radius: 50%; background: var(--border-strong); }

/* ---------- Prose ---------- */
.prose { max-width: 68ch; font-size: 1.125rem; }
.prose > p { margin-bottom: 1.15em; color: var(--text); line-height: 1.7; }
.prose > p.lead { font-size: 1.14rem; color: var(--text-muted); }
.prose strong { font-weight: 600; }
.prose em { font-style: italic; }
.prose a:not(.btn) {
  color: var(--accent-ink, var(--accent)); text-decoration: underline;
  text-decoration-thickness: 1px; text-underline-offset: 3px;
}
.prose ul, .prose ol { margin: 0 0 1.15em 0; padding-left: 1.3em; }
.prose ul { list-style: disc; }
.prose ol { list-style: decimal; }
.prose li { margin-bottom: .45em; line-height: 1.65; padding-left: .2em; }
.prose li::marker { color: var(--accent); }
.prose code {
  font-family: var(--font-mono); font-size: .87em;
  background: var(--grid-line); padding: 2px 6px; border-radius: 6px;
  border: 1px solid var(--border);
}

/* ---------- Layer section headers ---------- */
.layer-sec { margin-top: clamp(46px, 6vw, 72px); scroll-margin-top: 96px; }
.layer-sec > h2 {
  font-size: clamp(1.5rem, 2.8vw, 2rem);
  letter-spacing: -.028em; margin-bottom: 20px;
  padding-top: 14px; border-top: 1px solid var(--border);
  position: relative;
}
.layer-sec > h2::before {
  content: attr(data-layer);
  display: block;
  font-family: var(--font-mono); font-size: .68rem; font-weight: 600;
  letter-spacing: .2em; text-transform: uppercase;
  color: var(--accent-ink, var(--accent)); margin-bottom: 12px;
}
.prose-subhead { font-size: 1.15rem; margin-top: 32px; margin-bottom: 12px; }

/* ============================================================
   LAYER 1 — the hook
   ============================================================ */
.lesson-hook {
  position: relative;
  padding: 24px 26px 24px 30px;
  border-radius: var(--radius);
  background: color-mix(in srgb, var(--accent) 7%, var(--surface));
  border: 1px solid color-mix(in srgb, var(--accent) 26%, transparent);
  margin-bottom: 8px;
}
.lesson-hook::before {
  content: ""; position: absolute; inset: 14px auto 14px 0; width: 3px;
  border-radius: 999px; background: var(--accent);
}
.lesson-hook p { margin: 0; line-height: 1.7; }
.lesson-hook p + p { margin-top: .8em; }

/* ============================================================
   LAYER 2 — intuition + analogy
   ============================================================ */
.intuition-card {
  background: var(--surface); border: 1px solid var(--border);
  border-radius: var(--radius-lg); padding: 26px 28px;
  box-shadow: var(--shadow-card);
}
.intuition-card .tag {
  font-family: var(--font-mono); font-size: .68rem; font-weight: 600;
  letter-spacing: .16em; text-transform: uppercase; color: var(--accent);
  display: block; margin-bottom: 9px;
}
.intuition-card p { margin: 0; line-height: 1.7; }
.intuition-card .analogy {
  margin-top: 22px; padding-top: 20px; border-top: 1px dashed var(--border);
}

/* ============================================================
   LAYER 4 — math
   ============================================================ */
.math-block {
  background: var(--surface-2); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 24px 26px; margin-block: 24px;
  overflow-x: auto;
}
.math-block .eq {
  font-family: var(--font-mono); font-size: 1.1rem;
  text-align: center; padding: 8px 0 14px; color: var(--text);
  letter-spacing: .01em;
}
.math-block .in-words {
  font-size: .95rem; color: var(--text-muted);
  padding-top: 14px; border-top: 1px dashed var(--border);
  line-height: 1.6;
}
.math-block .in-words b { color: var(--accent); font-weight: 600; }

.symbol-table { width: 100%; border-collapse: collapse; margin-top: 18px; font-size: .93rem; }
.symbol-table th {
  text-align: left; font-family: var(--font-mono); font-size: .66rem;
  letter-spacing: .14em; text-transform: uppercase; color: var(--text-faint);
  padding-bottom: 9px; border-bottom: 1px solid var(--border); font-weight: 600;
}
.symbol-table td { padding: 10px 14px 10px 0; border-bottom: 1px solid var(--border); vertical-align: top; }
.symbol-table td:first-child {
  font-family: var(--font-mono); font-weight: 600; color: var(--accent);
  white-space: nowrap; width: 1%;
}
.symbol-table td:last-child { color: var(--text-muted); }
.symbol-table tr:last-child td { border-bottom: none; }

/* ============================================================
   LAYERS 5 & 6 — code
   ============================================================ */
.code-block { margin-block: 24px; border-radius: var(--radius); overflow: hidden; border: 1px solid var(--border); }
.code-head {
  display: flex; align-items: center; justify-content: space-between; gap: 14px;
  padding: 11px 16px;
  background: var(--surface-2); border-bottom: 1px solid var(--border);
}
.code-title {
  font-family: var(--font-mono); font-size: .72rem; font-weight: 600;
  letter-spacing: .1em; text-transform: uppercase; color: var(--text-muted);
  display: flex; align-items: center; gap: 9px;
}
.code-title::before {
  content: ""; width: 7px; height: 7px; border-radius: 50%;
  background: var(--accent); flex: none;
}
.code-copy {
  font-family: var(--font-mono); font-size: .7rem; font-weight: 600;
  letter-spacing: .08em; text-transform: uppercase;
  color: var(--text-faint); border: 1px solid var(--border);
  border-radius: 7px; padding: 5px 11px; transition: .2s; white-space: nowrap;
}
.code-copy:hover { color: var(--accent); border-color: var(--accent); }
.code-copy.copied { color: var(--accent); border-color: var(--accent); }

.code-block pre {
  margin: 0; padding: 20px 22px; overflow-x: auto;
  background: var(--code-bg); color: var(--code-text);
  font-family: var(--font-mono); font-size: .86rem; line-height: 1.75;
  tab-size: 4;
}
.code-block pre code { font: inherit; background: none; border: none; padding: 0; }

/* Syntax tokens — js/highlight.js. Tuned against the navy code
   background, which is the same in both themes. */
.tk-kw  { color: #E8A5C8; }
.tk-str { color: #A8D8A0; }
.tk-num { color: #E3C58A; }
.tk-com { color: #7C8AA8; font-style: italic; }
.tk-bi  { color: #86C7E8; }
.tk-fn  { color: #D3AE6C; }

/* Expected output block, attached below the code */
.code-out {
  padding: 14px 22px;
  background: var(--surface-2); border-top: 1px solid var(--border);
  font-family: var(--font-mono); font-size: .8rem; line-height: 1.7;
  color: var(--text-muted); white-space: pre-wrap; overflow-x: auto;
}
.code-out::before {
  content: "Output";
  display: block; font-size: .64rem; letter-spacing: .16em; text-transform: uppercase;
  color: var(--text-faint); margin-bottom: 7px; font-weight: 600;
}

/* ============================================================
   LAYER 7 — decision table
   ============================================================ */
.decision-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 18px; margin-block: 22px; }
.decision-col {
  border: 1px solid var(--border); border-radius: var(--radius);
  padding: 22px 24px; background: var(--surface);
}
.decision-col h4 {
  font-size: .95rem; display: flex; align-items: center; gap: 9px; margin-bottom: 14px;
}
.decision-col h4::before {
  font-family: var(--font-mono); font-size: 1.05rem; line-height: 1;
}
.decision-col.use { border-color: color-mix(in srgb, #2E8B57 32%, transparent); }
.decision-col.use h4 { color: #2E8B57; }
.decision-col.use h4::before { content: "✓"; }
.decision-col.avoid { border-color: color-mix(in srgb, #C0453C 32%, transparent); }
.decision-col.avoid h4 { color: #C0453C; }
.decision-col.avoid h4::before { content: "✕"; }
[data-theme="dark"] .decision-col.use h4 { color: #5FCB8B; }
[data-theme="dark"] .decision-col.avoid h4 { color: #EE7B72; }
.decision-col ul { margin: 0; padding-left: 1.1em; list-style: disc; }
.decision-col li { font-size: .93rem; color: var(--text-muted); margin-bottom: .55em; line-height: 1.6; }

/* ============================================================
   LAYER 8 — pitfalls
   ============================================================ */
.pitfall-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); gap: 16px; margin-block: 22px; }
.pitfall {
  background: var(--surface); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 20px 22px;
  border-left: 3px solid color-mix(in srgb, #C0453C 55%, transparent);
}
.pitfall h4 { font-size: .98rem; margin-bottom: 12px; }
.pitfall dl { margin: 0; font-size: .91rem; line-height: 1.6; }
.pitfall dt {
  font-family: var(--font-mono); font-size: .64rem; font-weight: 600;
  letter-spacing: .14em; text-transform: uppercase; color: var(--text-faint);
  margin-top: 11px;
}
.pitfall dt:first-child { margin-top: 0; }
.pitfall dd { margin: 4px 0 0; color: var(--text-muted); }
.pitfall dd code {
  font-family: var(--font-mono); font-size: .87em;
  background: var(--grid-line); padding: 1px 5px; border-radius: 5px;
}

/* ============================================================
   LAYER 9 — check yourself + connections
   ============================================================ */
.connections { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; margin-block: 22px; }
.connection {
  border: 1px solid var(--border); border-radius: var(--radius);
  padding: 18px 20px; background: var(--surface);
}
.connection span {
  font-family: var(--font-mono); font-size: .64rem; font-weight: 600;
  letter-spacing: .16em; text-transform: uppercase; color: var(--text-faint);
  display: block; margin-bottom: 7px;
}
.connection strong { font-family: var(--font-display); font-size: 1rem; font-weight: 600; }
.connection a { color: var(--accent); }

.qa { margin-block: 20px; display: flex; flex-direction: column; gap: 12px; }
.qa details {
  border: 1px solid var(--border); border-radius: var(--radius);
  background: var(--surface); overflow: hidden;
}
.qa summary {
  padding: 15px 20px; cursor: pointer; font-weight: 600; font-size: .96rem;
  list-style: none; display: flex; align-items: center; gap: 11px;
  transition: background .2s;
}
.qa summary::-webkit-details-marker { display: none; }
.qa summary::before {
  content: "+"; font-family: var(--font-mono); color: var(--accent);
  font-size: 1.1rem; line-height: 1; flex: none; transition: transform .25s var(--ease-out);
}
.qa details[open] summary::before { transform: rotate(45deg); }
.qa summary:hover { background: var(--grid-line); }
.qa .ans { padding: 0 20px 17px 44px; color: var(--text-muted); font-size: .94rem; line-height: 1.65; }
.qa .tag {
  margin-left: auto; font-family: var(--font-mono); font-size: .62rem; font-weight: 600;
  letter-spacing: .1em; text-transform: uppercase; color: var(--text-faint);
  border: 1px solid var(--border); border-radius: 6px; padding: 3px 8px; flex: none;
}

.check-yourself {
  margin-top: 30px;
  padding: 26px 28px; border-radius: var(--radius-lg);
  background: linear-gradient(150deg, color-mix(in srgb, var(--accent) 12%, var(--surface)), var(--surface));
  border: 1px solid color-mix(in srgb, var(--accent) 32%, transparent);
}
.check-yourself span {
  font-family: var(--font-mono); font-size: .68rem; font-weight: 600;
  letter-spacing: .16em; text-transform: uppercase; color: var(--accent);
  display: block; margin-bottom: 11px;
}
.check-yourself p { font-size: 1.08rem; line-height: 1.6; margin: 0; font-weight: 500; }
.check-yourself small { display: block; margin-top: 12px; color: var(--text-faint); font-size: .85rem; }

/* ============================================================
   COMPLETE + PREV/NEXT
   ============================================================ */
.lesson-complete {
  display: flex; align-items: center; gap: 16px; flex-wrap: wrap;
  margin-top: 44px; padding: 22px 24px;
  border: 1px dashed var(--border-strong); border-radius: var(--radius);
}
.lesson-complete p { margin: 0; color: var(--text-muted); font-size: .95rem; flex: 1; min-width: 200px; }
.mark-done {
  display: inline-flex; align-items: center; gap: 10px;
  font-family: var(--font-mono); font-size: .78rem; font-weight: 600;
  letter-spacing: .06em; text-transform: uppercase;
  padding: 11px 20px; border-radius: 999px;
  border: 1px solid var(--border-strong); color: var(--text);
  transition: .25s; white-space: nowrap;
}
.mark-done:hover { border-color: var(--accent); color: var(--accent); }
.mark-done.is-done {
  background: var(--accent); border-color: var(--accent); color: var(--navy-deep);
}
.mark-done .tick { font-size: .95rem; }

.lesson-nav {
  display: grid; grid-template-columns: 1fr 1fr; gap: 16px;
  margin-top: 26px;
}
.lesson-nav a {
  border: 1px solid var(--border); border-radius: var(--radius);
  padding: 18px 22px; background: var(--surface);
  transition: border-color .25s, transform .25s var(--ease-out);
}
.lesson-nav a:hover { border-color: var(--accent); transform: translateY(-2px); }
.lesson-nav span {
  font-family: var(--font-mono); font-size: .66rem; font-weight: 600;
  letter-spacing: .14em; text-transform: uppercase; color: var(--text-faint);
  display: block; margin-bottom: 7px;
}
.lesson-nav strong { font-family: var(--font-display); font-size: 1rem; font-weight: 600; line-height: 1.3; display: block; }
.lesson-nav .next { text-align: right; }
.lesson-nav .spacer { border: none; background: none; }

/* ============================================================
   RESPONSIVE
   ============================================================ */
@media (max-width: 1280px) {
  .lesson-shell { grid-template-columns: 235px minmax(0, 1fr); }
  .lesson-toc { display: none; }
}
@media (max-width: 1000px) {
  .lesson-shell { grid-template-columns: minmax(0, 1fr); padding-top: 96px; }
  .lesson-aside { display: none; }
  .lesson-mobile-nav { display: block; margin: 14px 0 24px; border: 1px solid var(--border); border-radius: var(--radius-sm); background: var(--surface); overflow: hidden; }
  .lesson-mobile-nav summary { display: grid; grid-template-columns: 1fr auto; align-items: center; gap: 8px; min-height: 54px; padding: 12px 16px; cursor: pointer; list-style: none; }
  .lesson-mobile-nav summary::-webkit-details-marker { display: none; }
  .lesson-mobile-nav summary::after { content: "+"; grid-row: 1 / span 2; grid-column: 2; color: var(--accent-ink, var(--accent)); font: 500 1.3rem/1 var(--font-mono); }
  .lesson-mobile-nav[open] summary::after { content: "−"; }
  .lesson-mobile-nav summary span { color: var(--text-subtle); font: 600 .66rem var(--font-mono); letter-spacing: .08em; text-transform: uppercase; }
  .lesson-mobile-nav summary strong { font: 600 .95rem/1.3 var(--font-display); }
  .mobile-module-list, .mobile-outline { display: flex; flex-direction: column; padding: 8px 12px 14px; border-top: 1px solid var(--border); }
  .mobile-module-list a, .mobile-module-list .soon, .mobile-outline a { display: flex; gap: 9px; align-items: baseline; min-height: 38px; padding: 8px; border-radius: 8px; color: var(--text-muted); font-size: .9rem; }
  .mobile-module-list a.current { color: var(--text); font-weight: 600; background: color-mix(in srgb, var(--accent) 10%, transparent); }
  .mobile-module-list .n { color: var(--accent-ink, var(--accent)); font: 600 .68rem var(--font-mono); min-width: 22px; }
  .mobile-module-list .soon { opacity: .55; }
  .mobile-module-list em { margin-left: auto; color: var(--text-subtle); font: 600 .62rem var(--font-mono); letter-spacing: .08em; text-transform: uppercase; }
  .mobile-outline { padding-top: 14px; }
  .mobile-outline > span { margin: 0 8px 5px; color: var(--text-subtle); font: 600 .65rem var(--font-mono); letter-spacing: .12em; text-transform: uppercase; }
  .mobile-outline a { min-height: 34px; padding-block: 6px; }
}
@media (max-width: 700px) {
  .decision-grid, .connections, .lesson-nav { grid-template-columns: 1fr; }
  .lesson-nav .next { text-align: left; }
  .code-block pre { padding: 16px; font-size: .8rem; }
  .lesson-hook, .intuition-card, .math-block, .check-yourself { padding: 20px; }
  .prose { font-size: 1rem; }
  .prose > p { line-height: 1.68; }
}
@media (min-width: 1001px) { .lesson-mobile-nav { display: none; } }