/* ── Buttons ── */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-2);
  min-height: 44px;
  min-width: 44px;
  padding: var(--space-2) var(--space-4);
  border: 1px solid transparent;
  border-radius: var(--radius-sm);
  font-family: var(--font-ui);
  font-size: var(--text-sm);
  font-weight: 600;
  line-height: 1.2;
  cursor: pointer;
  transition: background 0.15s, border-color 0.15s, color 0.15s;
}

.btn:focus-visible {
  outline: none;
  box-shadow: var(--ring);
}

.btn--primary {
  background: var(--color-primary);
  color: #fff;
}

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

.btn--secondary {
  background: var(--color-surface-2);
  color: var(--color-text);
  border-color: var(--color-border);
}

.btn--secondary:hover {
  border-color: var(--color-accent);
  color: var(--color-accent);
}

.btn--accent {
  background: var(--color-accent);
  color: var(--navy-900);
}

.btn--accent:hover {
  background: var(--cyan-400);
}

.btn--ghost {
  background: transparent;
  color: var(--color-text-muted);
  border-color: var(--color-border);
}

.btn--ghost:hover {
  background: var(--color-surface-2);
  color: var(--color-text);
}

.btn--icon {
  padding: var(--space-2);
}

.btn--sm {
  min-height: 36px;
  min-width: 36px;
  padding: var(--space-1) var(--space-3);
  font-size: 0.8125rem;
}

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

/* ── Search input ── */
.search-input {
  width: 100%;
  min-height: 44px;
  padding: var(--space-2) var(--space-3);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  background: var(--color-surface-2);
  color: var(--color-text);
  font-family: var(--font-ui);
  font-size: var(--text-base);
}

.search-input:focus {
  outline: none;
  border-color: var(--color-accent);
  box-shadow: var(--ring);
}

.search-input::placeholder {
  color: var(--color-text-muted);
}

/* ── Symbol palette ── */
.palette-recents {
  margin-bottom: var(--space-4);
}

.palette-recents__label,
.palette-category__label {
  margin: 0 0 var(--space-2);
  font-size: var(--text-sm);
  font-weight: 600;
  color: var(--color-text-muted);
}

.palette-grid {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2);
}

.symbol-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 44px;
  min-height: 44px;
  padding: var(--space-2) var(--space-3);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  background: var(--color-surface-2);
  color: var(--color-text);
  font-family: var(--font-ui);
  font-size: var(--text-base);
  font-weight: 500;
  cursor: pointer;
  transition: background 0.15s, border-color 0.15s, transform 0.1s;
}

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

.symbol-btn:focus-visible {
  outline: none;
  box-shadow: var(--ring);
}

.symbol-btn:active {
  transform: scale(0.96);
}

.symbol-btn sup,
.symbol-btn sub {
  font-size: 0.7em;
}

.symbol-btn--var {
  font-weight: 700;
  color: var(--color-highlight);
}

.palette-category {
  margin-bottom: var(--space-2);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  overflow: hidden;
}

.palette-category__toggle {
  display: flex;
  align-items: center;
  justify-content: space-between;
  width: 100%;
  min-height: 32px;
  padding: var(--space-2) var(--space-3);
  border: none;
  background: var(--color-surface-2);
  color: var(--color-text);
  font-family: var(--font-ui);
  font-size: 0.8125rem;
  font-weight: 600;
  cursor: pointer;
  text-align: left;
}

.palette-category__toggle:focus-visible {
  outline: none;
  box-shadow: inset var(--ring);
}

.palette-category__toggle-icon {
  transition: transform 0.2s;
  color: var(--color-text-muted);
}

.palette-category.is-collapsed .palette-category__toggle-icon {
  transform: rotate(-90deg);
}

.palette-category__body {
  padding: var(--space-2) var(--space-3);
}

.palette-category.is-collapsed .palette-category__body,
.palette-category__body[hidden] {
  display: none;
}

.palette-empty {
  padding: var(--space-4);
  text-align: center;
  color: var(--color-text-muted);
  font-size: var(--text-sm);
  font-style: italic;
}

/* ── MathLive editor ── */
math-field {
  display: block;
  width: 100%;
  max-width: 100%;
  min-height: 120px;
  padding: var(--space-5);
  font-size: 1.6rem;
  border: 2px solid var(--color-border);
  border-radius: var(--radius-lg);
  background: var(--color-surface);
  color: var(--color-text);
  box-shadow: var(--shadow-sm);
  transition: border-color 0.15s, box-shadow 0.15s;
  overflow-x: auto;
}

math-field:focus-within {
  border-color: var(--color-accent);
  box-shadow: var(--ring);
}

.editor-field-wrap {
  position: relative;
}

.editor-empty-state {
  display: none;
  position: absolute;
  inset: 0;
  align-items: center;
  justify-content: center;
  flex-direction: column;
  padding: var(--space-4);
  text-align: center;
  pointer-events: none;
  z-index: 0;
}

.editor-empty-state.is-visible {
  display: flex;
}

.editor-empty-state__title {
  margin: 0 0 var(--space-2);
  font-size: var(--text-base);
  font-weight: 600;
  color: var(--color-text-muted);
}

.editor-empty-state__text {
  margin: 0;
  font-size: var(--text-sm);
  color: var(--color-text-muted);
  max-width: 280px;
}

.editor-field-wrap math-field {
  position: relative;
  z-index: 1;
}

.editor-error {
  margin: var(--space-2) 0 0;
  padding: var(--space-2) var(--space-3);
  font-size: var(--text-sm);
  color: var(--color-danger);
  background: color-mix(in srgb, var(--color-danger) 10%, transparent);
  border-radius: var(--radius-sm);
  border: 1px solid color-mix(in srgb, var(--color-danger) 25%, transparent);
}

.editor-error[hidden] {
  display: none;
}

.editor-empty-hint {
  margin: var(--space-3) 0 0;
  font-size: var(--text-sm);
  color: var(--color-text-muted);
  text-align: center;
}

/* Hide hint when editor has content — toggled via JS optional; kept visible as tips */

/* ── LaTeX strip ── */
.latex-strip {
  margin-top: var(--space-4);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  overflow: hidden;
  background: var(--color-surface);
}

.latex-strip__header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--space-2) var(--space-4);
  background: var(--color-surface-2);
  border-bottom: 1px solid var(--color-border);
}

.latex-strip__title {
  margin: 0;
  font-size: var(--text-sm);
  font-weight: 600;
  color: var(--color-text-muted);
}

.latex-strip__code {
  display: block;
  width: 100%;
  min-height: 64px;
  padding: var(--space-3) var(--space-4);
  border: none;
  background: var(--color-surface-2);
  color: var(--color-text);
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  line-height: 1.6;
  resize: vertical;
  box-sizing: border-box;
}

.latex-strip__code:focus {
  outline: none;
}

.latex-strip.is-hidden {
  display: none;
}

/* ── Export bar ── */
.export-bar__actions {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2);
  margin-bottom: var(--space-3);
}

.export-bar__controls {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--space-4);
}

.export-bar__control {
  display: flex;
  align-items: center;
  gap: var(--space-2);
}

.export-bar__control label {
  font-size: var(--text-sm);
  font-weight: 600;
  color: var(--color-text-muted);
  white-space: nowrap;
}

.export-bar__control select {
  min-height: 36px;
  padding: var(--space-1) var(--space-3);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  background: var(--color-surface-2);
  color: var(--color-text);
  font-family: var(--font-ui);
  font-size: var(--text-sm);
  cursor: pointer;
}

.export-bar__control select:focus-visible {
  outline: none;
  box-shadow: var(--ring);
}

/* ── Empty states ── */
.empty-state {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: var(--space-6) var(--space-4);
  text-align: center;
  color: var(--color-text-muted);
}

.empty-state__icon {
  font-size: var(--text-2xl);
  margin-bottom: var(--space-3);
  opacity: 0.6;
}

.empty-state__title {
  margin: 0 0 var(--space-2);
  font-size: var(--text-base);
  font-weight: 600;
  color: var(--color-text);
}

.empty-state__text {
  margin: 0;
  font-size: var(--text-sm);
  max-width: 260px;
}

/* ── Toast ── */
.toast-container {
  position: fixed;
  bottom: var(--space-5);
  right: var(--space-5);
  z-index: 100;
  display: flex;
  flex-direction: column;
  gap: var(--space-2);
  pointer-events: none;
}

.toast {
  padding: var(--space-3) var(--space-4);
  background: var(--navy-900);
  color: #fff;
  border-radius: var(--radius-md);
  font-size: var(--text-sm);
  font-weight: 500;
  box-shadow: var(--shadow-lg);
  pointer-events: auto;
  animation: toast-in 0.25s ease;
  max-width: 360px;
}

.toast--success {
  background: var(--color-success);
}

.toast--error {
  background: var(--color-danger);
}

@keyframes toast-in {
  from {
    opacity: 0;
    transform: translateY(8px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* ── Dialog ── */
.dialog-backdrop {
  display: none;
  position: fixed;
  inset: 0;
  background: rgba(15, 32, 48, 0.5);
  z-index: 50;
  align-items: center;
  justify-content: center;
  padding: var(--space-4);
}

.dialog-backdrop.is-open {
  display: flex;
}

.dialog {
  width: min(480px, 100%);
  max-height: 85vh;
  overflow-y: auto;
  background: var(--color-surface);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-lg);
}

.dialog__header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--space-4) var(--space-5);
  border-bottom: 1px solid var(--color-border);
}

.dialog__title {
  margin: 0;
  font-size: var(--text-lg);
  font-weight: 600;
}

.dialog__body {
  padding: var(--space-4) var(--space-5);
}

.dialog__footer {
  padding: var(--space-4) var(--space-5);
  border-top: 1px solid var(--color-border);
  display: flex;
  justify-content: flex-end;
}

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

.shortcut-list li {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--space-2) 0;
  border-bottom: 1px solid var(--color-border);
  font-size: var(--text-sm);
}

.shortcut-list li:last-child {
  border-bottom: none;
}

.shortcut-key {
  font-family: var(--font-mono);
  font-size: 0.8125rem;
  padding: var(--space-1) var(--space-2);
  background: var(--color-surface-2);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  color: var(--color-text);
}

.btn--danger {
  background: var(--color-danger);
  color: #fff;
}

.btn--danger:hover {
  filter: brightness(1.08);
}

.dialog__footer--split {
  justify-content: space-between;
  gap: var(--space-3);
}

/* ── Equation set panel ── */
.set-panel {
  display: flex;
  flex-direction: column;
  gap: var(--space-3);
  min-height: 100%;
}

.set-toolbar {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2);
}

.set-editing-hint {
  margin: 0;
  padding: var(--space-2) var(--space-3);
  font-size: var(--text-sm);
  color: var(--color-accent);
  background: var(--color-accent-soft);
  border-radius: var(--radius-sm);
}

.set-list {
  display: flex;
  flex-direction: column;
  gap: var(--space-3);
  flex: 1;
}

.set-card {
  display: flex;
  gap: var(--space-2);
  padding: var(--space-3);
  background: var(--color-surface-2);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  transition: border-color 0.15s, box-shadow 0.15s;
}

.set-card--active {
  border-color: var(--color-accent);
  box-shadow: var(--ring);
}

.set-card--dragging {
  opacity: 0.5;
}

.set-card--drop-target {
  border-color: var(--color-highlight);
  border-style: dashed;
}

.set-card__drag {
  display: flex;
  align-items: center;
  color: var(--color-text-muted);
  cursor: grab;
  font-size: var(--text-lg);
  padding: var(--space-1);
  user-select: none;
}

.set-card__main {
  flex: 1;
  min-width: 0;
}

.set-card__header {
  display: flex;
  align-items: center;
  gap: var(--space-1);
  margin-bottom: var(--space-2);
}

.set-card__collapse {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 28px;
  min-height: 28px;
  padding: 0;
  border: 1px solid transparent;
  border-radius: var(--radius-sm);
  background: transparent;
  color: var(--color-text-muted);
  cursor: pointer;
  flex-shrink: 0;
}

.set-card__collapse:hover {
  background: var(--color-surface-2);
  border-color: var(--color-border);
}

.set-card__collapse:focus-visible {
  outline: none;
  box-shadow: var(--ring);
}

.set-card__collapse-icon {
  display: inline-block;
  font-size: var(--text-sm);
  line-height: 1;
  transition: transform 0.15s;
}

/* Chevron points down when expanded, right when collapsed. */
.set-card--collapsed .set-card__collapse-icon {
  transform: rotate(-90deg);
}

.set-card__number {
  font-size: var(--text-sm);
  font-weight: 700;
  color: var(--color-text-muted);
  padding: var(--space-1) var(--space-2);
  margin: calc(var(--space-1) * -1) calc(var(--space-2) * -1);
  border: 1px solid transparent;
  border-radius: var(--radius-sm);
  background: transparent;
  cursor: text;
  font-family: inherit;
  transition: background var(--transition-fast, 0.15s), border-color var(--transition-fast, 0.15s);
}

.set-card__number:hover {
  background: var(--color-surface-2);
  border-color: var(--color-border);
}

.set-card__number:focus-visible {
  outline: none;
  box-shadow: var(--ring);
}

.set-card__number--empty {
  font-weight: 600;
  opacity: 0.7;
  font-style: italic;
}

.set-card__label-editor {
  display: flex;
  flex-direction: column;
  gap: var(--space-2);
  margin-bottom: var(--space-2);
}

.set-card__label-editor[hidden] {
  display: none;
}

.set-card__label-input {
  width: 100%;
  min-height: 36px;
  padding: var(--space-1) var(--space-3);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  background: var(--color-surface-2);
  color: var(--color-text);
  font-family: var(--font-ui);
  font-size: var(--text-sm);
}

.set-card__label-input:focus-visible {
  outline: none;
  box-shadow: var(--ring);
}

.set-card__label-editor-actions {
  display: flex;
  gap: var(--space-2);
}

.set-card__actions {
  display: flex;
  gap: var(--space-1);
  margin-left: auto;
}

.set-card__btn {
  min-width: 44px;
  min-height: 36px;
  padding: var(--space-1) var(--space-2);
  font-size: 0.8125rem;
}

.set-card__btn--danger {
  color: var(--color-danger);
}

.set-card__btn--danger:hover {
  background: color-mix(in srgb, var(--color-danger) 12%, transparent);
}

.set-card__preview {
  display: block;
  width: 100%;
  padding: var(--space-2);
  border: 1px dashed var(--color-border);
  border-radius: var(--radius-sm);
  background: var(--color-surface);
  cursor: pointer;
  text-align: center;
  transition: border-color 0.15s;
}

.set-card__preview:hover {
  border-color: var(--color-accent);
}

.set-card__preview:focus-visible {
  outline: none;
  box-shadow: var(--ring);
}

.set-card__katex {
  display: block;
  overflow-x: auto;
  font-size: 0.95rem;
}

/* ── Collapsed cards: show only label + a compact single-line preview ── */
.set-card--collapsed .set-card__header {
  margin-bottom: 0;
}

.set-card--collapsed .set-card__actions,
.set-card--collapsed .set-card__answer,
.set-card--collapsed .set-card__label-editor {
  display: none;
}

.set-card--collapsed .set-card__preview {
  flex: 1;
  min-width: 0;
  padding: var(--space-1) var(--space-2);
  border-style: solid;
  text-align: left;
  background: transparent;
}

.set-card--collapsed .set-card__main {
  display: flex;
  align-items: center;
  gap: var(--space-2);
}

/* Keep the header (chevron + label) from shrinking, let the preview flex. */
.set-card--collapsed .set-card__header {
  flex-shrink: 0;
}

.set-card--collapsed .set-card__number {
  margin: 0;
}

.set-card--collapsed .set-card__katex {
  overflow: hidden;
  white-space: nowrap;
  text-overflow: ellipsis;
  font-size: 0.8rem;
  max-width: 100%;
  /* Fade the right edge instead of a hard cut for long equations. */
  -webkit-mask-image: linear-gradient(to right, #000 85%, transparent 100%);
  mask-image: linear-gradient(to right, #000 85%, transparent 100%);
}

.set-card--collapsed .set-card__katex .katex-display {
  margin: 0;
  text-align: left;
}

.set-card__answer {
  margin-top: var(--space-2);
  padding-top: var(--space-2);
  border-top: 1px solid var(--color-border);
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--space-2);
}

.set-card__answer-label {
  font-size: var(--text-sm);
  font-weight: 600;
  color: var(--color-text-muted);
}

.set-card__answer-preview {
  width: 100%;
  padding: var(--space-2);
  background: var(--color-surface);
  border-radius: var(--radius-sm);
}

.set-card__answer-field-mount {
  width: 100%;
}

.set-card__answer-field {
  display: block;
  width: 100%;
  min-height: 3rem;
  padding: var(--space-2) var(--space-3);
  font-size: 1.1rem;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  background: var(--color-surface);
  color: var(--color-text);
  box-sizing: border-box;
}

.set-card__answer-field:focus-within {
  border-color: var(--color-accent);
  box-shadow: var(--ring);
}

.set-card__answer-field::part(virtual-keyboard-toggle) {
  display: none;
}

.set-card__answer-error {
  margin: 0;
  padding: var(--space-2) var(--space-3);
  font-size: var(--text-sm);
  color: var(--color-danger);
  background: color-mix(in srgb, var(--color-danger) 10%, transparent);
  border-radius: var(--radius-sm);
  border: 1px solid color-mix(in srgb, var(--color-danger) 25%, transparent);
}

.set-card__answer-error[hidden] {
  display: none;
}

.set-card__answer-editor {
  width: 100%;
  display: flex;
  flex-direction: column;
  gap: var(--space-2);
}

.set-card__answer-editor[hidden] {
  display: none;
}

.set-card__answer-editor-actions {
  display: flex;
  gap: var(--space-2);
}

.set-batch {
  margin-top: auto;
  padding-top: var(--space-4);
  border-top: 1px solid var(--color-border);
}

.set-batch__title {
  margin: 0 0 var(--space-3);
  font-size: var(--text-sm);
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  color: var(--color-text-muted);
}

.set-batch__actions {
  display: flex;
  flex-direction: column;
  gap: var(--space-2);
  margin-bottom: var(--space-3);
}

.set-batch__actions .btn {
  width: 100%;
  justify-content: center;
}

.set-batch__io {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2);
}

.empty-state--compact {
  padding: var(--space-5) var(--space-3);
}

.empty-state--compact .empty-state__icon {
  font-size: var(--text-xl);
}

/* ── Format toolbar ── */
.format-toolbar {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--space-3);
  min-width: 0;
  margin-top: var(--space-4);
  padding: var(--space-3) var(--space-4);
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
}

.format-toolbar__label {
  font-size: var(--text-sm);
  font-weight: 600;
  color: var(--color-text-muted);
}

.format-toolbar__colors {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2);
}

.format-color-btn {
  width: 44px;
  height: 44px;
  border: 2px solid var(--color-border);
  border-radius: var(--radius-sm);
  background: var(--swatch);
  cursor: pointer;
  transition: transform 0.1s, box-shadow 0.15s;
}

.format-color-btn:hover {
  transform: scale(1.08);
}

.format-color-btn:focus-visible {
  outline: none;
  box-shadow: var(--ring);
}

/* ── Export LaTeX target dropdown ── */
.export-bar__latex-group {
  display: inline-flex;
  align-items: stretch;
}

.export-bar__target-select {
  min-height: 44px;
  max-width: 160px;
  padding: var(--space-1) var(--space-2);
  border: 1px solid var(--color-border);
  border-left: none;
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  background: var(--color-surface-2);
  color: var(--color-text);
  font-family: var(--font-ui);
  font-size: var(--text-sm);
  cursor: pointer;
}

.export-bar__latex-group .btn {
  border-radius: var(--radius-sm) 0 0 var(--radius-sm);
}

/* ── Collapsible palette sections (Categories, Templates) ── */
.palette-section {
  margin: 0;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  overflow: hidden;
  flex-shrink: 0;
}

.palette-section__header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-2);
  padding: var(--space-1) var(--space-2);
  background: var(--color-surface-2);
}

.palette-section__toggle {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex: 1;
  gap: var(--space-2);
  min-height: 32px;
  padding: var(--space-1) var(--space-2);
  border: none;
  background: transparent;
  color: var(--color-text);
  font-family: var(--font-ui);
  font-size: 0.8125rem;
  font-weight: 600;
  cursor: pointer;
  text-align: left;
}

.palette-section__toggle:focus-visible {
  outline: none;
  box-shadow: inset var(--ring);
}

.palette-section__title {
  flex: 1;
}

.palette-section__chevron {
  transition: transform 0.2s;
  color: var(--color-text-muted);
}

.palette-section.is-collapsed .palette-section__chevron {
  transform: rotate(-90deg);
}

.palette-section__body {
  padding: var(--space-2);
}

.palette-section__body[hidden] {
  display: none !important;
}

.palette-category--templates {
  margin-bottom: var(--space-2);
}

.palette-category--templates:last-child {
  margin-bottom: 0;
}

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

.template-list__item {
  display: flex;
  align-items: center;
  gap: var(--space-1);
}

.template-list__apply {
  flex: 1;
  min-height: 32px;
  padding: var(--space-1) var(--space-2);
  border: none;
  border-radius: var(--radius-sm);
  background: transparent;
  color: var(--color-text);
  font-family: var(--font-ui);
  font-size: 0.8125rem;
  text-align: left;
  cursor: pointer;
}

.template-list__apply:hover {
  background: var(--color-accent-soft);
  color: var(--color-accent);
}

.template-list__apply:focus-visible {
  outline: none;
  box-shadow: var(--ring);
}

.template-list__delete {
  min-width: 36px;
  min-height: 36px;
}

/* ── Board mode ── */
.board-mode {
  position: fixed;
  inset: 0;
  z-index: 200;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  background: #0a1520;
  color: #fff;
  padding: var(--space-6);
}

.board-mode[hidden] {
  display: none;
}

body.board-mode-active {
  overflow: hidden;
}

.board-mode__content {
  max-width: 95vw;
  max-height: 80vh;
  overflow: auto;
  font-size: clamp(2rem, 6vw, 5rem);
}

.board-mode__content .katex {
  color: #fff;
}

.board-mode__hint {
  position: absolute;
  bottom: var(--space-5);
  font-size: var(--text-sm);
  color: rgba(255, 255, 255, 0.5);
}

.board-mode__exit {
  position: absolute;
  top: var(--space-4);
  right: var(--space-4);
  min-height: 44px;
}

/* ── Onboarding ── */
.onboarding {
  position: fixed;
  inset: 0;
  z-index: 250;
}

.onboarding[hidden] {
  display: none;
}

body.onboarding-active {
  overflow: hidden;
}

.onboarding__backdrop {
  position: absolute;
  inset: 0;
  background: rgba(15, 32, 48, 0.55);
}

.onboarding__spotlight {
  position: fixed;
  border-radius: var(--radius-md);
  box-shadow: 0 0 0 9999px rgba(15, 32, 48, 0.55);
  pointer-events: none;
  z-index: 1;
  transition: top 0.2s ease, left 0.2s ease, width 0.2s ease, height 0.2s ease;
}

.onboarding__spotlight[hidden] {
  display: none;
}

.onboarding__card {
  position: fixed;
  z-index: 2;
  width: min(360px, calc(100vw - 32px));
  padding: var(--space-4);
  background: var(--color-surface);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-lg);
}

.onboarding__progress {
  margin: 0 0 var(--space-2);
  font-size: var(--text-sm);
  font-weight: 600;
  color: var(--color-accent);
}

.onboarding__title {
  margin: 0 0 var(--space-2);
  font-size: var(--text-lg);
}

.onboarding__body {
  margin: 0 0 var(--space-4);
  font-size: var(--text-sm);
  color: var(--color-text-muted);
  line-height: 1.6;
}

.onboarding__actions {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-3);
}

.onboarding__nav {
  display: flex;
  gap: var(--space-2);
}

@media (prefers-reduced-motion: reduce) {
  .onboarding__spotlight {
    transition: none;
  }

  .toast {
    animation: none;
  }
}

.dialog {
  outline: none;
}

/* ── Phase badge ── */
.phase-badge {
  display: inline-block;
  padding: 2px var(--space-2);
  font-size: 0.6875rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  background: var(--color-accent-soft);
  color: var(--color-accent);
  border-radius: var(--radius-sm);
}

.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;
}

@media (max-width: 767px) {
  .set-card__header {
    flex-wrap: wrap;
    gap: var(--space-2);
  }

  .set-card__actions {
    margin-left: 0;
    width: 100%;
    justify-content: flex-end;
  }
}