/* CS267 textbook learning layer: editorial structure, not a second dashboard. */
body.cs267-textbook .page {
  width: min(1120px, calc(100% - 36px));
}

.lesson-hero {
  max-width: 900px;
}

.lesson-pager {
  display: flex;
  gap: 18px;
  justify-content: flex-end;
  min-height: 1.5rem;
  margin: -1.6rem 0 1.2rem;
  font-size: 0.8rem;
}

.lesson-pager a {
  color: var(--muted);
  text-decoration: none;
}

.learning-map {
  margin-top: 30px;
  padding: 22px 0 22px 20px;
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
  border-left: 3px solid var(--accent);
}

.learning-map h2 {
  margin: 4px 0 10px;
  font-size: clamp(1.45rem, 3vw, 2rem);
}

.learning-map-kicker,
.lesson-build-kicker,
.concept-lab-eyebrow {
  margin: 0;
  color: var(--accent-dark);
  font-size: 0.7rem;
  font-weight: 850;
  letter-spacing: 0.09em;
  text-transform: uppercase;
}

.learning-problem {
  max-width: 760px;
  margin: 0;
  color: var(--muted);
}

.learning-flow {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  align-items: center;
  margin-top: 16px;
}

.learning-flow-node {
  padding: 5px 9px;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: rgba(255, 253, 248, 0.72);
  font-size: 0.8rem;
  font-weight: 750;
}

.learning-flow-arrow {
  color: var(--muted);
}

.lesson-shell {
  display: grid;
  grid-template-columns: minmax(0, 820px) minmax(200px, 230px);
  gap: 48px;
  align-items: start;
  margin-top: 24px;
}

.lesson-main {
  min-width: 0;
}

.lesson-main h2,
.lesson-main h3,
.before-start,
.deep-quiz,
.open-practice,
.explain-checklist,
.reasoning-start {
  scroll-margin-top: 92px;
}

.lesson-toc {
  position: sticky;
  top: 88px;
  max-height: calc(100vh - 112px);
  overflow-y: auto;
  padding: 18px 0 18px 18px;
  border-left: 1px solid var(--line);
}

.lesson-toc-label {
  display: flex;
  justify-content: space-between;
  margin: 0 0 12px;
  color: var(--muted);
  font-size: 0.7rem;
  font-weight: 850;
  letter-spacing: 0.11em;
  text-transform: uppercase;
}

.lesson-toc-progress {
  color: var(--accent);
  font-variant-numeric: tabular-nums;
}

.lesson-toc nav {
  display: grid;
  gap: 3px;
}

.lesson-toc a,
.lesson-toc-mobile a {
  padding: 6px 9px;
  border-left: 2px solid transparent;
  color: var(--muted);
  font-size: 0.82rem;
  line-height: 1.35;
  text-decoration: none;
}

.lesson-toc a:hover,
.lesson-toc a:focus-visible,
.lesson-toc a.is-active,
.lesson-toc-mobile a.is-active {
  border-left-color: var(--accent);
  color: var(--ink);
  background: color-mix(in srgb, var(--accent-soft) 38%, transparent);
}

.lesson-toc-mobile {
  display: none;
}

.before-start,
.deep-quiz,
.open-practice,
.explain-checklist,
.reasoning-start {
  margin: 42px 0;
}

.before-start,
.open-practice,
.explain-checklist,
.reasoning-start {
  padding: 24px 0;
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
}

.before-start h2,
.deep-quiz h2,
.open-practice h2,
.explain-checklist h2,
.reasoning-start h2 {
  margin-top: 0;
}

.reasoning-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 0 28px;
}

.reasoning-grid article {
  padding: 16px 0;
  border-bottom: 1px solid var(--line);
}

.reasoning-label {
  margin: 0;
  color: var(--accent-dark);
  font-size: 0.7rem;
  font-weight: 850;
  letter-spacing: 0.09em;
  text-transform: uppercase;
}

.reasoning-grid article p:last-child {
  margin: 0.45rem 0 0;
}

.before-start-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 14px 24px;
  margin-top: 18px;
}

.before-prompt,
.open-prompt,
.deep-quiz-item {
  padding: 13px 0;
  border-bottom: 1px solid var(--line);
}

.before-prompt summary,
.open-prompt summary,
.deep-quiz-item summary,
.legacy-quiz-bank > summary {
  cursor: pointer;
  font-weight: 750;
}

.before-prompt p,
.open-guide p {
  margin-bottom: 0;
  color: var(--muted);
}

.claim-legend {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  align-items: center;
  margin: 20px 0 0;
}

.claim-legend span {
  padding: 4px 8px;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: var(--paper-raised);
  font-size: 0.76rem;
}

.teaching-block {
  position: relative;
  margin: 28px 0;
  padding: 24px 22px 20px;
  border: 0;
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
  border-left: 3px solid var(--accent);
  border-radius: 0;
  background: color-mix(in srgb, var(--accent-soft) 22%, transparent);
  box-shadow: none;
}

.teaching-block::before {
  display: block;
  margin-bottom: 10px;
  color: var(--accent-dark);
  content: attr(data-block-label);
  font-size: 0.7rem;
  font-weight: 850;
  letter-spacing: 0.09em;
  text-transform: uppercase;
}

.teaching-block.misconception-block {
  border-left-color: var(--warn);
  background: color-mix(in srgb, var(--warn-soft) 32%, transparent);
}

.concept-lab {
  margin: 42px 0;
}

.concept-lab-eyebrow,
.follow-up-label {
  margin-bottom: 12px;
}

.practice-question {
  margin: 0;
}

.practice-prompt {
  margin: 0 0 14px;
  font-weight: 700;
}

.practice-options {
  display: grid;
  gap: 8px;
  margin: 0;
  padding: 0;
  border: 0;
}

.practice-option {
  display: flex;
  gap: 10px;
  align-items: flex-start;
  padding: 11px 13px;
  border: 1px solid var(--line);
  border-radius: 9px;
  background: var(--paper);
  cursor: pointer;
}

.practice-option:hover,
.practice-option:focus-within {
  border-color: var(--accent);
  background: var(--accent-soft);
}

.practice-option input {
  margin-top: 0.28em;
  accent-color: var(--accent-dark);
}

.practice-option.is-correct {
  border-color: #3fcf72;
  background: rgba(99,230,140,.1);
}

.practice-option.is-selected-wrong {
  border-color: #ff8a75;
  background: rgba(255,107,94,.1);
}

.practice-actions {
  display: flex;
  gap: 10px;
  margin-top: 14px;
}

.practice-submit,
.practice-retry {
  padding: 9px 15px;
  border: 1px solid var(--accent-dark);
  border-radius: 8px;
  color: white;
  background: var(--accent-dark);
  cursor: pointer;
  font: inherit;
  font-weight: 750;
}

.practice-retry {
  color: var(--accent-dark);
  background: transparent;
}

.practice-explanation:not(:empty) {
  margin-top: 16px;
  padding-top: 14px;
  border-top: 1px dashed var(--line);
}

.practice-result {
  font-weight: 850;
}

.practice-explanation.is-correct .practice-result {
  color: #9ef0bb;
}

.practice-explanation.is-incorrect .practice-result,
.practice-explanation.is-empty {
  color: #ffb3a8;
}

.option-reasons {
  margin-bottom: 0;
  padding-left: 1.4rem;
  color: var(--muted);
}

.option-reasons li {
  margin: 8px 0;
}

.option-reasons .is-answer {
  color: var(--ink);
}

.follow-up {
  margin-top: 20px;
  padding: 18px 0 0 18px;
  border-top: 1px solid var(--line);
  border-left: 2px solid var(--line);
}

.deep-quiz {
  padding-top: 10px;
  border-top: 2px solid var(--ink);
}

.deep-quiz-progress {
  color: var(--muted);
  font-variant-numeric: tabular-nums;
}

.deep-quiz-level {
  display: inline-block;
  min-width: 7rem;
  margin-right: 0.5rem;
  color: var(--accent-dark);
  font-size: 0.7rem;
  font-weight: 850;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}

.deep-quiz-item > .practice-question {
  padding-top: 18px;
}

.legacy-quiz-bank {
  margin: 30px 0;
  padding: 15px 0;
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
}

.legacy-quiz-bank > .quiz {
  box-shadow: none;
}

.closed-book ul {
  display: grid;
  gap: 10px;
  padding: 0;
  list-style: none;
}

.closed-book li {
  display: grid;
  grid-template-columns: 1.2rem 1fr;
  gap: 8px;
  margin: 0;
  padding: 10px 0;
  border-bottom: 1px solid color-mix(in srgb, var(--line) 72%, transparent);
}

.closed-book li > span:first-child {
  color: var(--accent);
  font-weight: 800;
}

.lesson-build-bridge {
  margin: 34px 0;
  padding: 22px 0 22px 20px;
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
  border-left: 3px solid var(--accent);
}

.lesson-build-bridge h3 {
  margin: 6px 0 8px;
}

.lesson-build-bridge p {
  margin: 0 0 10px;
}

.lesson-build-bridge a {
  font-weight: 750;
}

@media (max-width: 1040px) {
  body.cs267-textbook .page {
    width: min(820px, calc(100% - 36px));
  }

  .lesson-shell {
    grid-template-columns: minmax(0, 1fr);
    gap: 0;
  }

  .lesson-toc {
    display: none;
  }

  .lesson-toc-mobile {
    display: block;
    margin-top: 18px;
    padding: 12px 0;
    border-top: 1px solid var(--line);
    border-bottom: 1px solid var(--line);
  }

  .lesson-toc-mobile summary {
    cursor: pointer;
    font-weight: 800;
  }

  .lesson-toc-mobile nav {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 6px 18px;
    margin-top: 12px;
  }
}

@media (max-width: 720px) {
  body.cs267-textbook .page {
    width: min(100% - 28px, 820px);
    padding-top: 24px;
  }

  .lesson-pager {
    position: static;
    justify-content: space-between;
    margin: 0 0 18px;
  }

  .lesson-toc-mobile nav,
  .before-start-grid,
  .reasoning-grid {
    grid-template-columns: 1fr;
  }

  .teaching-block {
    padding-right: 14px;
    padding-left: 16px;
  }

  .learning-flow-arrow {
    display: none;
  }
}

@media print {
  .lesson-toc,
  .lesson-toc-mobile,
  .practice-actions {
    display: none;
  }

  .lesson-shell {
    display: block;
  }
}
/* The shared lesson runtime also builds a generic .pb-toc. CS267 has a
   course-aware TOC with practice progress, so keep a single navigation. */
body.cs267-textbook > .pb-toc {
  display: none !important;
}