.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

.module-intro {
  color: #fff;
  background-color: var(--blue-deep);
  border-bottom: 3px solid var(--gold-bright);
}

.module-intro-inner {
  display: flex;
  min-height: 198px;
  align-items: center;
  justify-content: space-between;
  padding-block: 35px;
  gap: 48px;
}

.module-intro .eyebrow {
  color: #f1c872;
}

.module-intro h1 {
  margin-bottom: 10px;
  color: #fff;
  font-size: 36px;
}

.module-intro p:last-child {
  max-width: 700px;
  margin-bottom: 0;
  color: #c9dbe8;
  font-size: 16px;
}

.intro-summary {
  display: grid;
  width: min(320px, 34vw);
  flex: 0 0 auto;
  padding: 18px 20px;
  border-left: 3px solid var(--gold-bright);
  background: rgba(255, 255, 255, 0.08);
}

.intro-summary span,
.intro-summary small {
  color: #bdd2e1;
  font-size: 12px;
}

.intro-summary strong {
  margin-block: 5px;
  font-family: "Songti SC", "SimSun", serif;
  font-size: 20px;
}

.learning-band {
  padding-block: 34px;
  background: rgba(255, 253, 248, 0.76);
  border-bottom: 1px solid var(--line);
}

.learning-workspace {
  overflow: hidden;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--surface);
  box-shadow: var(--shadow);
}

.workspace-heading {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  padding: 25px 28px 22px;
  gap: 32px;
}

.workspace-heading h2 {
  margin: 14px 0 6px;
  color: var(--blue-deep);
  font-size: 27px;
}

.workspace-heading p {
  margin: 0;
  color: var(--ink-soft);
}

.workspace-meta {
  display: grid;
  justify-items: end;
  color: var(--ink-soft);
  font-size: 12px;
  gap: 8px;
}

.verified-state {
  display: inline-flex;
  min-height: 28px;
  align-items: center;
  padding: 3px 10px;
  color: var(--success);
  background: #edf6f0;
  border: 1px solid #bad7c6;
  border-radius: 4px;
  gap: 6px;
}

.ancient-stepper {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  border-block: 1px solid var(--line);
  background: #f1ede4;
}

.ancient-stepper button {
  position: relative;
  display: grid;
  min-height: 84px;
  grid-template-columns: 34px 1fr;
  grid-template-rows: auto auto;
  align-content: center;
  padding: 14px 20px;
  color: var(--ink-soft);
  text-align: left;
  background: transparent;
  border: 0;
  border-right: 1px solid var(--line);
  cursor: pointer;
  gap: 0 10px;
}

.ancient-stepper button:last-child {
  border-right: 0;
}

.ancient-stepper button::after {
  position: absolute;
  right: 0;
  bottom: -1px;
  left: 0;
  height: 3px;
  content: "";
  background: var(--gold);
  transform: scaleX(0);
  transition: transform 180ms ease;
}

.ancient-stepper button > span {
  display: grid;
  width: 32px;
  height: 32px;
  grid-row: 1 / 3;
  place-items: center;
  align-self: center;
  color: var(--blue-deep);
  border: 1px solid #aab8c3;
  border-radius: 50%;
  font-family: Georgia, serif;
  font-weight: 700;
}

.ancient-stepper button strong {
  color: var(--ink);
  font-size: 15px;
}

.ancient-stepper button small {
  font-size: 11px;
}

.ancient-stepper button[aria-selected="true"] {
  color: var(--blue-deep);
  background: var(--surface);
}

.ancient-stepper button[aria-selected="true"]::after {
  transform: scaleX(1);
}

.ancient-stepper button[aria-selected="true"] > span {
  color: #fff;
  background: var(--blue-deep);
  border-color: var(--blue-deep);
}

.ancient-stepper button:disabled {
  cursor: not-allowed;
  opacity: 0.58;
}

.ancient-stepper button:disabled > span {
  color: #7d7b75;
  background: #e4e0d8;
  border-color: #c7c1b7;
}

.workspace-controls {
  display: flex;
  align-items: flex-end;
  padding: 18px 28px;
  background: #fbf8f1;
  border-bottom: 1px solid var(--line);
  gap: 28px;
}

.view-switch,
.tutor-path-switch {
  padding: 0;
  margin: 0;
  border: 0;
}

.view-switch legend,
.tutor-path-switch legend {
  padding: 0;
  margin-bottom: 6px;
  color: var(--ink-soft);
  font-size: 11px;
  font-weight: 700;
}

.view-switch > div {
  display: flex;
  padding: 3px;
  background: #e9e5dc;
  border-radius: 6px;
}

.view-switch button {
  min-height: 34px;
  padding: 5px 13px;
  color: var(--ink-soft);
  background: transparent;
  border: 0;
  border-radius: 4px;
  cursor: pointer;
  font-size: 13px;
}

.view-switch button[aria-pressed="true"] {
  color: var(--blue-deep);
  background: var(--surface-strong);
  box-shadow: 0 2px 7px rgba(44, 40, 32, 0.09);
  font-weight: 800;
}

.control-note {
  display: flex;
  align-items: center;
  margin: 0 0 7px auto;
  color: var(--ink-soft);
  font-size: 11px;
  gap: 7px;
}

.control-note span,
.hint-policy span {
  display: grid;
  width: 18px;
  height: 18px;
  flex: 0 0 auto;
  place-items: center;
  color: #fff;
  background: var(--blue);
  border-radius: 50%;
  font-family: Georgia, serif;
  font-size: 11px;
  font-weight: 700;
}

.variant-gate {
  display: grid;
  grid-template-columns: 42px minmax(0, 1fr) auto;
  align-items: center;
  padding: 15px 28px;
  background: #edf4f7;
  border-bottom: 1px solid #c5d8e2;
  gap: 14px;
}

.variant-gate-symbol {
  display: grid;
  width: 38px;
  height: 38px;
  place-items: center;
  color: #fff;
  background: var(--blue-deep);
  border-radius: 50%;
  font-family: "STKaiti", "KaiTi", serif;
}

.variant-gate strong {
  color: var(--blue-deep);
}

.variant-gate p {
  margin: 2px 0 0;
  color: var(--ink-soft);
  font-size: 12px;
}

.variant-gate .button {
  min-height: 38px;
}

.step-panel {
  min-height: 430px;
  padding: 30px 32px;
}

.panel-kicker {
  margin-bottom: 6px;
  color: var(--gold);
  font-size: 11px;
  font-weight: 800;
}

.panel-heading {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  margin-bottom: 24px;
  gap: 22px;
}

.panel-heading h2,
.panel-heading h3 {
  margin: 0;
  color: var(--blue-deep);
}

.path-status,
.draft-state {
  display: inline-flex;
  min-height: 28px;
  align-items: center;
  padding: 3px 10px;
  color: #315b78;
  background: #eaf3f7;
  border: 1px solid #c2dbe8;
  border-radius: 4px;
  font-size: 11px;
}

.read-layout {
  display: grid;
  grid-template-columns: minmax(0, 1.35fr) minmax(280px, 0.65fr);
  gap: 24px;
}

.reading-stage {
  min-height: 335px;
  padding: 20px;
  background: #f2e7d1;
  border: 1px solid #dac29a;
}

.classical-paper {
  display: flex;
  min-height: 270px;
  align-items: stretch;
  justify-content: center;
  padding: 6px 18px;
  background-color: #f6ecd7;
  background-image: repeating-linear-gradient(90deg, transparent 0, transparent 64px, rgba(130, 86, 36, 0.08) 65px);
  border: 1px solid rgba(128, 80, 39, 0.2);
  box-shadow: inset 0 0 36px rgba(117, 70, 23, 0.08);
  gap: 4px;
}

.classical-segment {
  width: 64px;
  min-height: 252px;
  padding: 15px 16px;
  color: #40301f;
  background: transparent;
  border: 1px solid transparent;
  border-radius: 3px;
  cursor: pointer;
  font-family: "STKaiti", "KaiTi", serif;
  font-size: 18px;
  line-height: 1.7;
  text-align: start;
  writing-mode: vertical-rl;
  text-orientation: upright;
  transition: background 160ms ease, border-color 160ms ease;
}

.classical-segment:hover,
.classical-segment.active {
  background: rgba(183, 123, 41, 0.12);
  border-color: rgba(183, 123, 41, 0.4);
}

.plain-content blockquote {
  min-height: 214px;
  padding: 30px;
  margin: 0;
  color: #373b36;
  background: #fffaf0;
  border-left: 4px solid var(--gold);
  font-family: "Songti SC", "SimSun", serif;
  font-size: 20px;
  line-height: 2;
}

.quantity-clues {
  display: flex;
  flex-wrap: wrap;
  margin-top: 16px;
  gap: 8px;
}

.quantity-clues span {
  padding: 4px 10px;
  color: #4c5d68;
  background: #edf3f5;
  border: 1px solid #ccdadd;
  border-radius: 4px;
  font-size: 12px;
}

.annotation-panel {
  min-height: 335px;
  padding: 22px;
  color: #eaf1f6;
  background: var(--blue-deep);
  border-top: 3px solid var(--gold-bright);
}

.annotation-panel h3 {
  margin: 10px 0 15px;
  color: #fff;
  font-family: "Songti SC", "SimSun", serif;
  font-size: 19px;
}

.annotation-translation {
  min-height: 64px;
  color: #d5e3ed;
}

.annotation-note {
  padding-top: 16px;
  border-top: 1px solid rgba(255, 255, 255, 0.16);
}

.annotation-note strong {
  color: #f4ca76;
  font-size: 12px;
}

.annotation-note p {
  margin: 7px 0 0;
  color: #bed0dc;
  font-size: 13px;
}

.source-note {
  padding: 10px 13px;
  margin: 18px 0 0;
  color: #675f50;
  background: #f8f2e6;
  border-left: 3px solid var(--gold);
  font-size: 12px;
}

.method-visual {
  display: grid;
  grid-template-columns: 96px minmax(60px, 1fr) 150px minmax(60px, 1fr) 96px;
  align-items: center;
  max-width: 800px;
  margin: 18px auto 34px;
  text-align: center;
}

.method-visual span,
.method-visual b {
  display: grid;
  min-height: 68px;
  place-items: center;
  padding: 10px;
  border: 1px solid #d1b980;
  background: #fbf2df;
  font-family: "Songti SC", "SimSun", serif;
  font-size: 18px;
}

.method-visual b {
  color: #fff;
  background: var(--blue-deep);
  border-color: var(--blue-deep);
}

.method-visual i {
  height: 1px;
  background: var(--gold);
}

.method-visual.modern span {
  color: #1f5a7d;
  background: #eaf4f8;
  border-color: #b8d5e3;
}

.method-steps {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  padding: 0;
  margin: 0;
  list-style: none;
  gap: 14px;
}

.method-steps li {
  display: grid;
  grid-template-columns: 34px 1fr;
  min-height: 112px;
  align-content: start;
  padding: 17px;
  background: #fbf8f1;
  border: 1px solid var(--line);
  border-top: 3px solid var(--gold);
  gap: 11px;
}

.method-steps li > span {
  display: grid;
  width: 30px;
  height: 30px;
  place-items: center;
  color: #fff;
  background: var(--blue-deep);
  border-radius: 50%;
  font-family: Georgia, serif;
  font-size: 13px;
}

.method-steps p {
  margin: 2px 0 0;
}

.compare-head,
.compare-rows li {
  display: grid;
  grid-template-columns: 1fr 80px 1fr;
  align-items: center;
  gap: 12px;
}

.compare-head {
  margin-bottom: 8px;
  color: var(--ink-soft);
  font-size: 12px;
  font-weight: 800;
  text-align: center;
}

.compare-rows {
  display: grid;
  padding: 0;
  margin: 0;
  list-style: none;
  gap: 10px;
}

.compare-rows li > p {
  display: grid;
  min-height: 86px;
  grid-template-columns: 28px 1fr;
  align-items: center;
  padding: 14px;
  margin: 0;
  color: var(--ink-soft);
  background: #f6f3ec;
  border: 1px solid var(--line);
  gap: 10px;
  transition: border-color 160ms ease, background 160ms ease;
}

.compare-rows li > p.is-focus {
  color: var(--ink);
  background: #eef5f8;
  border-color: #87b4cc;
  box-shadow: inset 3px 0 0 var(--blue);
}

.compare-rows p > span {
  display: grid;
  width: 26px;
  height: 26px;
  place-items: center;
  color: var(--blue-deep);
  border: 1px solid #9ab5c5;
  border-radius: 50%;
  font-size: 12px;
  font-weight: 800;
}

.compare-rows li > i {
  color: var(--gold);
  font-size: 24px;
  font-style: normal;
  text-align: center;
}

.comparison-note {
  margin: 16px 0 0;
  color: var(--ink-soft);
  font-size: 12px;
  text-align: center;
}

.compare-next-row {
  padding-top: 18px;
  margin-top: 18px;
  border-top: 1px solid var(--line);
}

.compare-next-row > span {
  margin-right: auto;
  color: var(--ink-soft);
  font-size: 12px;
}

.compare-next-row a[aria-disabled="true"] {
  pointer-events: none;
  opacity: 0.62;
}

.variant-layout {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(360px, 0.75fr);
  align-items: center;
  min-height: 280px;
  gap: 48px;
}

.variant-layout h3 {
  color: var(--blue-deep);
  font-family: "Songti SC", "SimSun", serif;
  font-size: 23px;
}

.variant-question {
  padding: 18px 20px;
  color: #4b321a;
  background: #f8edd6;
  border-left: 4px solid var(--gold);
  font-family: "Songti SC", "SimSun", serif;
  font-size: 18px;
}

.variant-guidance {
  color: var(--ink-soft);
  font-size: 13px;
}

.variant-form {
  padding: 24px;
  background: #f3f7f8;
  border: 1px solid #cbdce4;
}

.variant-form label,
.answer-label {
  display: block;
  margin-bottom: 8px;
  color: var(--blue-deep);
  font-weight: 800;
}

.answer-row {
  display: flex;
  gap: 9px;
}

.answer-row input {
  min-width: 0;
  flex: 1;
  padding: 9px 12px;
  border: 1px solid #aebfc9;
  border-radius: 5px;
  background: #fff;
}

.form-feedback {
  min-height: 24px;
  margin: 10px 0 0;
  font-size: 13px;
}

.form-feedback.success { color: var(--success); }
.form-feedback.warning { color: var(--warning); }
.form-feedback.error { color: var(--danger); }

.next-action-row,
.step-navigation {
  display: flex;
  align-items: center;
  justify-content: flex-end;
  gap: 10px;
}

.next-action-row {
  padding-top: 22px;
  border-top: 1px solid var(--line);
}

.step-navigation {
  justify-content: space-between;
  min-height: 72px;
  padding: 14px 28px;
  background: #f7f3eb;
  border-top: 1px solid var(--line);
}

.step-navigation > span {
  color: var(--ink-soft);
  font-size: 12px;
}

.review-state {
  display: grid;
  grid-template-columns: 84px 1fr;
  min-height: 265px;
  align-items: center;
  padding: 30px;
  background: var(--surface);
  border: 1px solid var(--line);
  border-left: 4px solid var(--gold);
  gap: 28px;
}

.review-state h2 {
  color: var(--blue-deep);
}

.review-state p {
  max-width: 820px;
  color: var(--ink-soft);
}

.review-symbol {
  display: grid;
  width: 72px;
  height: 72px;
  place-items: center;
  color: #fff;
  background: var(--blue-deep);
  border: 2px solid var(--gold-bright);
  border-radius: 7px;
  font-family: "STKaiti", "KaiTi", serif;
  font-size: 30px;
}

.review-checks {
  display: flex;
  flex-wrap: wrap;
  margin: 14px 0 20px;
  gap: 8px;
}

.review-checks span {
  padding: 4px 10px;
  color: #77531e;
  background: #f8edd7;
  border: 1px solid #dfc18b;
  border-radius: 4px;
  font-size: 12px;
}

.task-library {
  padding-block: 45px 70px;
}

.library-heading {
  display: flex;
  align-items: flex-end;
  justify-content: space-between;
  margin-bottom: 22px;
  gap: 30px;
}

.library-heading h2 {
  color: var(--blue-deep);
}

.library-heading p {
  margin: 0;
  color: var(--ink-soft);
}

.filter-result {
  flex: 0 0 auto;
  font-size: 12px;
}

.chapter-filters {
  display: flex;
  flex-wrap: wrap;
  padding: 10px;
  margin-bottom: 22px;
  background: rgba(255, 253, 248, 0.74);
  border-block: 1px solid var(--line);
  gap: 8px;
}

.chapter-filters button {
  min-height: 36px;
  padding: 6px 15px;
  color: var(--ink-soft);
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 18px;
  cursor: pointer;
}

.chapter-filters button[aria-pressed="true"] {
  color: #fff;
  background: var(--blue-deep);
  border-color: var(--blue-deep);
  font-weight: 800;
}

.task-card-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 18px;
}

.ancient-task-card {
  overflow: hidden;
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 8px;
  box-shadow: 0 8px 22px rgba(50, 42, 28, 0.06);
}

.ancient-task-card.current {
  border-color: #719ab4;
  box-shadow: 0 0 0 2px rgba(22, 127, 192, 0.12), 0 8px 22px rgba(50, 42, 28, 0.07);
}

.task-card-image {
  position: relative;
  display: block;
  aspect-ratio: 3 / 2;
  overflow: hidden;
  background: #d9d4c8;
}

.task-card-image .responsive-art {
  display: block;
  width: 100%;
  height: 100%;
}

.task-card-image img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform 220ms ease;
}

.task-card-image:hover img {
  transform: scale(1.025);
}

.content-state {
  position: absolute;
  top: 12px;
  right: 12px;
  padding: 4px 9px;
  color: #fff;
  background: var(--blue-deep);
  border-radius: 4px;
  font-size: 11px;
  font-weight: 800;
}

.content-state.reviewing {
  color: #5f4215;
  background: #f1ce83;
}

.content-state.verified {
  color: #164c3a;
  background: #d8eee3;
  border: 1px solid #8db9a3;
}

.resource-kind {
  color: #315468;
  background: #edf4f7;
  border-color: #bfd2dc;
}

.task-card-body {
  padding: 17px;
}

.task-card-body h3 {
  margin: 13px 0 7px;
  color: var(--blue-deep);
}

.task-card-body > p {
  min-height: 48px;
  margin-bottom: 15px;
  color: var(--ink-soft);
  font-size: 13px;
}

.task-card-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding-top: 12px;
  border-top: 1px solid #e7e0d3;
  gap: 10px;
}

.task-card-footer > span {
  color: var(--ink-soft);
  font-size: 11px;
}

.task-card-footer .text-link {
  font-size: 12px;
}

.task-empty {
  padding: 35px;
  color: var(--ink-soft);
  background: var(--surface);
  border: 1px dashed var(--line);
  text-align: center;
}

/* Tutor */
.tutor-rule {
  display: flex;
  width: min(350px, 36vw);
  flex: 0 0 auto;
  align-items: center;
  padding: 15px 18px;
  background: rgba(255, 255, 255, 0.08);
  border-left: 3px solid var(--gold-bright);
  gap: 13px;
}

.tutor-rule > span {
  display: grid;
  width: 43px;
  height: 43px;
  flex: 0 0 auto;
  place-items: center;
  color: var(--blue-deep);
  background: #f2ca77;
  border-radius: 50%;
  font-family: "STKaiti", "KaiTi", serif;
  font-size: 21px;
}

.tutor-rule div {
  display: grid;
}

.tutor-rule small {
  color: #c6d8e4;
  font-size: 11px;
}

.tutor-page {
  padding-block: 34px 70px;
}

.tutor-context {
  padding: 24px 26px;
  margin-bottom: 18px;
  background: #f9eed8;
  border: 1px solid #dfc691;
  border-left: 4px solid var(--gold);
}

.tutor-context-head {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 18px;
}

.tutor-context h2 {
  color: var(--blue-deep);
}

.no-answer-badge {
  display: inline-flex;
  flex: 0 0 auto;
  align-items: center;
  padding: 4px 9px;
  color: #3e654e;
  background: #edf5ef;
  border: 1px solid #bad3c2;
  border-radius: 4px;
  font-size: 11px;
  font-weight: 800;
  gap: 5px;
}

.tutor-question {
  max-width: 990px;
  color: #493821;
  font-family: "Songti SC", "SimSun", serif;
  font-size: 18px;
  line-height: 1.9;
}

.context-tools {
  display: flex;
  align-items: center;
  padding-top: 14px;
  border-top: 1px solid rgba(128, 80, 39, 0.18);
  gap: 10px;
}

.context-tools label {
  color: var(--ink-soft);
  font-size: 12px;
  font-weight: 700;
}

.context-tools select {
  min-height: 44px;
  min-width: 240px;
  padding: 7px 35px 7px 10px;
  background: var(--surface);
  border: 1px solid #c5b896;
  border-radius: 5px;
}

.context-tools .button {
  min-height: 44px;
}

.tutor-grid {
  display: grid;
  grid-template-columns: minmax(0, 1.32fr) minmax(370px, 0.68fr);
  align-items: start;
  gap: 18px;
}

.answer-workspace,
.hint-workspace {
  min-width: 0;
  padding: 25px;
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 8px;
  box-shadow: 0 8px 24px rgba(50, 42, 28, 0.06);
}

.answer-workspace .panel-heading {
  margin-bottom: 20px;
}

.tutor-path-switch {
  margin-bottom: 22px;
}

.tutor-path-switch > div {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 10px;
}

.tutor-path-switch button {
  display: grid;
  min-height: 76px;
  grid-template-columns: 39px 1fr;
  grid-template-rows: auto auto;
  align-content: center;
  padding: 11px 13px;
  color: var(--ink-soft);
  text-align: left;
  background: #f7f4ed;
  border: 1px solid var(--line);
  border-radius: 6px;
  cursor: pointer;
  gap: 0 10px;
}

.tutor-path-switch button > span {
  display: grid;
  width: 36px;
  height: 36px;
  grid-row: 1 / 3;
  place-items: center;
  color: var(--blue-deep);
  border: 1px solid #9db2c0;
  border-radius: 50%;
  font-family: "STKaiti", "KaiTi", serif;
  font-size: 17px;
}

.tutor-path-switch button strong {
  color: var(--ink);
  font-size: 13px;
}

.tutor-path-switch button small {
  font-size: 10px;
}

.tutor-path-switch button small b {
  font: inherit;
  font-weight: 800;
}

.tutor-path-switch button:disabled {
  cursor: wait;
  opacity: 0.68;
}

.tutor-path-switch button[aria-pressed="true"] {
  color: #2e5f7f;
  background: #eaf4f8;
  border-color: #79abc5;
  box-shadow: inset 3px 0 0 var(--blue);
}

.tutor-path-switch button[aria-pressed="true"] > span {
  color: #fff;
  background: var(--blue-deep);
  border-color: var(--blue-deep);
}

.latex-toolbar {
  display: flex;
  min-height: 43px;
  align-items: center;
  padding: 5px 7px;
  background: #ece9e2;
  border: 1px solid #c9c3b8;
  border-bottom: 0;
  border-radius: 6px 6px 0 0;
  gap: 4px;
}

.latex-toolbar > span {
  padding-inline: 5px 10px;
  color: var(--ink-soft);
  font-size: 11px;
  font-weight: 700;
}

.latex-toolbar button {
  display: grid;
  width: 32px;
  height: 31px;
  padding: 0;
  place-items: center;
  color: var(--blue-deep);
  background: var(--surface-strong);
  border: 1px solid #c9c3b8;
  border-radius: 4px;
  cursor: pointer;
  font-family: Georgia, "Times New Roman", serif;
  font-weight: 700;
}

.latex-toolbar button:hover {
  background: #edf5f8;
  border-color: var(--blue);
}

#tutor-reasoning,
#tutor-formula {
  display: block;
  width: 100%;
  padding: 15px;
  resize: vertical;
  color: var(--ink);
  background: #fff;
  border: 1px solid #aeb8bd;
  border-radius: 6px;
  line-height: 1.75;
}

.tutor-variable-select {
  display: block;
  width: 100%;
  min-height: 46px;
  padding: 10px 38px 10px 13px;
  color: var(--ink);
  background: #fff;
  border: 1px solid #aeb8bd;
  border-radius: 6px;
}

.reasoning-label {
  margin-top: 19px;
}

#tutor-reasoning {
  min-height: 130px;
}

.formula-label {
  margin-top: 19px;
}

#tutor-formula {
  min-height: 78px;
  border-radius: 0;
  font-family: Consolas, "Courier New", monospace;
}

#tutor-reasoning:focus,
#tutor-formula:focus,
.tutor-variable-select:focus {
  border-color: var(--blue);
  outline: 3px solid rgba(22, 127, 192, 0.15);
}

#tutor-formula[aria-invalid="true"] {
  border-color: var(--danger);
  background: #fff8f7;
}

.formula-preview-wrap {
  display: grid;
  grid-template-columns: 82px minmax(0, 1fr);
  min-height: 66px;
  align-items: center;
  padding: 9px 12px;
  background: #f3f7f8;
  border: 1px solid #b9cbd4;
  border-top: 0;
  border-radius: 0 0 6px 6px;
  gap: 10px;
}

.formula-preview-wrap > span {
  color: var(--ink-soft);
  font-size: 11px;
  font-weight: 800;
}

#formula-preview {
  display: flex;
  min-width: 0;
  min-height: 42px;
  align-items: center;
  overflow-x: auto;
  color: var(--blue-deep);
  font-family: Cambria, "Times New Roman", serif;
  font-size: 20px;
  white-space: pre-wrap;
  gap: 4px;
}

#formula-preview math {
  font-size: 1.15em;
}

#formula-preview.invalid {
  color: var(--danger);
  font-family: inherit;
  font-size: 12px;
}

.preview-placeholder {
  color: #878b88;
  font-family: inherit;
  font-size: 12px;
}

.math-fraction {
  display: inline-grid;
  min-width: 26px;
  grid-template-rows: auto auto;
  align-items: center;
  text-align: center;
  vertical-align: middle;
}

.math-numerator {
  padding: 0 4px 2px;
  border-bottom: 1px solid currentColor;
}

.math-denominator {
  padding: 2px 4px 0;
}

.formula-help {
  margin: 6px 0 0;
  color: var(--ink-soft);
  font-size: 10px;
}

.answer-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-top: 14px;
  gap: 20px;
}

.answer-footer p {
  margin: 0;
  color: var(--ink-soft);
  font-size: 11px;
}

.tutor-feedback {
  padding: 14px 16px;
  margin-top: 16px;
  border-left: 4px solid var(--blue);
  background: #eef5f8;
}

.tutor-feedback strong {
  color: var(--blue-deep);
}

.tutor-feedback p {
  margin: 4px 0 0;
  color: var(--ink-soft);
  font-size: 13px;
}

.tutor-feedback.success {
  background: #edf6f0;
  border-left-color: var(--success);
}

.tutor-feedback.success strong { color: var(--success); }
.tutor-feedback.error { background: #faeeee; border-left-color: var(--danger); }
.tutor-feedback.error strong { color: var(--danger); }

.tutor-next-actions {
  display: flex;
  align-items: center;
  padding-top: 16px;
  margin-top: 16px;
  border-top: 1px solid var(--line);
  gap: 13px;
}

.tutor-next-actions > span {
  color: var(--ink-soft);
  font-size: 11px;
}

.hint-workspace {
  position: sticky;
  top: 126px;
}

.hint-heading {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 15px;
}

.hint-heading h2 {
  margin-bottom: 0;
  color: var(--blue-deep);
  font-size: 21px;
}

.hint-heading > span {
  flex: 0 0 auto;
  color: var(--ink-soft);
  font-size: 11px;
}

.hint-meter {
  height: 5px;
  overflow: hidden;
  margin: 17px 0 20px;
  background: #ddd8cd;
  border-radius: 3px;
}

.active-path-note {
  margin: 12px 0 0;
  color: var(--blue-deep);
  font-size: 11px;
  font-weight: 800;
}

.hint-workspace[aria-busy="true"] .hint-list {
  opacity: 0.55;
}

.hint-meter span {
  display: block;
  height: 100%;
  background: var(--gold);
  transition: width 220ms ease;
}

.hint-list {
  display: grid;
  padding: 0;
  margin: 0;
  list-style: none;
  gap: 10px;
}

.hint-tier {
  display: grid;
  grid-template-columns: 35px 1fr;
  padding: 13px;
  color: #8b877d;
  background: #f3f1ec;
  border: 1px solid #ddd8cf;
  border-radius: 6px;
  gap: 10px;
}

.hint-tier.unlocked {
  color: var(--ink);
  background: #fffaf0;
  border-color: #d6bb83;
}

.hint-tier-index {
  display: grid;
  width: 30px;
  height: 30px;
  place-items: center;
  color: #8b877d;
  border: 1px solid #c9c4ba;
  border-radius: 50%;
  font-family: Georgia, serif;
  font-weight: 800;
}

.hint-tier.unlocked .hint-tier-index {
  color: #fff;
  background: var(--gold);
  border-color: var(--gold);
}

.hint-tier-head {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 8px;
}

.hint-tier h3 {
  margin: 4px 0 5px;
  font-size: 13px;
}

.hint-lock {
  flex: 0 0 auto;
  margin-top: 3px;
  font-size: 10px;
}

.hint-tier.unlocked .hint-lock {
  color: var(--success);
  font-weight: 800;
}

.hint-body,
.hint-locked-copy {
  margin: 0;
  font-size: 12px;
}

.hint-body {
  color: #604a2c;
}

.hint-locked-copy {
  color: #98938a;
}

.review-modeling {
  padding: 13px;
  margin-top: 12px;
  background: #edf4f7;
  border-left: 3px solid var(--blue);
}

.review-modeling p {
  margin-bottom: 7px;
  color: var(--ink-soft);
  font-size: 11px;
}

.review-modeling .text-link {
  font-size: 12px;
}

.hint-policy {
  display: flex;
  align-items: flex-start;
  margin: 17px 0 0;
  color: var(--ink-soft);
  font-size: 10px;
  gap: 7px;
}

@media (max-width: 1080px) {
  .task-card-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .read-layout,
  .tutor-grid {
    grid-template-columns: minmax(0, 1fr);
  }

  .annotation-panel {
    min-height: auto;
  }

  .hint-workspace {
    position: static;
  }

  .hint-list {
    grid-template-columns: repeat(3, 1fr);
  }

  .hint-tier {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 820px) {
  .module-intro-inner {
    min-height: 170px;
    padding-block: 25px;
  }

  .module-intro h1 {
    font-size: 30px;
  }

  .module-intro p:last-child {
    font-size: 14px;
  }

  .intro-summary,
  .tutor-rule {
    display: none;
  }

  .learning-band {
    padding-block: 20px;
  }

  .workspace-heading,
  .workspace-controls,
  .step-panel {
    padding-right: 18px;
    padding-left: 18px;
  }

  .workspace-heading {
    display: grid;
  }

  .workspace-meta {
    grid-template-columns: auto auto;
    justify-content: start;
    justify-items: start;
  }

  .ancient-stepper button {
    min-height: 70px;
    grid-template-columns: 28px 1fr;
    padding: 9px;
    gap: 0 6px;
  }

  .ancient-stepper button > span {
    width: 26px;
    height: 26px;
  }

  .ancient-stepper button small {
    display: none;
  }

  .workspace-controls {
    align-items: flex-start;
    flex-wrap: wrap;
    gap: 13px;
  }

  .view-switch button,
  .chapter-filters button {
    min-height: 44px;
  }

  .latex-toolbar button {
    width: 44px;
    height: 44px;
  }

  .variant-gate {
    grid-template-columns: 38px 1fr;
    padding-inline: 18px;
  }

  .variant-gate .button {
    grid-column: 2;
    width: max-content;
  }

  .control-note {
    width: 100%;
    margin: 0;
  }

  .method-steps,
  .hint-list {
    grid-template-columns: 1fr;
  }

  .method-visual {
    grid-template-columns: 72px 1fr 110px 1fr 72px;
  }

  .method-visual span,
  .method-visual b {
    min-height: 58px;
    padding: 6px;
    font-size: 14px;
  }

  .variant-layout {
    grid-template-columns: 1fr;
    gap: 18px;
  }

  .task-library {
    padding-block: 35px 45px;
  }

  .chapter-filters {
    flex-wrap: nowrap;
    overflow-x: auto;
    scrollbar-width: thin;
  }

  .chapter-filters button {
    flex: 0 0 auto;
  }

  .context-tools {
    align-items: stretch;
    flex-wrap: wrap;
  }

  .context-tools label {
    width: 100%;
  }

  .context-tools select {
    min-width: 0;
    flex: 1;
  }
}

@media (max-width: 600px) {
  .module-intro-inner {
    min-height: 150px;
  }

  .module-intro h1 {
    font-size: 27px;
  }

  .learning-workspace {
    width: calc(100% - 20px);
  }

  .workspace-heading h2 {
    font-size: 23px;
  }

  .workspace-meta {
    grid-template-columns: 1fr;
  }

  .ancient-stepper {
    overflow-x: auto;
    grid-template-columns: repeat(4, minmax(105px, 1fr));
  }

  .workspace-controls {
    display: grid;
  }

  .view-switch > div {
    width: 100%;
  }

  .view-switch button {
    flex: 1;
  }

  .step-panel {
    min-height: 390px;
    padding-top: 22px;
    padding-bottom: 22px;
  }

  .reading-stage {
    min-height: auto;
    padding: 13px;
  }

  .classical-paper {
    display: grid;
    min-height: auto;
    padding: 8px;
    background-image: repeating-linear-gradient(0deg, transparent 0, transparent 48px, rgba(130, 86, 36, 0.08) 49px);
  }

  .classical-segment {
    width: 100%;
    min-height: 48px;
    padding: 9px 11px;
    font-size: 17px;
    text-align: left;
    writing-mode: horizontal-tb;
  }

  .latex-toolbar button {
    width: 44px;
    height: 44px;
  }

  .plain-content blockquote {
    min-height: 180px;
    padding: 20px;
    font-size: 17px;
  }

  .panel-heading {
    display: grid;
  }

  .method-visual {
    grid-template-columns: 65px 1fr 94px 1fr 65px;
    margin-bottom: 22px;
  }

  .method-visual span,
  .method-visual b {
    min-height: 52px;
    font-size: 12px;
  }

  .compare-head {
    display: none;
  }

  .compare-rows li {
    grid-template-columns: 1fr;
  }

  .compare-rows li > i {
    height: 24px;
    transform: rotate(90deg);
  }

  .variant-form {
    padding: 16px;
  }

  .answer-row,
  .next-action-row {
    align-items: stretch;
    flex-direction: column;
  }

  .step-navigation {
    padding-inline: 14px;
  }

  .step-navigation > span {
    display: none;
  }

  .review-state {
    grid-template-columns: 1fr;
    padding: 22px;
  }

  .library-heading {
    display: grid;
  }

  .task-card-grid {
    grid-template-columns: 1fr;
  }

  .tutor-page {
    width: calc(100% - 20px);
    padding-top: 20px;
  }

  .tutor-context,
  .answer-workspace,
  .hint-workspace {
    padding: 18px;
  }

  .tutor-context-head {
    display: grid;
  }

  .tutor-question {
    font-size: 16px;
  }

  .context-tools {
    display: grid;
  }

  .tutor-path-switch > div {
    grid-template-columns: 1fr;
  }

  .latex-toolbar {
    overflow-x: auto;
  }

  .formula-preview-wrap {
    grid-template-columns: 1fr;
  }

  .latex-toolbar > span,
  .latex-toolbar button {
    flex: 0 0 auto;
  }

  .answer-footer,
  .tutor-next-actions {
    align-items: stretch;
    flex-direction: column;
  }
}

@media (prefers-reduced-motion: reduce) {
  .ancient-stepper button::after,
  .task-card-image img,
  .hint-meter span {
    transition: none;
  }
}

/* Round-two library and compact learning workspaces. */
.journey-artwork {
  position: relative;
  margin: 0 0 24px;
  overflow: hidden;
  border-radius: 7px;
  background: var(--blue-deep);
}

.journey-art {
  width: 100%;
  aspect-ratio: 8 / 3;
}

.journey-artwork figcaption {
  position: absolute;
  right: 0;
  bottom: 0;
  left: 0;
  padding: 18px 22px 12px;
  color: #fff;
  background: linear-gradient(transparent, rgba(18, 35, 49, .86));
  font-size: 13px;
}

.comparison-artwork {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  margin-top: 22px;
  gap: 16px;
}

.comparison-artwork figure {
  margin: 0;
  overflow: hidden;
  border: 1px solid var(--line);
  border-radius: 7px;
  background: var(--surface);
}

.comparison-art {
  width: 100%;
  aspect-ratio: 4 / 3;
}

.comparison-artwork figcaption {
  display: grid;
  padding: 12px 14px 14px;
  gap: 2px;
}

.comparison-artwork figcaption strong {
  color: var(--blue-deep);
}

.comparison-artwork figcaption span {
  color: var(--ink-soft);
  font-size: 12px;
}

.library-hero {
  color: #fff;
  background: var(--blue-deep);
  border-bottom: 3px solid var(--gold-bright);
}

.library-hero-inner {
  display: flex;
  min-height: 174px;
  align-items: center;
  justify-content: space-between;
  gap: 32px;
}

.library-hero h1 {
  margin-bottom: 6px;
  color: #fff;
}

.library-hero p:last-child {
  margin: 0;
  color: #c9dbe8;
}

.library-count {
  display: grid;
  min-width: 128px;
  text-align: center;
}

.library-count strong {
  color: #f3cd80;
  font-size: 40px;
  line-height: 1;
}

.library-count span {
  margin-top: 7px;
  color: #c9dbe8;
  font-size: 12px;
}

.library-page {
  padding-block: 32px 72px;
}

.library-filter-panel {
  padding: 24px 0 26px;
  border-bottom: 1px solid var(--line);
}

.library-search-row {
  display: grid;
  grid-template-columns: minmax(280px, 1fr) auto auto;
  align-items: end;
  gap: 10px;
}

.library-search-row label,
.library-select-filters label {
  display: grid;
  color: var(--blue-deep);
  font-size: 12px;
  font-weight: 700;
  gap: 6px;
}

.library-search-row input,
.library-select-filters select {
  width: 100%;
  min-height: 44px;
  padding: 8px 12px;
  border: 1px solid #b8b4aa;
  border-radius: 6px;
  background: #fff;
}

.library-chapter-filter {
  padding: 0;
  margin: 20px 0 16px;
  border: 0;
}

.library-chapter-filter legend {
  margin-bottom: 7px;
  color: var(--ink-soft);
  font-size: 11px;
  font-weight: 700;
}

.library-chapter-filter > div {
  display: flex;
  flex-wrap: wrap;
  gap: 7px;
}

.library-chapter-filter label {
  position: relative;
}

.library-chapter-filter input {
  position: absolute;
  width: 1px;
  height: 1px;
  opacity: 0;
}

.library-chapter-filter span {
  display: grid;
  min-width: 62px;
  min-height: 44px;
  place-items: center;
  padding: 7px 12px;
  border: 1px solid var(--line);
  border-radius: 5px;
  background: var(--surface);
  cursor: pointer;
}

.library-chapter-filter input:checked + span {
  color: #fff;
  border-color: var(--blue-deep);
  background: var(--blue-deep);
}

.library-chapter-filter input:focus-visible + span {
  outline: 3px solid rgba(22, 127, 192, 0.48);
  outline-offset: 2px;
}

.library-select-filters {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 220px));
  gap: 12px;
}

.library-results {
  padding-top: 34px;
}

.library-results-heading {
  display: flex;
  align-items: end;
  justify-content: space-between;
  margin-bottom: 20px;
  gap: 24px;
}

.library-results-heading p:last-child {
  max-width: 460px;
  margin-bottom: 0;
  color: var(--ink-soft);
  font-size: 12px;
}

.library-card-grid {
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

.library-no-results {
  display: grid;
  grid-template-columns: 54px minmax(0, 1fr) auto;
  align-items: center;
  min-height: 150px;
  padding: 24px;
  border-block: 1px solid var(--line);
  gap: 18px;
}

.library-no-results > span {
  display: grid;
  width: 50px;
  height: 50px;
  place-items: center;
  color: #fff;
  background: var(--blue-deep);
  border: 2px solid var(--gold-bright);
  border-radius: 7px;
}

.library-no-results h3,
.library-no-results p {
  margin-bottom: 0;
}

.library-active-filters {
  display: flex;
  flex-wrap: wrap;
  margin: 13px 0 0;
  gap: 7px;
}

.library-active-filters div {
  display: inline-flex;
  align-items: baseline;
  padding: 5px 8px;
  border: 1px solid #c9d4d9;
  border-radius: 4px;
  background: #f1f6f7;
  gap: 5px;
}

.library-active-filters dt {
  color: #596b73;
  font-size: 11px;
}

.library-active-filters dd {
  margin: 0;
  color: var(--blue-deep);
  font-size: 12px;
  font-weight: 800;
}

.library-no-results-actions {
  display: grid;
  justify-items: start;
  gap: 8px;
}

.library-pagination {
  display: flex;
  align-items: center;
  justify-content: center;
  margin-top: 32px;
  gap: 14px;
}

.library-pagination .disabled {
  cursor: not-allowed;
  opacity: .48;
}

.related-library {
  padding-block: 42px 72px;
}

.related-library .library-heading {
  margin-bottom: 18px;
}

.related-task-grid {
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

.variant-complete-state {
  display: grid;
  grid-template-columns: 54px minmax(0, 1fr) auto;
  min-height: 220px;
  align-items: center;
  padding: 26px;
  border: 1px solid #afd0bd;
  background: #edf6f0;
  gap: 18px;
}

.variant-complete-state > span {
  display: grid;
  width: 50px;
  height: 50px;
  place-items: center;
  color: #fff;
  background: var(--success);
  border-radius: 50%;
  font-family: "STKaiti", "KaiTi", serif;
  font-size: 21px;
}

.variant-complete-state h3,
.variant-complete-state p {
  margin-bottom: 4px;
}

.tutor-intro .module-intro-inner {
  min-height: 150px;
}

.tutor-context {
  padding-top: 18px;
  padding-bottom: 16px;
}

.tutor-question-disclosure,
.context-tools {
  border-top: 1px solid var(--line);
}

.tutor-question-disclosure summary,
.context-tools > summary {
  display: flex;
  min-height: 44px;
  align-items: center;
  justify-content: space-between;
  cursor: pointer;
  gap: 18px;
  list-style: none;
}

.tutor-question-disclosure summary::-webkit-details-marker,
.context-tools > summary::-webkit-details-marker {
  display: none;
}

.question-summary {
  display: -webkit-box;
  overflow: hidden;
  color: var(--ink);
  -webkit-box-orient: vertical;
  -webkit-line-clamp: 1;
}

.disclosure-label,
.context-tools > summary {
  color: var(--blue-deep);
  font-size: 12px;
  font-weight: 800;
}

.disclosure-label {
  flex: 0 0 auto;
}

.tutor-question {
  padding: 13px 15px;
  margin: 0 0 12px;
  font-size: 15px;
}

.context-tools {
  display: block;
  padding: 0;
  background: transparent;
}

.context-tool-body {
  display: flex;
  align-items: center;
  padding: 10px 0 2px;
  gap: 9px;
}

.context-tool-body select {
  min-height: 44px;
  flex: 1;
}

.hint-list {
  grid-template-columns: 1fr;
}

.hint-tier {
  display: block;
  padding: 0;
  overflow: hidden;
}

.hint-tier-toggle {
  display: grid;
  width: 100%;
  min-height: 58px;
  grid-template-columns: 35px minmax(0, 1fr);
  align-items: center;
  padding: 10px 12px;
  color: inherit;
  border: 0;
  background: transparent;
  text-align: left;
  cursor: pointer;
  gap: 10px;
}

.hint-tier-toggle:disabled {
  cursor: not-allowed;
}

.hint-tier-content {
  display: grid;
  min-width: 0;
}

.hint-tier-head {
  display: flex;
  justify-content: space-between;
  gap: 8px;
}

.hint-tier-head strong {
  font-size: 13px;
}

.hint-tier-panel {
  padding: 0 14px 14px 57px;
}

.hint-tier-panel .hint-body {
  padding-top: 11px;
  border-top: 1px solid rgba(183, 123, 41, .22);
}

@media (max-width: 900px) {
  .library-card-grid,
  .related-task-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

@media (max-width: 820px) {
  .journey-art {
    aspect-ratio: 4 / 5;
  }

  .journey-artwork figcaption {
    padding-inline: 16px;
  }

  .ancient-stepper {
    grid-template-columns: repeat(4, minmax(0, 1fr));
    overflow: visible;
  }

  .ancient-stepper button {
    min-width: 0;
    grid-template-columns: 26px minmax(0, 1fr);
    padding-inline: 7px;
  }

  .ancient-stepper button strong {
    overflow-wrap: anywhere;
    font-size: 13px;
  }

  .learning-workspace {
    margin-bottom: 78px;
  }

  .step-navigation {
    position: fixed;
    right: 15px;
    bottom: calc(64px + env(safe-area-inset-bottom));
    left: 15px;
    z-index: 58;
    min-height: 62px;
    padding: 9px 12px;
    border: 1px solid var(--line);
    border-radius: 7px 7px 0 0;
    box-shadow: 0 -8px 24px rgba(42, 36, 27, .12);
  }

  .step-navigation .button {
    min-width: 112px;
  }

  .library-hero-inner {
    min-height: 148px;
  }

  .library-search-row,
  .library-select-filters {
    grid-template-columns: 1fr;
  }

  .library-select-filters {
    gap: 10px;
  }

  .library-results-heading {
    display: grid;
  }
}

@media (max-width: 600px) {
  .comparison-artwork {
    grid-template-columns: 1fr;
  }

  .library-card-grid,
  .related-task-grid {
    grid-template-columns: 1fr;
  }

  .library-search-row {
    grid-template-columns: 1fr 1fr;
  }

  .library-search-row label {
    grid-column: 1 / -1;
  }

  .library-chapter-filter > div {
    display: grid;
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }

  .library-chapter-filter span {
    min-width: 0;
    min-height: 44px;
    padding-inline: 6px;
  }

  .library-count {
    display: none;
  }

  .library-no-results,
  .variant-complete-state {
    grid-template-columns: 1fr;
  }

  .variant-complete-state .button {
    width: 100%;
  }

  .context-tool-body {
    display: grid;
  }

  .hint-tier-panel {
    padding-left: 14px;
  }

  .step-navigation .button {
    min-width: 0;
    flex: 1;
  }
}

/* Verified, read-only question detail */
.question-detail-hero {
  color: #fff;
  background: #173c61;
  border-bottom: 4px solid var(--gold);
}

.question-detail-hero-inner {
  display: grid;
  min-height: 330px;
  grid-template-columns: minmax(0, 1.1fr) minmax(360px, .9fr);
  align-items: center;
  padding-block: 30px;
  gap: 42px;
}

.question-detail-heading {
  min-width: 0;
}

.question-detail-heading h1 {
  max-width: 760px;
  margin: 9px 0 10px;
  color: #fff;
  font-size: 40px;
}

.question-detail-heading .eyebrow {
  margin: 20px 0 0;
  color: #e8c579;
}

.question-detail-subtitle {
  max-width: 720px;
  margin-bottom: 17px;
  color: #d7e4eb;
  font-size: 16px;
}

.detail-back-link {
  display: inline-flex;
  min-height: 44px;
  align-items: center;
  color: #e1ebf1;
  font-size: 13px;
  font-weight: 700;
  gap: 7px;
}

.question-detail-heading .tag-row {
  margin-top: 10px;
}

.verified-tag {
  color: #173f32;
  background: #d8eee3;
  border-color: #8db9a3;
}

.question-detail-meta {
  display: flex;
  flex-wrap: wrap;
  color: #d5e3eb;
  font-size: 12px;
  gap: 8px;
}

.question-detail-meta span {
  padding-right: 9px;
  border-right: 1px solid rgba(255, 255, 255, .28);
}

.question-detail-meta span:last-child {
  padding-right: 0;
  border-right: 0;
}

.question-detail-art {
  min-width: 0;
  margin: 0;
}

.detail-responsive-art {
  aspect-ratio: 3 / 2;
  border: 1px solid rgba(255, 255, 255, .25);
  border-radius: 6px;
}

.detail-responsive-art img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.question-detail-art figcaption {
  padding-top: 7px;
  color: #becfda;
  font-size: 11px;
}

.question-detail-page {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(280px, 350px);
  padding-block: 42px 80px;
  gap: 24px 34px;
}

.question-reading-panel,
.question-review-panel,
.worked-solution-panel {
  min-width: 0;
}

.question-reading-panel {
  padding: 4px 0 32px;
  border-bottom: 1px solid var(--line);
}

.question-reading-panel > header {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 20px;
}

.question-reading-panel h2,
.question-review-panel h2,
.worked-solution-panel h2 {
  color: var(--blue-deep);
}

.read-only-mark {
  flex: 0 0 auto;
  padding: 5px 9px;
  color: #315468;
  background: #edf4f7;
  border: 1px solid #bfd2dc;
  border-radius: 4px;
  font-size: 11px;
  font-weight: 800;
}

.question-prompt {
  padding: 23px 25px;
  margin: 15px 0 18px;
  color: #3d3426;
  background: #fffdf8;
  border-block: 1px solid #dfd2bd;
  border-left: 4px solid var(--gold);
  font-family: "Songti SC", "SimSun", serif;
  font-size: 19px;
  line-height: 1.9;
}

.unit-notes,
.solution-verification {
  display: grid;
  grid-template-columns: 92px minmax(0, 1fr);
  padding: 14px 16px;
  background: #edf4f7;
  border-left: 3px solid #6b9bb6;
  gap: 12px;
}

.unit-notes strong,
.solution-verification strong {
  color: var(--blue-deep);
}

.unit-notes ul,
.solution-verification ul {
  padding-left: 18px;
  margin: 0;
}

.question-review-panel {
  align-self: start;
  padding: 22px 0 22px 24px;
  border-left: 1px solid var(--line);
}

.question-review-panel > p:not(.eyebrow),
.solution-intro > p:last-child {
  color: var(--ink-soft);
  font-size: 13px;
}

.question-review-panel dl {
  margin: 22px 0;
}

.question-review-panel dl > div {
  display: grid;
  grid-template-columns: 78px minmax(0, 1fr);
  padding-block: 9px;
  border-bottom: 1px solid #e2dacd;
  gap: 9px;
}

.question-review-panel dt {
  color: var(--ink-soft);
  font-size: 11px;
}

.question-review-panel dd {
  min-width: 0;
  margin: 0;
  overflow-wrap: anywhere;
  font-size: 12px;
  font-weight: 700;
}

.source-warning {
  padding: 14px;
  color: #5f451d;
  background: #f8edd7;
  border: 1px solid #dfc18b;
  border-radius: 5px;
}

.source-warning p {
  margin: 5px 0 0;
  font-size: 12px;
}

.worked-solution-panel {
  grid-column: 1 / -1;
  padding-top: 14px;
}

.solution-intro {
  margin-bottom: 16px;
}

.worked-solution {
  overflow: hidden;
  background: var(--surface);
  border: 1px solid #cbbd9f;
  border-radius: 6px;
}

.worked-solution summary {
  position: relative;
  display: grid;
  min-height: 68px;
  grid-template-columns: minmax(0, 1fr) auto;
  align-items: center;
  padding: 13px 58px 13px 20px;
  color: var(--blue-deep);
  cursor: pointer;
  list-style: none;
}

.worked-solution summary::-webkit-details-marker {
  display: none;
}

.worked-solution summary::after {
  position: absolute;
  right: 20px;
  display: grid;
  width: 30px;
  height: 30px;
  place-items: center;
  content: "+";
  color: #fff;
  background: var(--blue-deep);
  border-radius: 50%;
  font-size: 21px;
}

.worked-solution[open] summary::after {
  content: "−";
}

.worked-solution summary span {
  font-weight: 800;
}

.worked-solution summary small {
  color: var(--ink-soft);
  font-size: 11px;
}

.worked-solution-body {
  padding: 24px;
  border-top: 1px solid var(--line);
}

.solution-summary {
  display: grid;
  grid-template-columns: 70px minmax(0, 1fr);
  padding: 15px 17px;
  color: #234b3d;
  background: #edf6f0;
  border-left: 4px solid var(--success);
  gap: 12px;
}

.solution-steps {
  display: grid;
  padding: 0;
  margin: 23px 0;
  list-style: none;
  gap: 12px;
}

.solution-steps li {
  display: grid;
  grid-template-columns: 34px minmax(0, 1fr);
  align-items: start;
  gap: 12px;
}

.solution-steps li > span {
  display: grid;
  width: 32px;
  height: 32px;
  place-items: center;
  color: #fff;
  background: var(--blue-deep);
  border-radius: 50%;
  font-family: Georgia, serif;
  font-weight: 800;
}

.solution-steps p {
  padding-top: 4px;
  margin: 0;
}

.ratio-visual,
.math-diagram {
  padding-top: 18px;
  margin: 18px 0 0;
  border-top: 1px solid var(--line);
}

.ratio-visual figcaption {
  display: grid;
  margin-bottom: 12px;
}

.ratio-visual figcaption span {
  color: var(--ink-soft);
  font-size: 11px;
}

.ratio-visual > div {
  display: grid;
  gap: 7px;
}

.ratio-visual > div span {
  display: flex;
  width: calc(var(--ratio) * 2%);
  min-width: 74px;
  min-height: 34px;
  align-items: center;
  padding-inline: 12px;
  color: #fff;
  background: #3d718e;
  border-left: 4px solid var(--gold-bright);
  font-weight: 800;
}

.math-diagram {
  color: var(--ink-soft);
}

.math-diagram svg {
  width: min(100%, 720px);
  height: auto;
  margin-inline: auto;
  background: #f8fbfc;
  border: 1px solid #c8d8e1;
}

.math-diagram text {
  fill: #284a5e;
  font-family: "Microsoft YaHei", sans-serif;
  font-size: 16px;
}

.diagram-water {
  fill: #dcecf2;
  stroke: #6a9bb4;
  stroke-width: 2;
}

.diagram-line,
.diagram-accent,
.diagram-angle {
  fill: none;
  stroke: #244c65;
  stroke-width: 4;
}

.diagram-accent {
  stroke: #b77b29;
}

.diagram-angle {
  stroke-width: 2;
}

.question-detail-actions {
  display: flex;
  grid-column: 1 / -1;
  justify-content: flex-end;
  padding-top: 4px;
  gap: 10px;
}

@media (max-width: 900px) {
  .question-detail-hero-inner {
    grid-template-columns: minmax(0, 1fr) minmax(280px, .8fr);
    gap: 24px;
  }

  .question-detail-page {
    grid-template-columns: minmax(0, 1fr);
  }

  .question-review-panel {
    grid-row: 2;
    padding: 20px 0;
    border-top: 1px solid var(--line);
    border-left: 0;
  }
}

@media (max-width: 820px) {
  .question-detail-hero-inner {
    grid-template-columns: minmax(0, 1fr);
    padding-block: 20px 25px;
  }

  .question-detail-heading h1 {
    font-size: 31px;
  }

  .question-detail-art {
    max-width: none;
  }

  .detail-responsive-art {
    aspect-ratio: 4 / 5;
    max-height: 330px;
  }

  .question-detail-page {
    width: calc(100% - 32px);
    padding-block: 28px calc(88px + env(safe-area-inset-bottom));
  }

  .question-reading-panel > header,
  .question-detail-actions {
    align-items: stretch;
    flex-direction: column;
  }

  .read-only-mark {
    width: max-content;
  }

  .question-prompt {
    padding: 18px;
    font-size: 17px;
  }

  .unit-notes,
  .solution-verification,
  .solution-summary {
    grid-template-columns: minmax(0, 1fr);
  }

  .worked-solution summary {
    grid-template-columns: minmax(0, 1fr);
  }

  .worked-solution summary small {
    display: block;
  }

  .worked-solution-body {
    padding: 18px;
  }

  .question-detail-actions .button {
    width: 100%;
  }
}

/* Round-three tutor orientation and task-driven condition board. */
.tutor-location {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 180px;
  gap: 28px;
  align-items: center;
  padding: 28px 0;
  border-bottom: 1px solid var(--line);
}

.tutor-location-copy > h2 {
  margin: 2px 0 6px;
  font-size: 24px;
}

.tutor-location-copy > p:not(.eyebrow) {
  margin: 0;
  color: var(--ink-soft);
}

.tutor-location-copy > p span {
  color: var(--blue-deep);
  font-weight: 700;
}

.tutor-location-art {
  overflow: hidden;
  aspect-ratio: 4 / 3;
  border: 1px solid var(--line);
  border-radius: 6px;
  background: #e8e1d4;
}

.tutor-context-art,
.tutor-location-art picture,
.tutor-location-art img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.tutor-completion-list {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 10px;
  padding: 0;
  margin: 18px 0 0;
  list-style: none;
}

.tutor-completion-list button {
  display: grid;
  grid-template-columns: 18px minmax(0, 1fr);
  width: 100%;
  min-height: 56px;
  padding: 9px 10px;
  color: var(--ink);
  text-align: left;
  border: 1px solid var(--line);
  border-radius: 6px;
  background: var(--surface);
  cursor: pointer;
}

.tutor-completion-list button > span {
  grid-row: 1 / span 2;
  width: 16px;
  height: 16px;
  margin-top: 3px;
  border: 2px solid #7b786e;
  border-radius: 50%;
}

.tutor-completion-list strong {
  font-size: 14px;
}

.tutor-completion-list small {
  color: var(--ink-soft);
  font-size: 12px;
}

.tutor-completion-list li.complete button {
  border-color: rgba(47, 119, 87, 0.45);
  background: rgba(47, 119, 87, 0.06);
}

.tutor-completion-list li.complete button > span {
  border-color: var(--success);
  background: var(--success);
  box-shadow: inset 0 0 0 3px var(--surface);
}

.tutor-condition-board {
  display: grid;
  grid-template-columns: minmax(170px, 0.7fr) minmax(0, 1.8fr);
  gap: 18px 24px;
  margin-top: 18px;
  padding: 18px 0 4px;
  border-top: 1px solid var(--line);
}

.condition-board-heading h3 {
  margin: 3px 0 0;
  font-size: 18px;
}

.tutor-condition-board ul {
  display: grid;
  gap: 8px;
  padding: 0;
  margin: 0;
  list-style: none;
}

.tutor-condition-board li {
  display: grid;
  grid-template-columns: minmax(70px, auto) minmax(0, 1fr);
  gap: 12px;
  align-items: baseline;
  padding: 10px 12px;
  border-left: 3px solid var(--blue);
  background: rgba(23, 60, 97, 0.055);
}

.tutor-condition-board li span {
  color: var(--blue-deep);
  font-size: 13px;
  font-weight: 700;
}

.tutor-condition-board li strong {
  font-size: 14px;
}

.tutor-condition-board > p {
  grid-column: 2;
  margin: -8px 0 0;
  color: var(--ink-soft);
  font-size: 13px;
}

.ai-guidance {
  margin: 12px 0;
  padding: 12px 14px;
  border-left: 3px solid var(--blue);
  background: rgba(22, 127, 192, 0.07);
}

.ai-guidance span {
  display: block;
  margin-bottom: 4px;
  color: var(--blue-deep);
  font-size: 12px;
  font-weight: 700;
}

.ai-guidance p {
  margin: 0;
  color: var(--ink);
  font-size: 14px;
}

.reasoning-evidence {
  display: grid;
  gap: 8px;
  margin: 12px 0 18px;
  padding: 14px;
  border: 1px solid var(--line);
  border-radius: 6px;
}

.reasoning-evidence[hidden] {
  display: none;
}

.reasoning-evidence legend {
  padding: 0 6px;
  color: var(--ink-soft);
  font-size: 13px;
  font-weight: 700;
}

.reasoning-evidence label {
  display: flex;
  min-height: 44px;
  gap: 10px;
  align-items: center;
  font-size: 14px;
}

.reasoning-evidence input {
  width: 18px;
  height: 18px;
  flex: 0 0 auto;
}

@media (max-width: 820px) {
  .tutor-location {
    grid-template-columns: minmax(0, 1fr) 132px;
    gap: 18px;
    padding: 22px 0;
  }

  .tutor-completion-list {
    grid-template-columns: 1fr;
  }

  .tutor-completion-list button {
    min-height: 52px;
  }

  .tutor-condition-board {
    grid-template-columns: 1fr;
  }

  .tutor-condition-board > p {
    grid-column: 1;
    margin-top: -6px;
  }
}

@media (max-width: 560px) {
  .tutor-location {
    grid-template-columns: 1fr;
  }

  .tutor-location-art {
    width: min(100%, 240px);
  }

  .tutor-location-copy > h2 {
    font-size: 21px;
  }

  .tutor-condition-board li {
    grid-template-columns: 1fr;
    gap: 2px;
  }
}