:root {
  color-scheme: light;
  --chapter-canvas: #e9e2d8;
  --chapter-paper: #fbf9f5;
  --chapter-paper-strong: #fffdf9;
  --chapter-paper-muted: #f4efe8;
  --chapter-ink: #25211e;
  --chapter-ink-soft: #514a44;
  --chapter-muted: #746b63;
  --chapter-faint: #a1978d;
  --chapter-line: #ddd4c9;
  --chapter-line-soft: #ece5dc;
  --chapter-accent: #a34f36;
  --chapter-accent-dark: #7d3827;
  --chapter-accent-soft: #f3e5df;
  --chapter-navy: #17385f;
  --chapter-navy-soft: #eaf0f6;
  --chapter-success: #35705a;
  --chapter-success-soft: #e7f1ec;
  --chapter-shadow: rgba(80, 56, 42, 0.15);
  font-family: "Source Sans 3", sans-serif;
}

* {
  box-sizing: border-box;
}

html {
  min-width: 0;
  scroll-behavior: smooth;
}

body {
  min-width: 0;
  margin: 0;
  background: var(--chapter-paper);
  color: var(--chapter-ink);
}

button,
a {
  font: inherit;
}

.chapter-overview-shell button:focus-visible,
.chapter-overview-shell a:focus-visible,
.chapter-prototype-shell button:focus-visible,
.chapter-prototype-shell a:focus-visible,
.chapter-lesson-clickover button:focus-visible,
.chapter-lesson-clickover a:focus-visible {
  outline: 0.18rem solid #c36547;
  outline-offset: 0.18rem;
}

.chapter-overview-shell,
.chapter-prototype-shell {
  min-height: 100dvh;
  overflow-x: clip;
  background:
    radial-gradient(circle at 8% 0%, rgba(255, 253, 249, 0.92), transparent 34rem),
    radial-gradient(circle at 94% 90%, rgba(163, 79, 54, 0.065), transparent 31rem),
    var(--chapter-paper);
}

.chapter-prototype-shell {
  padding-bottom: 7.25rem;
}

.chapter-skip-link {
  position: fixed;
  top: 0.75rem;
  left: 0.75rem;
  z-index: 100;
  padding: 0.6rem 0.8rem;
  border-radius: 0.25rem;
  background: var(--chapter-navy);
  color: #fff;
  text-decoration: none;
  transform: translateY(-180%);
}

.chapter-skip-link:focus {
  transform: translateY(0);
}

.chapter-prototype-flag {
  min-height: 1.9rem;
  display: grid;
  place-items: center;
  padding: 0.25rem 1rem;
  background: var(--chapter-navy);
  color: #fff;
  font-size: 0.7rem;
  font-weight: 750;
  letter-spacing: 0.095em;
  text-align: center;
  text-transform: uppercase;
}

.chapter-edition-navigation {
  min-height: 2.65rem;
  padding: 0.35rem 1rem;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 1.1rem;
  border-bottom: 1px solid var(--chapter-line);
  background: var(--chapter-paper-strong);
  color: var(--chapter-ink-soft);
  font-size: 0.84rem;
}

.chapter-edition-navigation strong {
  color: var(--chapter-accent-dark);
  font-weight: 800;
}

.chapter-edition-navigation a {
  color: var(--chapter-accent);
  font-weight: 750;
  text-underline-offset: 0.18em;
}

.chapter-edition-divider {
  width: 1px;
  height: 1rem;
  background: var(--chapter-line);
}

.chapter-site-header {
  min-height: 6.25rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1.5rem;
  padding: 1.2rem clamp(1rem, 4vw, 4.5rem);
  border-bottom: 1px solid var(--chapter-line-soft);
  background: rgba(255, 253, 249, 0.84);
}

.chapter-site-brand {
  display: grid;
  color: var(--chapter-navy);
  font-family: Georgia, "Times New Roman", serif;
  font-size: clamp(1.35rem, 2.3vw, 2rem);
  font-weight: 700;
  line-height: 0.98;
  letter-spacing: -0.035em;
  text-decoration: none;
}

.chapter-site-tools {
  display: flex;
  align-items: center;
  gap: 1rem;
  color: var(--chapter-muted);
  font-size: 0.84rem;
  font-weight: 700;
}

.chapter-site-tools span {
  padding: 0.22rem 0.55rem;
  border: 1px solid var(--chapter-line);
  border-radius: 999px;
  background: var(--chapter-paper-muted);
}

.chapter-site-tools a {
  color: var(--chapter-navy);
  text-underline-offset: 0.18em;
}

.chapter-strip {
  min-height: 3.7rem;
  display: grid;
  grid-template-columns: repeat(5, minmax(8.5rem, 1fr));
  padding-inline: clamp(0.5rem, 3vw, 3rem);
  overflow-x: auto;
  border-bottom: 1px solid var(--chapter-line);
  background: var(--chapter-paper-strong);
}

.chapter-strip-item,
.chapter-strip-current {
  min-width: 8.5rem;
  min-height: 3.7rem;
  display: grid;
  place-items: center;
  border: 0;
  border-left: 1px solid var(--chapter-line-soft);
  background: transparent;
  color: var(--chapter-muted);
  font-size: 0.76rem;
  font-weight: 700;
  text-decoration: none;
}

.chapter-strip > :last-child {
  border-right: 1px solid var(--chapter-line-soft);
}

.chapter-strip-current {
  grid-template-columns: auto auto;
  align-content: center;
  justify-content: center;
  column-gap: 0.4rem;
  padding: 0.4rem 0.85rem;
  border-bottom: 0.22rem solid var(--chapter-accent);
  background: var(--chapter-accent-soft);
  color: var(--chapter-accent-dark);
  cursor: pointer;
}

.chapter-strip-current strong {
  color: var(--chapter-ink);
  font-size: 0.86rem;
}

.chapter-strip-current span:last-child {
  grid-column: 1 / -1;
  color: var(--chapter-accent);
  font-size: 0.66rem;
  letter-spacing: 0.04em;
  text-transform: uppercase;
}

.chapter-overview-main {
  width: 100%;
  margin-inline: auto;
}

.chapter-overline,
.chapter-section-heading > p,
.chapter-index-heading-row > div > p,
.chapter-map-board-heading > p {
  margin: 0 0 0.65rem;
  color: var(--chapter-accent);
  font-size: 0.72rem;
  font-weight: 850;
  letter-spacing: 0.115em;
  text-transform: uppercase;
}

.chapter-overview-main h1,
.chapter-overview-main h2,
.chapter-overview-main h3,
.chapter-overview-main h4,
.chapter-clickover h2 {
  margin: 0;
  color: var(--chapter-ink);
  font-family: Georgia, "Times New Roman", serif;
  font-weight: 600;
  letter-spacing: -0.035em;
  text-wrap: balance;
}

.chapter-overview-main h1 {
  max-width: 11ch;
  font-size: clamp(3.4rem, 8vw, 7.8rem);
  line-height: 0.83;
}

.chapter-overview-main h2 {
  max-width: 19ch;
  font-size: clamp(1.8rem, 3.6vw, 3.2rem);
  line-height: 1;
}

.chapter-overview-main h3 {
  font-size: clamp(1.2rem, 1.7vw, 1.55rem);
  line-height: 1.12;
}

.chapter-overview-main p {
  text-wrap: pretty;
}

.chapter-promise {
  margin: 1.5rem 0 0;
  color: var(--chapter-ink-soft);
  font-size: clamp(1.08rem, 1.7vw, 1.35rem);
  font-weight: 550;
  line-height: 1.45;
}

.chapter-route-status {
  display: inline-flex;
  align-items: center;
  min-height: 1.45rem;
  padding: 0.1rem 0.5rem;
  border: 1px solid var(--chapter-line);
  border-radius: 999px;
  color: var(--chapter-muted);
  background: var(--chapter-paper-muted);
  font-size: 0.66rem;
  font-weight: 800;
  letter-spacing: 0.035em;
  line-height: 1;
  white-space: nowrap;
  text-transform: uppercase;
}

.chapter-route-status--available {
  border-color: #a7c9b8;
  background: var(--chapter-success-soft);
  color: var(--chapter-success);
}

.chapter-route-status--checking {
  opacity: 0.7;
}

.chapter-open-action,
.chapter-primary-cta {
  min-height: 2.55rem;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0.58rem 0.9rem;
  border: 1px solid var(--chapter-accent);
  border-radius: 0.25rem;
  background: var(--chapter-accent);
  color: #fff;
  font-size: 0.79rem;
  font-weight: 800;
  line-height: 1;
  text-decoration: none;
  white-space: nowrap;
  cursor: pointer;
}

.chapter-open-action:hover,
.chapter-primary-cta:hover {
  border-color: var(--chapter-accent-dark);
  background: var(--chapter-accent-dark);
}

.chapter-open-action:disabled {
  border-color: var(--chapter-line);
  background: var(--chapter-paper-muted);
  color: var(--chapter-faint);
  cursor: not-allowed;
}

.chapter-open-action--compact {
  min-height: 2rem;
  padding: 0.42rem 0.68rem;
  font-size: 0.72rem;
}

.chapter-lesson-number {
  color: var(--chapter-accent);
  font-family: Georgia, "Times New Roman", serif;
  font-size: 1.55rem;
  font-variant-numeric: tabular-nums;
  line-height: 1;
}

.chapter-concept-list {
  display: flex;
  flex-wrap: wrap;
  gap: 0.35rem;
  margin: 0;
  padding: 0;
  list-style: none;
}

.chapter-concept-list li {
  padding: 0.18rem 0.46rem;
  border: 1px solid var(--chapter-line-soft);
  border-radius: 999px;
  background: var(--chapter-paper-strong);
  color: var(--chapter-muted);
  font-size: 0.68rem;
  font-weight: 700;
}

/* Variant A: a reading-first introduction alongside a numbered vertical path. */
.chapter-overview-main--path {
  display: grid;
  grid-template-columns: minmax(18rem, 0.78fr) minmax(30rem, 1.22fr);
  gap: clamp(2.5rem, 6vw, 7rem);
  padding: clamp(3.5rem, 7vw, 7rem) clamp(1.25rem, 5vw, 6rem);
}

.chapter-path-introduction {
  position: sticky;
  top: 1.5rem;
  align-self: start;
}

.chapter-path-introduction h1 {
  color: var(--chapter-navy);
}

.chapter-introduction-copy {
  margin-top: 2.25rem;
  padding-top: 1.5rem;
  border-top: 1px solid var(--chapter-line);
}

.chapter-introduction-copy p {
  margin: 0 0 1rem;
  max-width: 47ch;
  color: var(--chapter-ink-soft);
  font-family: Georgia, "Times New Roman", serif;
  font-size: 1.04rem;
  line-height: 1.68;
}

.chapter-begin-card {
  margin-top: 2.2rem;
  padding: 1.25rem;
  border-left: 0.23rem solid var(--chapter-accent);
  background: var(--chapter-accent-soft);
}

.chapter-begin-label {
  color: var(--chapter-accent-dark);
  font-size: 0.68rem;
  font-weight: 850;
  letter-spacing: 0.09em;
  text-transform: uppercase;
}

.chapter-begin-card p {
  margin: 0.55rem 0 1rem;
  color: var(--chapter-ink-soft);
  line-height: 1.5;
}

.chapter-section-heading {
  padding-bottom: 2rem;
  border-bottom: 1px solid var(--chapter-line);
}

.chapter-path-list {
  margin: 0;
  padding: 0;
  list-style: none;
}

.chapter-path-item {
  display: grid;
  grid-template-columns: 3.25rem minmax(0, 1fr);
  gap: 1rem;
  padding: 1.8rem 0;
  border-bottom: 1px solid var(--chapter-line-soft);
}

.chapter-path-copy {
  min-width: 0;
}

.chapter-lesson-heading-row {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 1rem;
}

.chapter-arc-label {
  margin: 0 0 0.28rem;
  color: var(--chapter-accent);
  font-size: 0.7rem;
  font-weight: 800;
  text-transform: uppercase;
}

.chapter-path-copy > p {
  max-width: 66ch;
  margin: 0.75rem 0 1rem;
  color: var(--chapter-ink-soft);
  line-height: 1.55;
}

.chapter-lesson-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}

/* Variant B: a dense, scan-first directory with a fixed orientation column. */
.chapter-overview-main--index {
  display: grid;
  grid-template-columns: minmax(19rem, 34vw) minmax(38rem, 1fr);
  min-height: calc(100dvh - 12.6rem);
  border-bottom: 1px solid var(--chapter-line-soft);
}

.chapter-index-orientation {
  border-right: 1px solid var(--chapter-line);
  background: var(--chapter-navy);
  color: #fff;
}

.chapter-index-orientation-inner {
  position: sticky;
  top: 0;
  padding: clamp(3rem, 6vw, 6rem) clamp(1.5rem, 4vw, 4rem);
}

.chapter-index-orientation .chapter-overline,
.chapter-index-orientation h1,
.chapter-index-orientation .chapter-promise {
  color: #fff;
}

.chapter-index-orientation h1 {
  max-width: none;
  font-size: clamp(3.35rem, 5vw, 4.8rem);
}

.chapter-index-orientation .chapter-promise {
  max-width: 31ch;
  font-size: 1.06rem;
  line-height: 1.55;
  opacity: 0.88;
}

.chapter-index-introduction {
  max-width: 34ch;
  margin: 1.25rem 0 0;
  color: #dce6f0;
  font-family: Georgia, "Times New Roman", serif;
  font-size: 0.93rem;
  line-height: 1.58;
}

.chapter-index-note {
  margin: 2.5rem 0;
  padding: 1.1rem 0;
  border-block: 1px solid rgba(255, 255, 255, 0.22);
}

.chapter-index-note span {
  color: #d8e3ef;
  font-size: 0.67rem;
  font-weight: 850;
  letter-spacing: 0.1em;
  text-transform: uppercase;
}

.chapter-index-note p {
  margin: 0.65rem 0 0;
  color: #fff;
  font-family: Georgia, "Times New Roman", serif;
  font-size: 1rem;
  line-height: 1.58;
}

.chapter-index-orientation .chapter-open-action,
.chapter-index-orientation .chapter-primary-cta {
  border-color: #fff;
  background: #fff;
  color: var(--chapter-navy);
}

.chapter-index-orientation .chapter-open-action:hover,
.chapter-index-orientation .chapter-primary-cta:hover {
  border-color: #fff;
  background: var(--chapter-navy-soft);
  color: var(--chapter-navy);
}

.chapter-index-orientation .chapter-open-action:disabled {
  border-color: rgba(255, 255, 255, 0.25);
  background: rgba(255, 255, 255, 0.09);
  color: rgba(255, 255, 255, 0.58);
}

.chapter-index-directory {
  min-width: 0;
  padding: clamp(2.5rem, 5vw, 5rem) clamp(1.25rem, 4vw, 4rem);
}

.chapter-index-heading-row {
  display: flex;
  align-items: end;
  justify-content: space-between;
  gap: 1.5rem;
  padding-bottom: 1.5rem;
}

.chapter-index-heading-row > span {
  flex: 0 0 auto;
  color: var(--chapter-muted);
  font-size: 0.7rem;
  font-weight: 700;
}

.chapter-index-table {
  border-top: 0.12rem solid var(--chapter-ink);
}

.chapter-index-row {
  display: grid;
  grid-template-columns: 2.8rem minmax(8.5rem, 0.7fr) minmax(15rem, 1.5fr) minmax(7.5rem, auto);
  gap: 1rem;
  align-items: center;
  padding: 1.1rem 0;
  border-bottom: 1px solid var(--chapter-line);
  transition: background-color 160ms ease, padding-inline 160ms ease;
  animation: chapter-index-reveal 320ms cubic-bezier(0.22, 1, 0.36, 1) both;
}

.chapter-index-row:nth-child(2) { animation-delay: 45ms; }
.chapter-index-row:nth-child(3) { animation-delay: 90ms; }
.chapter-index-row:nth-child(4) { animation-delay: 135ms; }
.chapter-index-row:nth-child(5) { animation-delay: 180ms; }
.chapter-index-row:nth-child(6) { animation-delay: 225ms; }

.chapter-index-row:has(a:hover),
.chapter-index-row:has(a:focus-visible) {
  margin-inline: -0.7rem;
  padding-inline: 0.7rem;
  background: var(--chapter-paper-muted);
}

.chapter-index-row-title p {
  margin: 0 0 0.2rem;
  color: var(--chapter-accent);
  font-size: 0.65rem;
  font-weight: 800;
  letter-spacing: 0.04em;
  text-transform: uppercase;
}

.chapter-index-row-title h3 {
  font-size: 1.12rem;
}

.chapter-index-target {
  margin: 0;
  color: var(--chapter-ink-soft);
  font-size: 0.87rem;
  line-height: 1.45;
}

.chapter-index-action {
  display: grid;
  justify-items: end;
  gap: 0.45rem;
}

@keyframes chapter-index-reveal {
  from {
    opacity: 0;
    clip-path: inset(0 0 100% 0);
    transform: translateY(0.65rem);
  }
  to {
    opacity: 1;
    clip-path: inset(0 0 0 0);
    transform: translateY(0);
  }
}

/* Variant C: a grouped map that makes the three program jobs primary. */
.chapter-overview-main--map {
  padding: clamp(3rem, 6vw, 6rem) clamp(1.25rem, 5vw, 6rem);
}

.chapter-map-introduction {
  display: grid;
  grid-template-columns: minmax(18rem, 0.9fr) minmax(18rem, 1.1fr);
  gap: clamp(2rem, 7vw, 8rem);
  align-items: end;
  padding-bottom: clamp(2.5rem, 5vw, 5rem);
}

.chapter-map-introduction h1 {
  color: var(--chapter-navy);
}

.chapter-map-introduction .chapter-promise {
  max-width: 46ch;
  margin: 0;
  padding-left: 1.5rem;
  border-left: 0.2rem solid var(--chapter-accent);
  font-family: Georgia, "Times New Roman", serif;
}

.chapter-map-board {
  display: grid;
  grid-template-columns: minmax(14rem, 0.36fr) minmax(36rem, 1.64fr);
  gap: clamp(1.8rem, 4vw, 4rem);
  padding: clamp(1.5rem, 4vw, 3.5rem);
  border: 1px solid var(--chapter-line);
  background: var(--chapter-paper-strong);
  box-shadow: 0 1.4rem 4rem rgba(80, 56, 42, 0.07);
}

.chapter-map-board-heading {
  padding-right: 1.2rem;
  border-right: 1px solid var(--chapter-line);
}

.chapter-map-board-heading h2 {
  font-size: clamp(1.8rem, 3vw, 2.7rem);
}

.chapter-map-board-heading > p:last-child {
  margin: 1.4rem 0 0;
  color: var(--chapter-ink-soft);
  font-family: Georgia, "Times New Roman", serif;
  font-size: 1rem;
  font-weight: 400;
  letter-spacing: 0;
  line-height: 1.63;
  text-transform: none;
}

.chapter-map-groups {
  min-width: 0;
}

.chapter-map-group {
  display: grid;
  grid-template-columns: minmax(10rem, 0.42fr) minmax(18rem, 1.58fr);
  gap: 1.5rem;
  padding: 1.45rem 0;
  border-bottom: 1px solid var(--chapter-line);
}

.chapter-map-group:first-child {
  padding-top: 0;
}

.chapter-map-group:last-child {
  padding-bottom: 0;
  border-bottom: 0;
}

.chapter-map-group-label {
  display: flex;
  gap: 0.75rem;
  align-items: flex-start;
}

.chapter-map-group-label > span {
  color: var(--chapter-accent);
  font-family: Georgia, "Times New Roman", serif;
  font-size: 1.1rem;
}

.chapter-map-group-label h3 {
  font-size: 1.2rem;
}

.chapter-map-group-label p {
  margin: 0.4rem 0 0;
  color: var(--chapter-muted);
  font-size: 0.78rem;
  line-height: 1.4;
}

.chapter-map-lessons {
  display: grid;
  gap: 0.65rem;
}

.chapter-map-lesson {
  padding: 1rem 1.15rem;
  border-left: 0.18rem solid var(--chapter-line);
  background: var(--chapter-paper-muted);
}

.chapter-map-lesson-topline,
.chapter-map-lesson-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}

.chapter-map-lesson-topline > span:first-child {
  color: var(--chapter-accent);
  font-size: 0.66rem;
  font-weight: 850;
  letter-spacing: 0.07em;
  text-transform: uppercase;
}

.chapter-map-lesson h4 {
  margin-top: 0.45rem;
  font-size: 1.12rem;
}

.chapter-map-lesson > p {
  margin: 0.55rem 0 0.8rem;
  color: var(--chapter-ink-soft);
  font-size: 0.84rem;
  line-height: 1.45;
}

.chapter-map-lesson-footer > span {
  color: var(--chapter-muted);
  font-size: 0.7rem;
  font-weight: 650;
}

/* Shared compact chapter clickover. */
.chapter-clickover-backdrop {
  position: fixed;
  inset: 0;
  z-index: 70;
  display: grid;
  align-items: start;
  justify-items: center;
  padding: 10.6rem 1rem 6rem;
  overflow-y: auto;
  background: rgba(23, 56, 95, 0.24);
  backdrop-filter: blur(0.18rem);
}

.chapter-clickover {
  width: min(62rem, 100%);
  max-height: calc(100dvh - 12rem);
  overflow-y: auto;
  border: 1px solid var(--chapter-line);
  background: var(--chapter-paper-strong);
  box-shadow: 0 1.7rem 5rem rgba(31, 26, 23, 0.24);
}

.chapter-clickover:focus,
.chapter-lesson-clickover:focus {
  outline: none;
}

.chapter-clickover-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  padding: 1.1rem 1.3rem;
  border-bottom: 1px solid var(--chapter-line);
}

.chapter-clickover-header p {
  margin: 0 0 0.2rem;
  color: var(--chapter-accent);
  font-size: 0.66rem;
  font-weight: 850;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.chapter-clickover-header h2 {
  font-size: 1.55rem;
}

.chapter-clickover-header button,
.chapter-clickover-footer button {
  border: 0;
  background: transparent;
  color: var(--chapter-accent);
  font-size: 0.77rem;
  font-weight: 800;
  text-decoration: underline;
  text-underline-offset: 0.18em;
  cursor: pointer;
}

.chapter-clickover-promise {
  margin: 0;
  padding: 1rem 1.3rem;
  border-bottom: 1px solid var(--chapter-line-soft);
  color: var(--chapter-ink-soft);
  font-family: Georgia, "Times New Roman", serif;
  line-height: 1.45;
}

.chapter-clickover-list {
  margin: 0;
  padding: 0;
  list-style: none;
}

.chapter-clickover-list li {
  border-bottom: 1px solid var(--chapter-line-soft);
}

.chapter-clickover-row {
  display: grid;
  grid-template-columns: 1.6rem minmax(9rem, 1fr) auto auto;
  gap: 0.85rem;
  align-items: center;
  padding: 0.8rem 1.3rem;
  color: inherit;
  text-decoration: none;
}

.chapter-clickover-row--available {
  cursor: pointer;
  transition: background-color 140ms ease;
}

.chapter-clickover-row--available:hover {
  background: var(--chapter-paper-muted);
}

.chapter-clickover-current .chapter-clickover-row--available:hover {
  background: transparent;
}

.chapter-clickover-row--available:focus-visible {
  outline: 0.18rem solid #c36547;
  outline-offset: -0.25rem;
}

.chapter-clickover-number {
  color: var(--chapter-accent);
  font-family: Georgia, "Times New Roman", serif;
  font-size: 1.15rem;
}

.chapter-clickover-copy {
  display: grid;
  gap: 0.16rem;
}

.chapter-clickover-list strong {
  color: var(--chapter-ink);
  font-family: Georgia, "Times New Roman", serif;
  font-size: 0.98rem;
}

.chapter-clickover-copy > span {
  color: var(--chapter-muted);
  font-size: 0.7rem;
}

.chapter-clickover-list .chapter-clickover-state {
  display: grid;
  justify-items: end;
  gap: 0.25rem;
}

.chapter-current-marker {
  color: var(--chapter-accent-dark) !important;
  font-size: 0.62rem !important;
  font-weight: 850;
  letter-spacing: 0.055em;
  text-transform: uppercase;
  white-space: nowrap;
}

.chapter-clickover-current {
  box-shadow: inset 0.2rem 0 0 var(--chapter-accent);
  background: var(--chapter-accent-soft);
}

.chapter-clickover-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  padding: 0.95rem 1.3rem;
  background: var(--chapter-paper-muted);
  color: var(--chapter-muted);
  font-size: 0.75rem;
}

/* Student-facing chapter directory inside the canonical lesson shell. */
.chapter-lesson-clickover {
  width: 100%;
  max-height: min(38rem, calc(100dvh - 8.25rem));
  display: grid;
  grid-template-columns: minmax(15rem, 0.42fr) minmax(32rem, 1.58fr);
  overflow: hidden;
  border: 1px solid var(--chapter-line);
  background: var(--chapter-paper-strong);
  color: var(--chapter-ink);
  box-shadow: 0 1.5rem 4rem rgba(23, 56, 95, 0.22);
}

.chapter-lesson-clickover-orientation {
  padding: 1.45rem;
  background: var(--chapter-navy);
  color: #fff;
}

.chapter-lesson-clickover-orientation > p,
.chapter-lesson-clickover-directory header p {
  margin: 0 0 0.32rem;
  color: #dce6f0;
  font-size: 0.65rem;
  font-weight: 850;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.chapter-lesson-clickover-orientation h2,
.chapter-lesson-clickover-directory h3 {
  margin: 0;
  font-family: Georgia, "Times New Roman", serif;
  font-weight: 600;
  letter-spacing: -0.025em;
}

.chapter-lesson-clickover-orientation h2 {
  color: #fff;
  font-size: clamp(2rem, 3.5vw, 3.25rem);
}

.chapter-lesson-clickover-orientation > span {
  display: block;
  margin-top: 0.8rem;
  color: #dce6f0;
  font-family: Georgia, "Times New Roman", serif;
  font-size: 0.86rem;
  line-height: 1.5;
}

.chapter-lesson-clickover-orientation > a {
  min-height: 2.2rem;
  display: inline-flex;
  align-items: center;
  margin-top: 1.1rem;
  padding: 0.45rem 0.7rem;
  border: 1px solid rgba(255, 255, 255, 0.72);
  border-radius: 0.2rem;
  color: #fff;
  font-size: 0.73rem;
  font-weight: 800;
  text-decoration: none;
}

.chapter-lesson-clickover-orientation > a:hover {
  background: #fff;
  color: var(--chapter-navy);
}

.chapter-lesson-clickover-directory {
  min-width: 0;
  overflow-y: auto;
}

.chapter-lesson-clickover-directory > header {
  position: sticky;
  top: 0;
  z-index: 2;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  padding: 0.85rem 1rem;
  border-bottom: 1px solid var(--chapter-line);
  background: rgba(255, 253, 249, 0.96);
}

.chapter-lesson-clickover-directory header p {
  color: var(--chapter-accent);
}

.chapter-lesson-clickover-directory h3 {
  color: var(--chapter-ink);
  font-size: 1.25rem;
}

.chapter-lesson-clickover-directory header button {
  border: 0;
  background: transparent;
  color: var(--chapter-accent);
  font-size: 0.76rem;
  font-weight: 800;
  text-decoration: underline;
  text-underline-offset: 0.18em;
  cursor: pointer;
}

.chapter-lesson-clickover-list .chapter-clickover-row,
.flow-authoring-canonical .chapter-lesson-clickover-list .chapter-clickover-row {
  width: 100%;
  max-width: none;
  padding: 0.72rem 1rem;
}

/* Throwaway comparison control: shown only on a prototype-named route. */
.chapter-prototype-switcher {
  position: fixed;
  left: 50%;
  bottom: max(1rem, env(safe-area-inset-bottom));
  z-index: 90;
  width: min(25rem, calc(100vw - 2rem));
  min-height: 4.2rem;
  display: grid;
  grid-template-columns: 3.2rem minmax(0, 1fr) 3.2rem;
  align-items: stretch;
  overflow: hidden;
  border: 1px solid rgba(255, 255, 255, 0.18);
  border-radius: 999px;
  background: #16283d;
  color: #fff;
  box-shadow: 0 1rem 3rem rgba(22, 40, 61, 0.35);
  transform: translateX(-50%);
}

.chapter-prototype-switcher button {
  border: 0;
  background: rgba(255, 255, 255, 0.08);
  color: #fff;
  font-family: Georgia, "Times New Roman", serif;
  font-size: 1.35rem;
  cursor: pointer;
}

.chapter-prototype-switcher button:hover {
  background: rgba(255, 255, 255, 0.16);
}

.chapter-prototype-switcher div {
  min-width: 0;
  display: grid;
  align-content: center;
  justify-items: center;
  padding: 0.55rem;
  text-align: center;
}

.chapter-prototype-switcher strong {
  overflow: hidden;
  color: #fff;
  font-size: 0.78rem;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.chapter-prototype-switcher span {
  margin-top: 0.15rem;
  color: #c8d4e2;
  font-size: 0.64rem;
}

@media (max-width: 980px) {
  .chapter-overview-main--path {
    grid-template-columns: minmax(15rem, 0.62fr) minmax(25rem, 1.38fr);
    gap: 2.2rem;
  }

  .chapter-overview-main--index {
    grid-template-columns: minmax(15rem, 0.48fr) minmax(30rem, 1.52fr);
  }

  .chapter-index-row {
    grid-template-columns: 2.6rem minmax(8rem, 0.75fr) minmax(13rem, 1.25fr);
  }

  .chapter-index-action {
    grid-column: 2 / -1;
    display: flex;
    justify-content: flex-end;
  }

  .chapter-map-board {
    grid-template-columns: 1fr;
  }

  .chapter-map-board-heading {
    padding: 0 0 1.5rem;
    border-right: 0;
    border-bottom: 1px solid var(--chapter-line);
  }
}

@media (max-width: 720px) {
  .chapter-prototype-shell {
    padding-bottom: 6.4rem;
  }

  .chapter-prototype-flag {
    min-height: 1.65rem;
    font-size: 0.59rem;
  }

  .chapter-edition-navigation {
    justify-content: flex-start;
    min-height: 2.45rem;
    padding-inline: 0.85rem;
    overflow-x: auto;
    font-size: 0.78rem;
    white-space: nowrap;
  }

  .chapter-site-header {
    min-height: 5rem;
    padding: 0.9rem 1rem;
  }

  .chapter-site-brand {
    font-size: 1.4rem;
  }

  .chapter-site-tools span {
    display: none;
  }

  .chapter-site-tools a {
    font-size: 0.75rem;
  }

  .chapter-strip {
    grid-template-columns: repeat(5, minmax(7.7rem, 1fr));
    padding-inline: 0;
  }

  .chapter-strip-item,
  .chapter-strip-current {
    min-width: 7.7rem;
  }

  .chapter-strip-current {
    grid-template-columns: minmax(0, 1fr);
    gap: 0.12rem;
  }

  .chapter-strip-current span:last-child {
    grid-column: 1;
  }

  .chapter-overview-main h1 {
    font-size: clamp(3.4rem, 19vw, 5.1rem);
  }

  .chapter-overview-main--path,
  .chapter-overview-main--index,
  .chapter-map-introduction,
  .chapter-map-board,
  .chapter-map-group {
    grid-template-columns: minmax(0, 1fr);
  }

  .chapter-overview-main--path {
    gap: 3.5rem;
    padding: 2.8rem 1rem;
  }

  .chapter-path-introduction {
    position: static;
  }

  .chapter-path-item {
    grid-template-columns: 2.3rem minmax(0, 1fr);
    gap: 0.65rem;
  }

  .chapter-lesson-heading-row,
  .chapter-lesson-footer {
    align-items: flex-start;
    flex-direction: column;
  }

  .chapter-lesson-footer {
    display: flex;
  }

  .chapter-index-orientation-inner {
    position: static;
    padding: 2.8rem 1rem;
  }

  .chapter-index-orientation {
    border-right: 0;
  }

  .chapter-index-directory {
    padding: 2.5rem 1rem;
  }

  .chapter-index-heading-row {
    align-items: flex-start;
    flex-direction: column;
  }

  .chapter-index-row {
    grid-template-columns: 2.35rem minmax(0, 1fr);
    gap: 0.65rem;
    align-items: start;
  }

  .chapter-index-target,
  .chapter-index-action {
    grid-column: 2;
  }

  .chapter-index-action {
    justify-content: flex-start;
    flex-wrap: wrap;
  }

  .chapter-index-row:has(a:hover),
  .chapter-index-row:has(a:focus-visible) {
    margin-inline: 0;
    padding-inline: 0;
  }

  .chapter-overview-main--map {
    padding: 2.8rem 1rem;
  }

  .chapter-map-introduction {
    gap: 2rem;
  }

  .chapter-map-introduction .chapter-promise {
    padding: 1rem 0 0;
    border-top: 0.18rem solid var(--chapter-accent);
    border-left: 0;
  }

  .chapter-map-board {
    padding: 1.25rem;
  }

  .chapter-map-group {
    gap: 1rem;
  }

  .chapter-map-lesson-topline,
  .chapter-map-lesson-footer {
    align-items: flex-start;
  }

  .chapter-map-lesson-footer {
    flex-direction: column;
  }

  .chapter-clickover-backdrop {
    align-items: end;
    padding: 4rem 0 0;
  }

  .chapter-clickover {
    max-height: calc(100dvh - 3.5rem);
    border-inline: 0;
  }

  .chapter-clickover-list .chapter-clickover-row {
    grid-template-columns: 1.5rem minmax(0, 1fr) auto;
    padding-inline: 0.9rem;
  }

  .chapter-clickover-list .chapter-clickover-state {
    display: none;
  }

  .chapter-clickover-current .chapter-clickover-row {
    position: relative;
    padding-bottom: 1.6rem !important;
  }

  .chapter-clickover-current .chapter-clickover-state {
    position: absolute;
    left: 3.05rem;
    bottom: 0.38rem;
    display: block;
  }

  .chapter-clickover-current .chapter-route-status {
    display: none;
  }

  .chapter-clickover-promise,
  .chapter-clickover-header,
  .chapter-clickover-footer {
    padding-inline: 0.9rem;
  }

  .chapter-lesson-clickover {
    max-height: calc(100dvh - 7.25rem);
    grid-template-columns: minmax(0, 1fr);
  }

  .chapter-lesson-clickover-orientation {
    padding: 1rem;
  }

  .chapter-lesson-clickover-orientation h2 {
    font-size: 2rem;
  }

  .chapter-lesson-clickover-orientation > span {
    display: none;
  }

  .chapter-lesson-clickover-orientation > a {
    margin-top: 0.75rem;
  }

  .chapter-lesson-clickover-directory {
    min-height: 0;
  }

  .chapter-lesson-clickover-list .chapter-clickover-row {
    grid-template-columns: 1.5rem minmax(0, 1fr) auto;
  }

  .chapter-lesson-clickover-list .chapter-clickover-state {
    display: none;
  }

  .chapter-lesson-clickover-list .chapter-clickover-current .chapter-clickover-state {
    display: block;
  }

  .chapter-prototype-switcher {
    min-height: 3.9rem;
    grid-template-columns: 2.8rem minmax(0, 1fr) 2.8rem;
  }
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }

  .chapter-index-row,
  [data-variant="path"] .chapter-overview-main--path,
  [data-variant="index"] .chapter-overview-main--index,
  [data-variant="map"] .chapter-overview-main--map {
    animation: none;
  }
}

[data-variant="path"] .chapter-overview-main--path,
[data-variant="index"] .chapter-overview-main--index,
[data-variant="map"] .chapter-overview-main--map {
  animation: chapter-variant-arrive 180ms ease-out;
}

@keyframes chapter-variant-arrive {
  from { opacity: 0; transform: translateY(0.35rem); }
  to { opacity: 1; transform: translateY(0); }
}