.casebook-foundation,
.casebook-tutorial,
.casebook-paper-intro,
.casebook-reading-order {
  width: min(980px, calc(100% - 32px));
  margin: 30px auto 48px;
  color: var(--ink);
}

.casebook-foundation,
.casebook-paper-intro,
.casebook-reading-order {
  padding: clamp(24px, 4vw, 44px);
  border: 1px solid var(--line);
  border-radius: 16px;
  background: var(--surface);
  box-shadow: var(--shadow);
}

.casebook-foundation {
  border-top: 6px solid var(--state-dark);
}

.casebook-paper-intro {
  border-top: 6px solid var(--block-dark);
}

.casebook-reading-order {
  border-top: 6px solid var(--warm);
}

.casebook-tutorial {
  display: grid;
  gap: 30px;
}

.casebook-opening,
.casebook-subsection,
.casebook-improvement,
.casebook-bridge {
  padding: clamp(22px, 3.5vw, 38px);
  border: 1px solid var(--line);
  border-radius: 14px;
  background: var(--surface);
}

.casebook-opening {
  border-left: 5px solid var(--state-dark);
}

.casebook-subsection {
  border-left: 5px solid var(--block);
}

.casebook-improvement {
  border-left: 5px solid var(--warm);
  background: linear-gradient(180deg, var(--warm-soft), var(--surface));
}

.casebook-bridge {
  border-left: 5px solid var(--quiet);
  background: var(--surface-subtle);
}

.casebook-foundation h2,
.casebook-opening h2,
.casebook-paper-intro > h2,
.casebook-improvement > h2,
.casebook-subsection > h2,
.casebook-reading-order h2 {
  max-width: 26ch;
  margin: 6px 0 18px;
  font-size: clamp(28px, 4vw, 44px);
  line-height: 1.1;
  letter-spacing: -0.025em;
}

.casebook-subsection > h2,
.casebook-improvement > h2 {
  font-size: clamp(25px, 3.2vw, 35px);
}

.casebook-lead {
  max-width: 72ch;
  color: var(--muted);
  font-size: clamp(17px, 2vw, 20px);
  line-height: 1.65;
}

.access-model-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 14px;
  margin: 30px 0;
}

.access-model-card {
  padding: 20px;
  border: 1px solid var(--line);
  border-radius: 12px;
  background: var(--surface-subtle);
}

.access-model-card h3 {
  margin: 0 0 10px;
  font-size: 20px;
}

.access-model-card p {
  font-size: 14px;
  line-height: 1.55;
}

.casebook-example {
  color: var(--quiet);
}

.access-model-formula,
.casebook-query-formula,
.casebook-formula {
  overflow-x: auto;
  margin: 18px 0;
  padding: 16px 18px;
  border-left: 4px solid var(--block);
  background: var(--block-soft);
  text-align: center;
}

.access-model-contrast {
  margin: 22px 0 34px;
  padding: 18px 20px;
  border: 1px solid var(--warm);
  border-radius: 10px;
  background: var(--warm-soft);
}

.circuit-reading-lesson {
  margin-top: 38px;
  padding-top: 28px;
  border-top: 1px solid var(--line);
}

.circuit-demo {
  margin: 22px 0;
  padding: 18px;
  border: 1px solid var(--line);
  border-radius: 12px;
  background: var(--surface-subtle);
  font-family: var(--ui-font);
}

.circuit-demo-row {
  display: grid;
  grid-template-columns: minmax(70px, auto) 1fr 46px 1fr 46px 1fr minmax(90px, auto);
  align-items: center;
  min-height: 58px;
}

.circuit-demo-row i {
  height: 2px;
  background: var(--line-strong);
}

.circuit-demo-row b {
  width: 40px;
  height: 40px;
  display: grid;
  place-items: center;
  border: 2px solid var(--block-dark);
  border-radius: 6px;
  background: var(--surface);
}

.circuit-demo-row .control-dot {
  border: 0;
  border-radius: 50%;
  background: transparent;
  font-size: 22px;
}

.circuit-demo-row .empty-gate {
  border-color: transparent;
  background: transparent;
}

.circuit-legend {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 8px 18px;
  margin: 18px 0;
  padding: 0;
  list-style: none;
}

.circuit-legend li {
  display: grid;
  grid-template-columns: 76px 1fr;
  gap: 8px;
  padding: 10px 0;
  border-bottom: 1px solid var(--line);
}

.circuit-legend code {
  font-weight: 800;
}

.casebook-source-strip {
  display: flex;
  flex-wrap: wrap;
  align-items: stretch;
  gap: 9px;
  margin-top: 28px;
}

.casebook-source-strip > span {
  flex-basis: 100%;
  color: var(--quiet);
  font-family: var(--ui-font);
  font-size: 12px;
  font-weight: 800;
  text-transform: uppercase;
  letter-spacing: 0.06em;
}

.casebook-source-link {
  display: grid;
  gap: 3px;
  min-width: 190px;
  padding: 10px 13px;
  border: 1px solid var(--line);
  border-radius: 9px;
  background: var(--paper);
  text-decoration: none;
}

.casebook-source-link span {
  color: var(--quiet);
  font-size: 11px;
}

.casebook-source-box {
  margin: 26px 0 8px;
  padding: 20px;
  border: 1px solid var(--line-strong);
  border-radius: 12px;
  background: var(--paper);
}

.casebook-source-box h3 {
  margin: 3px 0 7px;
}

.casebook-source-box blockquote {
  margin: 15px 0;
  padding-left: 14px;
  border-left: 4px solid var(--warm);
  font-size: 18px;
  font-style: italic;
}

.casebook-pipeline {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 12px;
  margin: 24px 0 34px;
  counter-reset: pipeline;
}

.casebook-pipeline article {
  counter-increment: pipeline;
  position: relative;
  min-height: 145px;
  padding: 42px 17px 17px;
  border: 1px solid var(--line);
  border-radius: 10px;
  background: var(--surface-subtle);
}

.casebook-pipeline article::before {
  content: counter(pipeline);
  position: absolute;
  top: 13px;
  left: 15px;
  width: 23px;
  height: 23px;
  display: grid;
  place-items: center;
  border-radius: 50%;
  color: #fff;
  background: var(--block-dark);
  font-size: 11px;
  font-weight: 800;
}

.casebook-pipeline p {
  color: var(--muted);
  font-size: 13px;
  line-height: 1.5;
}

.casebook-circuit-guide {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 11px;
  margin: 22px 0;
}

.casebook-circuit-guide article {
  display: grid;
  grid-template-columns: 34px 1fr;
  gap: 12px;
  padding: 16px;
  border: 1px solid var(--line);
  border-radius: 10px;
  background: var(--surface-subtle);
}

.casebook-circuit-guide article > span {
  width: 30px;
  height: 30px;
  display: grid;
  place-items: center;
  border-radius: 50%;
  color: #fff;
  background: var(--state-dark);
  font-weight: 800;
}

.casebook-circuit-guide p {
  margin: 5px 0 0;
  color: var(--muted);
  font-size: 14px;
}

.casebook-pointer {
  color: var(--quiet);
  font-size: 13px;
}

.casebook-theorem-stack,
#case-theorems {
  display: grid;
  gap: 18px;
}

.casebook-theorem {
  padding: 22px;
  border: 1px solid var(--line-strong);
  border-radius: 12px;
  background: var(--paper);
}

.casebook-theorem h3 {
  margin: 4px 0 12px;
  font-size: clamp(22px, 2.8vw, 30px);
}

.casebook-theorem-reading {
  max-width: 75ch;
  font-size: 16px;
  line-height: 1.65;
}

.casebook-proof-steps {
  counter-reset: theorem-step;
  display: grid;
  gap: 8px;
  margin: 15px 0 22px;
  padding: 0;
  list-style: none;
}

.casebook-proof-steps li {
  counter-increment: theorem-step;
  display: grid;
  grid-template-columns: minmax(145px, 0.4fr) 1fr;
  gap: 16px;
  padding: 13px 15px 13px 50px;
  position: relative;
  border-left: 2px solid var(--line-strong);
  background: var(--surface-subtle);
}

.casebook-proof-steps li::before {
  content: counter(theorem-step);
  position: absolute;
  left: 14px;
  top: 12px;
  width: 24px;
  height: 24px;
  display: grid;
  place-items: center;
  border-radius: 50%;
  color: #fff;
  background: var(--block-dark);
  font-size: 11px;
  font-weight: 800;
}

.casebook-proof-steps span {
  color: var(--muted);
  line-height: 1.55;
}

.casebook-lean {
  margin-top: 18px;
  border-top: 1px dashed var(--line-strong);
  padding-top: 14px;
}

.casebook-lean summary,
.advanced-source-audit > summary {
  cursor: pointer;
  color: var(--block-dark);
  font-family: var(--ui-font);
  font-weight: 800;
}

.casebook-lean ul {
  padding-left: 20px;
}

.casebook-lean code {
  overflow-wrap: anywhere;
}

.advanced-source-audit {
  width: min(980px, calc(100% - 32px));
  margin: 28px auto 44px;
  padding: 18px 20px;
  border: 1px solid var(--line);
  border-radius: 12px;
  background: var(--surface-subtle);
}

.advanced-source-audit[open] > summary {
  margin-bottom: 14px;
}

.advanced-audit-intro {
  color: var(--muted);
  font-size: 14px;
}

.advanced-source-audit > .content-section {
  width: 100%;
  margin: 0;
  padding: 12px 0 0;
  border: 0;
  box-shadow: none;
  background: transparent;
}

.casebook-reading-order ol {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 10px;
  padding-left: 20px;
}

.casebook-reading-order li {
  padding: 10px;
  line-height: 1.5;
}

@media (max-width: 850px) {
  .access-model-grid,
  .casebook-pipeline,
  .casebook-reading-order ol {
    grid-template-columns: 1fr;
  }

  .casebook-circuit-guide,
  .circuit-legend {
    grid-template-columns: 1fr;
  }

  .casebook-proof-steps li {
    grid-template-columns: 1fr;
  }

  .circuit-demo {
    overflow-x: auto;
  }

  .circuit-demo-row {
    min-width: 620px;
  }
}

@media print {
  .casebook-lean,
  .advanced-source-audit {
    break-inside: avoid;
  }
}