:root {
  color-scheme: light dark;

  &:has(> head > meta[name="color-scheme"][content="dark"]) {
    color-scheme: dark;
  }
  &:has(> head > meta[name="color-scheme"][content="light"]) {
    color-scheme: light;
  }

  --bg-page: light-dark(#f4f7fb, #0d131c);
  --bg-surface: light-dark(#ffffff, #151e2b);
  --bg-subtle: light-dark(#eaf0f7, #1c2838);
  --text-primary: light-dark(#101828, #f2f6fc);
  --text-secondary: light-dark(#475467, #b2c0d4);
  --border-subtle: light-dark(#cbd5e1, #324156);
  --border-strong: light-dark(#64748b, #6f84a3);

  --accent: light-dark(#0b5cab, #58a6ff);
  --accent-contrast: light-dark(#ffffff, #08121e);
  --accent-soft: light-dark(#e6f0fb, #172d47);

  --success-text: light-dark(#065f46, #6ee7b7);
  --success-bg: light-dark(#ecfdf5, #0e2e24);
  --success-border: light-dark(#059669, #34d399);

  --error-text: light-dark(#991b1b, #fca5a5);
  --error-bg: light-dark(#fef2f2, #38161a);
  --error-border: light-dark(#dc2626, #f87171);

  --flag-text: light-dark(#92400e, #fcd34d);
  --flag-bg: light-dark(#fffbeb, #33260e);
  --flag-border: light-dark(#d97706, #f59e0b);

  --focus-ring: light-dark(#0b5cab, #79c0ff);
  --radius-md: 10px;
  --radius-lg: 14px;
}

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

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Inter, sans-serif;
  line-height: 1.5;
  background-color: var(--bg-page);
  color: var(--text-primary);
}

.visually-hidden:where(:not(:focus-within, :active)) {
  position: absolute !important;
  clip-path: inset(50%) !important;
  overflow: hidden !important;
  width: 1px !important;
  height: 1px !important;
  margin: -1px !important;
  padding: 0 !important;
  border: 0 !important;
  white-space: nowrap !important;
}

.skip-link:focus {
  position: fixed;
  top: 0.75rem;
  left: 0.75rem;
  z-index: 100;
  padding: 0.625rem 1rem;
  background: var(--accent);
  color: var(--accent-contrast);
  border-radius: var(--radius-md);
  font-weight: 600;
  text-decoration: none;
}

:where(a:any-link, button, select, input):focus-visible {
  outline: 3px solid var(--focus-ring);
  outline-offset: 2px;
}

/* Theme toggle label visibility without relying on JS classes */
.theme-label-dark {
  display: none;
}
@media (prefers-color-scheme: dark) {
  .theme-label-light { display: none; }
  .theme-label-dark { display: inline; }
}
:root:has(> head > meta[name="color-scheme"][content="dark"]) {
  .theme-label-light { display: none; }
  .theme-label-dark { display: inline; }
}
:root:has(> head > meta[name="color-scheme"][content="light"]) {
  .theme-label-light { display: inline; }
  .theme-label-dark { display: none; }
}

.site-header {
  background: var(--bg-surface);
  border-bottom: 1px solid var(--border-subtle);
}

.header-inner {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0.875rem max(1.25rem, env(safe-area-inset-right)) 0.875rem max(1.25rem, env(safe-area-inset-left));
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 0.75rem;
}

.btn-sm {
  min-block-size: 2.25rem;
  padding: 0.35rem 0.75rem;
  font-size: 0.84rem;
}

.auth-status-group {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.user-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.25rem 0.25rem 0.25rem 0.75rem;
  background: var(--bg-subtle);
  border: 1px solid var(--border-subtle);
  border-radius: 999px;
}

.user-name {
  font-size: 0.84rem;
  font-weight: 600;
  max-width: 160px;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.primary-nav {
  border-top: 1px solid var(--border-subtle);
  background: var(--bg-surface);
}

.primary-nav-inner {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 max(1.25rem, env(safe-area-inset-left));
  display: flex;
  gap: 0.25rem;
  overflow-x: auto;
}

.nav-tab {
  min-block-size: 2.75rem;
  padding: 0.5rem 1rem;
  border: 0;
  border-bottom: 3px solid transparent;
  background: transparent;
  color: var(--text-secondary);
  font-weight: 600;
  font-size: 0.92rem;
  cursor: pointer;
  white-space: nowrap;
}

.nav-tab[aria-selected="true"] {
  color: var(--accent);
  border-bottom-color: var(--accent);
}

.brand {
  display: flex;
  align-items: center;
  gap: 0.85rem;
}

.brand-badge {
  display: grid;
  place-items: center;
  width: 2.5rem;
  height: 2.5rem;
  border-radius: var(--radius-md);
  background: var(--accent);
  color: var(--accent-contrast);
  font-weight: 800;
  font-size: 1rem;
}

.brand-kicker {
  margin: 0;
  font-size: 0.8rem;
  color: var(--text-secondary);
  font-weight: 600;
}

.site-title {
  margin: 0;
  font-size: 1.35rem;
  line-height: 1.25;
}

.header-actions {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.main-shell {
  max-width: 1200px;
  margin: 0 auto;
  padding: 1.25rem;
}

.controls-bar {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  margin-bottom: 1.25rem;
  padding: 0.875rem 1rem;
  background: var(--bg-surface);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
}

.mode-switch {
  display: inline-flex;
  background: var(--bg-subtle);
  padding: 0.25rem;
  border-radius: var(--radius-md);
  gap: 0.25rem;
}

.filter-group {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.field-label {
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--text-secondary);
}

.select-input {
  min-block-size: 2.5rem;
  padding: 0.375rem 0.75rem;
  border-radius: var(--radius-md);
  border: 1px solid var(--border-strong);
  background: var(--bg-surface);
  color: var(--text-primary);
  font-size: 0.9rem;
}

.stats-pill-group {
  display: flex;
  flex-wrap: wrap;
  gap: 0.625rem;
}

.stat-pill {
  display: flex;
  align-items: baseline;
  gap: 0.4rem;
  padding: 0.375rem 0.75rem;
  background: var(--bg-subtle);
  border: 1px solid var(--border-subtle);
  border-radius: 999px;
  font-size: 0.875rem;
}

.stat-label {
  color: var(--text-secondary);
}

.workspace-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 300px;
  gap: 1.25rem;
  align-items: start;
}

@media (max-width: 900px) {
  .workspace-grid {
    grid-template-columns: 1fr;
  }
}

.scope-banner {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  gap: 0.5rem;
  margin-bottom: 0.75rem;
  padding: 0.5rem 0.875rem;
  background: var(--accent-soft);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  font-size: 0.85rem;
  font-weight: 500;
}

.scope-note {
  color: var(--text-secondary);
}

.card {
  background: var(--bg-surface);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  padding: 1.5rem;
}

.question-meta {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.5rem;
  margin-bottom: 1rem;
}

.meta-badge {
  padding: 0.2rem 0.65rem;
  border-radius: 999px;
  background: var(--accent-soft);
  color: var(--accent);
  font-weight: 700;
  font-size: 0.82rem;
}

.meta-category {
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--text-secondary);
}

.meta-page {
  font-size: 0.82rem;
  color: var(--text-secondary);
  margin-right: auto;
}

.question-stem {
  margin: 0 0 1.25rem;
  font-size: 1.15rem;
  font-weight: 600;
  line-height: 1.45;
}

.options-fieldset {
  border: 0;
  padding: 0;
  margin: 0;
}

.options-list {
  display: flex;
  flex-direction: column;
  gap: 0.625rem;
}

.option-label {
  display: flex;
  align-items: flex-start;
  gap: 0.75rem;
  min-block-size: 3rem;
  padding: 0.85rem 1rem;
  border: 1.5px solid var(--border-subtle);
  border-radius: var(--radius-md);
  background: var(--bg-surface);
  cursor: pointer;
  transition: border-color 0.15s ease, background-color 0.15s ease;
}

.option-label:hover {
  border-color: var(--border-strong);
  background: var(--bg-subtle);
}

.option-label:has(input:checked) {
  border-color: var(--accent);
  background: var(--accent-soft);
}

.option-label.is-correct {
  border-color: var(--success-border);
  background: var(--success-bg);
  color: var(--success-text);
}

.option-label.is-incorrect {
  border-color: var(--error-border);
  background: var(--error-bg);
  color: var(--error-text);
}

.option-radio {
  margin-top: 0.25rem;
  accent-color: var(--accent);
  inline-size: 1.1rem;
  block-size: 1.1rem;
  flex-shrink: 0;
}

.option-key {
  font-weight: 700;
  min-inline-size: 1.25rem;
}

.option-text {
  flex: 1;
}

.option-badge {
  font-weight: 700;
  font-size: 0.85rem;
  white-space: nowrap;
}

.feedback-box {
  margin-top: 1.25rem;
  padding: 1rem 1.125rem;
  border-radius: var(--radius-md);
  border-left: 4px solid var(--border-strong);
  background: var(--bg-subtle);
}

.feedback-box.is-correct {
  border-left-color: var(--success-border);
  background: var(--success-bg);
}

.feedback-box.is-incorrect {
  border-left-color: var(--error-border);
  background: var(--error-bg);
}

.feedback-header {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  margin-bottom: 0.4rem;
}

.feedback-rationale {
  margin: 0 0 0.5rem;
  font-size: 0.95rem;
}

.feedback-pearl {
  margin: 0;
  font-size: 0.88rem;
  color: var(--text-secondary);
  font-weight: 500;
}

.question-actions {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  align-items: center;
  gap: 0.75rem;
  margin-top: 1.5rem;
  padding-top: 1rem;
  border-top: 1px solid var(--border-subtle);
}

.action-right {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.35rem;
  min-block-size: 2.5rem;
  min-inline-size: 2.5rem;
  padding: 0.5rem 1rem;
  border-radius: var(--radius-md);
  border: 1px solid transparent;
  font-size: 0.9rem;
  font-weight: 600;
  cursor: pointer;
  background: transparent;
  color: var(--text-primary);
}

.btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

.btn-primary {
  background: var(--accent);
  color: var(--accent-contrast);
}

.btn-secondary {
  border-color: var(--border-strong);
  background: var(--bg-surface);
}

.btn-accent {
  background: var(--success-border);
  color: #ffffff;
}

.btn-danger {
  background: var(--error-border);
  color: #ffffff;
}

.btn-ghost {
  border-color: var(--border-subtle);
}

.btn-tab[aria-pressed="true"] {
  background: var(--bg-surface);
  border-color: var(--border-subtle);
  box-shadow: 0 1px 2px rgb(0 0 0 / 0.08);
}

.btn-flag {
  min-block-size: 2rem;
  padding: 0.25rem 0.65rem;
  border-color: var(--border-subtle);
  font-size: 0.82rem;
}

.btn-flag[aria-pressed="true"] {
  background: var(--flag-bg);
  color: var(--flag-text);
  border-color: var(--flag-border);
}

.nav-card {
  padding: 1.125rem;
}

.nav-header {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  margin-bottom: 0.875rem;
}

.nav-title {
  margin: 0;
  font-size: 1rem;
}

.keyboard-hint {
  font-size: 0.75rem;
  color: var(--text-secondary);
}

.question-grid {
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: 0.45rem;
}

.q-chip {
  position: relative;
  min-block-size: 2.35rem;
  min-inline-size: 2.35rem;
  border-radius: 8px;
  border: 1.5px solid var(--border-subtle);
  background: var(--bg-surface);
  color: var(--text-primary);
  font-weight: 600;
  font-size: 0.85rem;
  cursor: pointer;
}

.q-chip[aria-current="step"] {
  border-color: var(--accent);
  box-shadow: 0 0 0 2px var(--accent-soft);
}

.q-chip.is-answered {
  background: var(--accent-soft);
  border-color: var(--accent);
}

.q-chip.is-correct {
  background: var(--success-bg);
  border-color: var(--success-border);
  color: var(--success-text);
}

.q-chip.is-incorrect {
  background: var(--error-bg);
  border-color: var(--error-border);
  color: var(--error-text);
}

.q-chip.is-flagged::after {
  content: "";
  position: absolute;
  top: 3px;
  right: 3px;
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--flag-border);
}

.legend-list {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  margin-top: 1rem;
  padding-top: 0.75rem;
  border-top: 1px solid var(--border-subtle);
  font-size: 0.78rem;
  color: var(--text-secondary);
}

.legend-item {
  display: inline-flex;
  align-items: center;
  gap: 0.3rem;
}

.dot {
  width: 10px;
  height: 10px;
  border-radius: 3px;
  border: 1px solid var(--border-strong);
}

.dot-current { border-color: var(--accent); background: var(--accent-soft); }
.dot-correct { border-color: var(--success-border); background: var(--success-bg); }
.dot-incorrect { border-color: var(--error-border); background: var(--error-bg); }
.dot-flagged { border-color: var(--flag-border); background: var(--flag-border); }

/* Native Modal Dialogs */
dialog {
  max-width: 560px;
  width: calc(100% - 2rem);
  padding: 0;
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  background: var(--bg-surface);
  color: var(--text-primary);
}

dialog:modal {
  overscroll-behavior: contain;
}

dialog::backdrop {
  background: rgb(15 23 42 / 0.55);
  overflow: hidden;
  overscroll-behavior: contain;
}

.dialog-shell {
  padding: 1.5rem;
}

.dialog-title {
  margin: 0 0 0.75rem;
  font-size: 1.2rem;
}

.dialog-body {
  margin: 0 0 1.25rem;
  color: var(--text-secondary);
}

.results-summary {
  padding: 1rem;
  border-radius: var(--radius-md);
  background: var(--bg-subtle);
  margin-bottom: 1rem;
}

.results-breakdown {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
  margin-bottom: 1.25rem;
}

.breakdown-row {
  display: flex;
  justify-content: space-between;
  padding: 0.5rem 0.75rem;
  border: 1px solid var(--border-subtle);
  border-radius: 8px;
  font-size: 0.9rem;
}

.dialog-actions {
  display: flex;
  justify-content: flex-end;
  gap: 0.5rem;
}

@media (forced-colors: active) {
  .option-label:has(input:checked),
  .q-chip[aria-current="step"] {
    outline: 2px solid Highlight;
  }
}

.custom-active-banner {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 0.75rem;
  margin-bottom: 1rem;
  padding: 0.65rem 1rem;
  border-radius: var(--radius-md);
  background: var(--flag-bg);
  border: 1px solid var(--flag-border);
  color: var(--flag-text);
  font-weight: 600;
  font-size: 0.9rem;
}

.section-heading {
  margin: 0 0 0.4rem;
  font-size: 1.2rem;
}

.subsection-heading {
  margin: 1.5rem 0 0.75rem;
  font-size: 1rem;
}

.section-subtitle {
  margin: 0 0 1.25rem;
  color: var(--text-secondary);
  font-size: 0.95rem;
}

.preset-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(210px, 1fr));
  gap: 0.75rem;
  margin-bottom: 1.5rem;
}

.preset-btn {
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  gap: 0.25rem;
  min-block-size: 4.5rem;
  padding: 0.9rem 1rem;
  border-radius: var(--radius-md);
  border: 1.5px solid var(--border-subtle);
  background: var(--bg-subtle);
  color: var(--text-primary);
  text-align: left;
  cursor: pointer;
}

.preset-btn:hover {
  border-color: var(--accent);
  background: var(--accent-soft);
}

.preset-btn span {
  font-size: 0.84rem;
  color: var(--text-secondary);
}

.custom-form {
  display: flex;
  flex-direction: column;
  gap: 1.25rem;
  padding-top: 1.25rem;
  border-top: 1px solid var(--border-subtle);
}

.custom-fieldset {
  border: 0;
  padding: 0;
  margin: 0;
}

.checkbox-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 0.5rem;
  margin-top: 0.5rem;
}

.checkbox-inline {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  min-block-size: 2.5rem;
  font-size: 0.92rem;
  cursor: pointer;
}

.checkbox-inline input {
  inline-size: 1.1rem;
  block-size: 1.1rem;
  accent-color: var(--accent);
}

.custom-row {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 1.25rem;
}

.history-layout {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.25rem;
  align-items: start;
}

@media (max-width: 860px) {
  .history-layout {
    grid-template-columns: 1fr;
  }
}

.kpi-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 0.75rem;
  margin-top: 1rem;
}

.kpi-box {
  padding: 0.875rem 1rem;
  border-radius: var(--radius-md);
  background: var(--bg-subtle);
  border: 1px solid var(--border-subtle);
}

.kpi-box span {
  display: block;
  font-size: 0.8rem;
  color: var(--text-secondary);
}

.kpi-box strong {
  font-size: 1.35rem;
}

.topic-mastery-list {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.topic-row {
  display: flex;
  flex-direction: column;
  gap: 0.3rem;
}

.topic-row-head {
  display: flex;
  justify-content: space-between;
  font-size: 0.88rem;
  font-weight: 600;
}

.progress-track {
  height: 8px;
  border-radius: 999px;
  background: var(--bg-subtle);
  overflow: hidden;
}

.progress-fill {
  height: 100%;
  background: var(--accent);
  border-radius: 999px;
}

.history-header {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  align-items: baseline;
  gap: 0.5rem;
  margin-bottom: 1rem;
}

.history-list {
  display: flex;
  flex-direction: column;
  gap: 0.65rem;
}

.history-item {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  align-items: center;
  gap: 0.75rem;
  padding: 0.85rem 1rem;
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  background: var(--bg-subtle);
}

.history-item-meta {
  font-size: 0.82rem;
  color: var(--text-secondary);
}

/* Auth Dialog */
.dialog-header-row {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 0.5rem;
  margin-bottom: 0.5rem;
}

.btn-google {
  width: 100%;
  min-block-size: 2.75rem;
  background: var(--bg-surface);
  border: 1.5px solid var(--border-strong);
  font-weight: 700;
}

.btn-google:hover {
  background: var(--bg-subtle);
}

.auth-divider {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  margin: 1rem 0;
  color: var(--text-secondary);
  font-size: 0.82rem;
}

.auth-divider::before,
.auth-divider::after {
  content: "";
  flex: 1;
  height: 1px;
  background: var(--border-subtle);
}

.auth-form {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.form-field {
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
}

.text-input {
  min-block-size: 2.5rem;
  padding: 0.45rem 0.75rem;
  border-radius: var(--radius-md);
  border: 1px solid var(--border-strong);
  background: var(--bg-surface);
  color: var(--text-primary);
  font-size: 0.95rem;
}

.auth-error {
  margin: 0;
  padding: 0.5rem 0.75rem;
  border-radius: 8px;
  background: var(--error-bg);
  color: var(--error-text);
  font-size: 0.86rem;
  font-weight: 600;
}

.auth-submit-row {
  display: flex;
  gap: 0.5rem;
  margin-top: 0.25rem;
}

.auth-submit-row .btn {
  flex: 1;
}

/* Mobile Form-Factor Refinements */
@media (max-width: 600px) {
  .main-shell {
    padding: 0.875rem max(0.875rem, env(safe-area-inset-right)) max(1.5rem, env(safe-area-inset-bottom)) max(0.875rem, env(safe-area-inset-left));
  }
  .card {
    padding: 1rem;
  }
  .option-label {
    padding: 0.85rem;
  }
  .question-grid {
    grid-template-columns: repeat(5, 1fr);
  }
}

/* Course Home & Student Journey */
.brand-btn {
  border: 0;
  background: transparent;
  color: inherit;
  padding: 0;
  text-align: left;
  cursor: pointer;
  border-radius: var(--radius-md);
}

.brand-btn > span:last-child {
  display: flex;
  flex-direction: column;
}

.site-title-inline {
  font-size: 1.08rem;
  font-weight: 700;
  line-height: 1.2;
}

.hero-card {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 1.25rem;
  margin-bottom: 1.5rem;
  background: linear-gradient(135deg, var(--bg-surface) 0%, var(--accent-soft) 100%);
}

.hero-eyebrow {
  margin: 0 0 0.25rem;
  font-size: 0.82rem;
  font-weight: 700;
  color: var(--accent);
  text-transform: uppercase;
  letter-spacing: 0.03em;
}

.hero-title {
  margin: 0 0 0.4rem;
  font-size: clamp(1.35rem, 2.5vw, 1.8rem);
  line-height: 1.2;
}

.hero-subtitle {
  margin: 0;
  max-width: 62ch;
  color: var(--text-secondary);
}

.hero-cta {
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  gap: 0.4rem;
}

.hero-note {
  font-size: 0.8rem;
  color: var(--text-secondary);
}

.hero-summary {
  display: flex;
  flex-wrap: wrap;
  gap: 0.65rem;
}

.chapters-toolbar {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  align-items: center;
  gap: 0.75rem;
  margin-bottom: 1rem;
}

.chapters-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 0.875rem;
}

.chapter-card {
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  gap: 0.75rem;
  padding: 1.125rem;
  border-radius: var(--radius-lg);
  border: 1.5px solid var(--border-subtle);
  background: var(--bg-surface);
  text-align: left;
}

.chapter-card.is-ready {
  border-color: var(--accent);
}

.chapter-card.is-locked {
  opacity: 0.72;
}

.chapter-card-top {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 0.5rem;
}

.chapter-num {
  font-size: 0.8rem;
  font-weight: 700;
  color: var(--text-secondary);
  text-transform: uppercase;
}

.status-pill {
  padding: 0.15rem 0.55rem;
  border-radius: 999px;
  font-size: 0.75rem;
  font-weight: 700;
}

.status-pill.is-ready {
  background: var(--success-bg);
  color: var(--success-text);
  border: 1px solid var(--success-border);
}

.status-pill.is-soon {
  background: var(--bg-subtle);
  color: var(--text-secondary);
  border: 1px solid var(--border-subtle);
}

.chapter-card-title {
  margin: 0;
  font-size: 1.05rem;
  line-height: 1.35;
}

.chapter-card-meta {
  margin: 0;
  font-size: 0.84rem;
  color: var(--text-secondary);
}

/* Chapter Workspace */
.chapter-topbar {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 0.75rem;
  margin-bottom: 0.75rem;
}

.chapter-title-wrap {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 0.65rem;
  margin-right: auto;
}

.chapter-heading {
  margin: 0;
  font-size: 1.35rem;
}

.chapter-tabs {
  margin-bottom: 1.25rem;
  border-bottom: 1px solid var(--border-subtle);
}

/* Learn Study Modules */
.learn-modules-list {
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.learn-card {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.learn-card-head {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  align-items: flex-start;
  gap: 0.75rem;
}

.learn-card-title {
  margin: 0.2rem 0 0;
  font-size: 1.12rem;
}

.learn-summary {
  margin: 0;
  color: var(--text-secondary);
}

.learn-points {
  margin: 0;
  padding-left: 1.25rem;
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
}

.learn-pearl {
  margin: 0;
  padding: 0.65rem 0.875rem;
  border-radius: var(--radius-md);
  background: var(--accent-soft);
  font-size: 0.9rem;
  font-weight: 500;
}

.learn-card-actions {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  align-items: center;
  gap: 0.5rem;
  padding-top: 0.75rem;
  border-top: 1px solid var(--border-subtle);
}

.btn-reviewed[aria-pressed="true"] {
  background: var(--success-bg);
  color: var(--success-text);
  border-color: var(--success-border);
}

/* X-Ray Labeling Labs */
.lab-toolbar {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  align-items: center;
  gap: 0.75rem;
  margin-bottom: 1rem;
}

.word-bank-card {
  margin-bottom: 1rem;
  padding: 0.875rem 1rem;
}

.word-bank-chips {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.word-chip {
  min-block-size: 2.25rem;
  padding: 0.35rem 0.75rem;
  border-radius: 999px;
  border: 1px solid var(--border-strong);
  background: var(--bg-subtle);
  color: var(--text-primary);
  font-size: 0.85rem;
  font-weight: 600;
  cursor: pointer;
}

.word-chip:hover {
  border-color: var(--accent);
  background: var(--accent-soft);
}

.lab-layout {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 1fr);
  gap: 1.25rem;
  align-items: start;
}

@media (max-width: 860px) {
  .lab-layout {
    grid-template-columns: 1fr;
  }
}

.xray-svg-container {
  width: 100%;
  border-radius: var(--radius-md);
  overflow: hidden;
}

.xray-svg {
  display: block;
  width: 100%;
  height: auto;
}

.lab-form {
  display: flex;
  flex-direction: column;
  gap: 0.875rem;
}

.lab-inputs-list {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
}

.lab-row {
  display: flex;
  flex-direction: column;
  gap: 0.3rem;
}

.lab-row-label {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 0.88rem;
  font-weight: 600;
}

.lab-letter-badge {
  display: inline-grid;
  place-items: center;
  width: 1.55rem;
  height: 1.55rem;
  border-radius: 50%;
  background: #fbbf24;
  color: #111827;
  font-weight: 800;
  font-size: 0.82rem;
  flex-shrink: 0;
}

.lab-input-status {
  font-size: 0.82rem;
  font-weight: 600;
}

.lab-input-status.is-correct {
  color: var(--success-text);
}

.lab-input-status.is-incorrect {
  color: var(--error-text);
}