/* Shared lesson stylesheet — parchment design system */
:root {
  --parchment: #f5f4ed;
  --ivory: #faf9f5;
  --near-black: #141413;
  --charcoal: #4d4c48;
  --olive: #5e5d59;
  --stone: #87867f;
  --brand: #1B365D;
  --accent: #9A5A32;
  --green: #3F6B52;
  --border: #e8e6dc;
  --soft-blue: #E4ECF5;
  --soft-warn: #F2E7D8;
  --serif: Georgia, "Times New Roman", serif;
  --mono: "JetBrains Mono", "SF Mono", Consolas, monospace;
}

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

html { background: var(--parchment); }
body {
  background: var(--parchment);
  color: var(--near-black);
  font-family: var(--serif);
  font-size: 16px;
  line-height: 1.65;
  max-width: 700px;
  margin: 0 auto;
  padding: 48px 32px 80px;
}

/* ── Header ── */
.lesson-eyebrow {
  font-family: var(--mono);
  font-size: 11px;
  letter-spacing: 2px;
  text-transform: uppercase;
  color: var(--brand);
  margin-bottom: 10px;
}
h1 {
  font-size: 2rem;
  font-weight: 400;
  line-height: 1.2;
  margin-bottom: 8px;
  color: var(--near-black);
}
.lesson-sub {
  font-size: 1.05rem;
  color: var(--olive);
  margin-bottom: 40px;
  border-bottom: 1px solid var(--border);
  padding-bottom: 20px;
}
.lesson-hero {
  margin: 0 0 28px;
}
.lesson-hero img {
  display: block;
  width: 100%;
  aspect-ratio: 2 / 1;
  object-fit: cover;
  border: 1px solid var(--border);
  border-radius: 6px;
}

/* ── Typography ── */
h2 {
  font-size: 1.25rem;
  font-weight: 400;
  margin: 40px 0 12px;
  border-left: 3px solid var(--brand);
  padding-left: 12px;
  color: var(--near-black);
}
h3 {
  font-size: 1rem;
  font-weight: 600;
  margin: 28px 0 8px;
  color: var(--charcoal);
}
p { margin-bottom: 16px; }
strong { font-weight: 600; }
.lead {
  font-size: 1.1rem;
  color: var(--charcoal);
  margin-bottom: 28px;
}

/* ── Code / Pre ── */
pre {
  font-family: var(--mono);
  font-size: 13px;
  background: var(--ivory);
  border: 1px solid var(--border);
  border-left: 3px solid var(--brand);
  padding: 16px 18px;
  border-radius: 4px;
  line-height: 1.6;
  overflow-x: auto;
  margin: 16px 0 24px;
  color: var(--charcoal);
}
code {
  font-family: var(--mono);
  font-size: 0.85em;
  background: var(--ivory);
  padding: 2px 6px;
  border-radius: 3px;
  color: var(--brand);
}

/* ── Tables ── */
table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.9rem;
  margin: 16px 0 28px;
}
th {
  text-align: left;
  font-weight: 600;
  font-size: 0.8rem;
  letter-spacing: 0.5px;
  text-transform: uppercase;
  color: var(--brand);
  border-bottom: 2px solid var(--brand);
  padding: 8px 10px;
}
td {
  padding: 8px 10px;
  border-bottom: 1px solid var(--border);
  vertical-align: top;
}
tr:last-child td { border-bottom: none; }

/* ── Panels ── */
.panel {
  background: var(--ivory);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 18px 20px;
  margin: 20px 0;
}
.panel-label {
  font-family: var(--mono);
  font-size: 10px;
  letter-spacing: 1.5px;
  text-transform: uppercase;
  color: var(--brand);
  margin-bottom: 10px;
}
.warn { background: var(--soft-warn); border-color: #d4a87a; }
.note { background: var(--soft-blue); border-color: #9ab3cc; }

/* ── Tags ── */
.tag {
  display: inline-block;
  background: var(--soft-blue);
  color: var(--brand);
  font-family: var(--mono);
  font-size: 11px;
  font-weight: 600;
  padding: 2px 8px;
  border-radius: 3px;
  margin: 2px 4px 2px 0;
}
.tag-green { background: #d8ede1; color: var(--green); }
.tag-amber { background: #f0e6d2; color: #7a4f1a; }

/* ── Bucket grid (3 themes) ── */
.bucket-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
  gap: 14px;
  margin: 20px 0 28px;
}
.bucket {
  background: var(--ivory);
  border: 1px solid var(--border);
  border-top: 3px solid var(--brand);
  border-radius: 5px;
  padding: 14px 16px;
}
.bucket:nth-child(2) { border-top-color: var(--accent); }
.bucket:nth-child(3) { border-top-color: var(--green); }
.bucket-title {
  font-weight: 600;
  font-size: 0.9rem;
  margin-bottom: 6px;
}

/* ── Chain diagram ── */
.chain {
  font-family: var(--mono);
  font-size: 13px;
  line-height: 2;
  background: var(--ivory);
  border: 1px solid var(--border);
  border-left: 3px solid var(--brand);
  padding: 18px 22px;
  border-radius: 4px;
  margin: 16px 0 28px;
}
.chain .node { color: var(--brand); font-weight: 600; }
.chain .co { color: var(--green); font-style: italic; }
.chain .arrow { color: var(--stone); }

/* ── Quiz ── */
.quiz-section {
  margin: 40px 0;
  border-top: 2px solid var(--border);
  padding-top: 28px;
}
.quiz-intro {
  font-size: 0.95rem;
  color: var(--olive);
  margin-bottom: 24px;
}
.quiz-item { margin-bottom: 28px; }
.quiz-q {
  font-weight: 600;
  margin-bottom: 10px;
}
.quiz-options { list-style: none; padding: 0; }
.quiz-options li {
  margin-bottom: 6px;
}
.quiz-options label {
  display: flex;
  align-items: flex-start;
  gap: 10px;
  cursor: pointer;
  padding: 8px 12px;
  border: 1px solid var(--border);
  border-radius: 4px;
  background: var(--ivory);
  font-size: 0.9rem;
  transition: background 0.15s;
}
.quiz-options label:hover { background: var(--soft-blue); }
.quiz-options input[type=radio] { margin-top: 3px; flex-shrink: 0; }
.quiz-check {
  margin-top: 10px;
  display: none;
  font-size: 0.9rem;
  padding: 10px 14px;
  border-radius: 4px;
}
.quiz-check.correct { background: #d8ede1; color: var(--green); border: 1px solid #a8d4be; }
.quiz-check.wrong { background: var(--soft-warn); color: var(--accent); border: 1px solid #d4a87a; }
.quiz-btn {
  margin-top: 8px;
  background: var(--brand);
  color: white;
  border: none;
  padding: 8px 18px;
  border-radius: 4px;
  cursor: pointer;
  font-family: var(--serif);
  font-size: 0.9rem;
}
.quiz-btn:hover { background: #2a4f8a; }

/* ── Footer / nav ── */
.lesson-footer {
  margin-top: 56px;
  padding-top: 20px;
  border-top: 1px solid var(--border);
  font-size: 0.85rem;
  color: var(--stone);
}
.lesson-footer a { color: var(--brand); text-decoration: none; border-bottom: 1px solid #9ab3cc; }
.lesson-footer a:hover { color: #2a4f8a; }
.ask-reminder {
  margin-top: 28px;
  font-size: 0.85rem;
  background: var(--soft-blue);
  border: 1px solid #9ab3cc;
  border-radius: 5px;
  padding: 12px 16px;
  color: var(--charcoal);
}

/* ── Progress bar ── */
.progress-strip {
  display: flex;
  gap: 6px;
  margin-bottom: 36px;
}
.progress-step {
  flex: 1;
  height: 4px;
  background: var(--border);
  border-radius: 2px;
}
.progress-step.done { background: var(--brand); }
.progress-step.active { background: var(--accent); }

/* ── Breadcrumb ── */
.breadcrumb {
  font-family: var(--mono);
  font-size: 11px;
  letter-spacing: 0.5px;
  color: var(--stone);
  margin-bottom: 28px;
  display: flex;
  align-items: center;
  gap: 6px;
  flex-wrap: wrap;
}
.breadcrumb a {
  color: var(--brand);
  text-decoration: none;
  border-bottom: 1px solid #9ab3cc;
}
.breadcrumb a:hover { color: #2a4f8a; }
.breadcrumb .sep { color: var(--border); }
.breadcrumb .current { color: var(--charcoal); }

/* ── Lesson prev/next navigation ── */
.lesson-nav {
  display: flex;
  gap: 12px;
  margin-top: 28px;
}
.lesson-nav a {
  display: flex;
  flex-direction: column;
  gap: 3px;
  padding: 12px 16px;
  border: 1px solid var(--border);
  border-radius: 6px;
  text-decoration: none;
  color: inherit;
  flex: 1;
  position: relative;
  transition: border-color 0.15s, background 0.15s, opacity 0.15s;
}
.lesson-nav a:not(.nav-locked):hover { border-color: #9ab3cc; background: var(--soft-blue); }
.nav-locked {
  opacity: 0.38;
  cursor: not-allowed;
  pointer-events: auto;
}
.nav-locked::after {
  content: attr(data-tip);
  position: absolute;
  bottom: calc(100% + 8px);
  left: 50%;
  transform: translateX(-50%);
  background: rgba(20, 20, 19, 0.88);
  color: #fff;
  font-family: var(--mono);
  font-size: 0.72rem;
  letter-spacing: 0.2px;
  padding: 5px 11px;
  border-radius: 4px;
  white-space: nowrap;
  pointer-events: none;
  opacity: 0;
  transition: opacity 0.15s;
}
.nav-locked:hover::after { opacity: 1; }
.lesson-nav .nav-label {
  font-family: var(--mono);
  font-size: 10px;
  letter-spacing: 1.5px;
  text-transform: uppercase;
  color: var(--stone);
}
.lesson-nav .nav-title {
  font-size: 0.85rem;
  color: var(--brand);
  line-height: 1.35;
}
.lesson-nav .nav-next { text-align: right; }
.lesson-nav .nav-spacer { flex: 1; }

@media (max-width: 600px) {
  body { padding: 28px 18px 60px; }
  h1 { font-size: 1.5rem; }
  .bucket-grid { grid-template-columns: 1fr; }
  .lesson-nav { flex-direction: column; }
  .lesson-nav .nav-next { text-align: left; }
}