:root {
  --dd-accent: #0b57d0;
  --dd-accent-soft: rgba(11, 87, 208, 0.14);
  --dd-surface: #f7fbff;
  --dd-surface-strong: #eef5ff;
  --dd-border: #d6e1ef;
  --dd-text: #122033;
  --dd-muted: #526173;
  --dd-guide: #9db4d0;
  --dd-current: #0b57d0;
  --dd-subtract: #0c7a5b;
  --dd-remainder: #7a4a00;
  --dd-target: rgba(255, 215, 106, 0.28);
}

:root.dark {
  --dd-surface: #0f1722;
  --dd-surface-strong: #152234;
  --dd-border: #233247;
  --dd-text: #e5eef8;
  --dd-muted: #b8c5d4;
  --dd-guide: #5c708c;
  --dd-target: rgba(255, 215, 106, 0.18);
}

.decimal-division .eyebrow {
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--dd-accent);
  font-weight: 800;
  margin-bottom: 6px;
}

.decimal-division .dd-grid {
  display: grid;
  gap: 16px;
}

.decimal-division .dd-grid.two-col {
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  align-items: start;
}

.decimal-division .dd-field-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 12px;
}

.decimal-division .dd-field,
.decimal-division .dd-options,
.decimal-division .dd-panel {
  background: var(--dd-surface);
  border: 1px solid var(--dd-border);
  border-radius: 14px;
  padding: 12px;
}

.decimal-division .dd-field .label,
.decimal-division .dd-options .label {
  display: block;
  font-weight: 700;
  color: var(--dd-text);
  margin-bottom: 6px;
}

.decimal-division .dd-options .checkbox {
  display: flex;
  gap: 8px;
  align-items: flex-start;
  margin-top: 8px;
  color: var(--dd-text);
}

.decimal-division .dd-actions,
.decimal-division .chip-row,
.decimal-division .step-controls {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.decimal-division .dd-actions .button {
  min-width: 120px;
}

.decimal-division .chip {
  border: 1px solid var(--dd-border);
  background: var(--dd-surface-strong);
  color: var(--dd-text);
  padding: 8px 12px;
  border-radius: 999px;
  font-weight: 700;
  cursor: pointer;
}

.decimal-division .chip:hover,
.decimal-division .chip:focus-visible {
  border-color: var(--dd-accent);
  outline: none;
}

.decimal-division .result-panel {
  background: linear-gradient(180deg, rgba(11, 87, 208, 0.08) 0%, rgba(11, 87, 208, 0.02) 100%);
  border: 1px solid var(--dd-border);
  border-radius: 16px;
  padding: 16px;
  box-shadow: 0 16px 40px rgba(11, 87, 208, 0.12);
}

.decimal-division .result-value {
  font-size: clamp(2rem, 5vw, 3rem);
  font-weight: 900;
  color: var(--dd-text);
  line-height: 1.1;
  word-break: break-word;
}

.decimal-division #result-note {
  margin-top: 10px;
  display: grid;
  gap: 6px;
}

.decimal-division .result-line {
  color: var(--dd-muted);
}

.decimal-division .check-panel {
  margin-top: 12px;
  display: grid;
  gap: 10px;
  padding: 12px;
  background: rgba(255, 255, 255, 0.7);
  border: 1px solid var(--dd-border);
  border-radius: 14px;
}

.decimal-division .check-panel__title,
.decimal-division .check-card__title {
  font-weight: 800;
  color: var(--dd-text);
}

.decimal-division .check-panel__cards {
  display: grid;
  gap: 10px;
}

.decimal-division .check-card {
  display: grid;
  gap: 6px;
  padding: 10px;
  background: var(--dd-surface);
  border: 1px solid var(--dd-border);
  border-radius: 12px;
}

.decimal-division .check-card--approx {
  background: var(--dd-surface-strong);
}

.decimal-division .check-card__expression {
  font-weight: 700;
  color: var(--dd-text);
  word-break: break-word;
}

.decimal-division .check-card__note {
  color: var(--dd-muted);
}

.decimal-division .layout-shell {
  background: #fff;
  border: 1px solid var(--dd-border);
  border-radius: 14px;
  padding: 12px;
  overflow-x: auto;
}

.decimal-division .steps-list {
  margin: 0;
  padding-inline-start: 20px;
  display: grid;
  gap: 8px;
}

.decimal-division .steps-list li {
  background: var(--dd-surface);
  border: 1px solid var(--dd-border);
  border-radius: 10px;
  padding: 8px 10px;
  line-height: 1.6;
}

.decimal-division .steps-list li.active-step {
  background: var(--dd-accent-soft);
  border-color: var(--dd-accent);
  font-weight: 700;
}

.decimal-division .input-hint.error {
  color: #b3261e;
}

.decimal-division .dd-transform {
  display: grid;
  gap: 12px;
}

.decimal-division .dd-transform-card {
  background: var(--dd-surface);
  border: 1px solid var(--dd-border);
  border-radius: 14px;
  padding: 12px;
  display: grid;
  gap: 10px;
}

.decimal-division .dd-transform-card.is-active {
  background: var(--dd-accent-soft);
  border-color: var(--dd-accent);
  outline: 2px solid rgba(11, 87, 208, 0.25);
  outline-offset: 1px;
}

.decimal-division .dd-transform-grid {
  display: grid;
  gap: 8px;
}

.decimal-division .dd-transform-line {
  display: grid;
  gap: 8px;
  grid-template-columns: minmax(90px, 130px) 1fr;
  align-items: start;
}

.decimal-division .dd-transform-label {
  color: var(--dd-muted);
  font-weight: 700;
}

.decimal-division .dd-transform-equation {
  font-weight: 700;
  color: var(--dd-text);
}

.decimal-division .dd-school {
  display: grid;
  gap: 2px;
  min-width: max-content;
  direction: ltr;
  unicode-bidi: isolate;
  --dd-cell-size: 1.85rem;
  --dd-cell-gap: 2px;
  --dd-school-font-size: 1.05rem;
  --dd-rule-width: 2px;
  font-family: var(--font-mono, 'Roboto Mono', 'Fira Code', monospace);
  font-size: var(--dd-school-font-size);
  line-height: 1;
  font-variant-numeric: tabular-nums;
}

.decimal-division .dd-school-row {
  display: grid;
  grid-template-columns: calc(var(--school-left-cols, 3) * var(--dd-cell-size) + 0.6rem) auto;
  align-items: center;
  gap: 0;
}

.decimal-division .dd-school-row.is-active {
  background: var(--dd-accent-soft);
  border-radius: 6px;
  outline: 2px solid rgba(11, 87, 208, 0.25);
  outline-offset: 1px;
}

.decimal-division .dd-school-left {
  min-width: calc(var(--school-left-cols, 3) * var(--dd-cell-size));
  padding-right: 0.5rem;
  min-height: var(--dd-cell-size);
  display: flex;
  justify-content: flex-end;
  align-items: center;
}

.decimal-division .dd-school-left--bracket {
  border-right: var(--dd-rule-width) solid #1b1f24;
}

.decimal-division .dd-school-row--dividend .dd-school-right {
  border-top: var(--dd-rule-width) solid #1b1f24;
}

.decimal-division .dd-divisor {
  font-weight: 800;
  color: var(--dd-text);
  font-family: inherit;
  font-variant-numeric: inherit;
}

.decimal-division .dd-school-right {
  min-height: var(--dd-cell-size);
  padding-left: 0.5rem;
  display: grid;
  grid-template-columns: repeat(var(--school-digit-cols, 2), minmax(var(--dd-cell-size), var(--dd-cell-size)));
  gap: var(--dd-cell-gap);
  align-items: center;
  position: relative;
}

.decimal-division .dd-token {
  display: flex;
  justify-content: center;
  align-items: center;
  min-height: var(--dd-cell-size);
  min-width: var(--dd-cell-size);
  white-space: pre;
  text-align: center;
}

.decimal-division .dd-token--empty {
  opacity: 0;
}

.decimal-division .dd-token--quotient {
  font-weight: 800;
  color: var(--dd-current);
}

.decimal-division .dd-token--ghost {
  color: var(--dd-guide);
  opacity: 0.72;
  outline: 1px dashed var(--dd-guide);
  outline-offset: -4px;
  text-decoration: none;
}

.decimal-division .dd-token--dividend {
  color: var(--dd-text);
}

.decimal-division .dd-token--subtract {
  color: var(--dd-subtract);
  font-weight: 700;
}

.decimal-division .dd-token--remainder {
  color: var(--dd-remainder);
  font-weight: 700;
}

.decimal-division .dd-token--current {
  color: var(--dd-current);
  font-weight: 800;
}

.decimal-division .dd-token--bring {
  color: #c17900;
  font-weight: 800;
}

.decimal-division .dd-token--brought {
  color: #c17900;
  font-weight: 800;
}

.decimal-division .dd-token--appended {
  color: #8c5d00;
  font-weight: 700;
}

.decimal-division .dd-rule-line {
  border-bottom: var(--dd-rule-width) solid #1b1f24;
  transform: translateY(-1px);
}

.decimal-division .dd-overlay-token {
  position: absolute;
  line-height: 1;
  pointer-events: none;
}

.decimal-division .dd-overlay-token--shape {
  display: block;
}

.decimal-division .dd-overlay-token--decimal {
  top: 50%;
  left: calc(
    var(--school-overlay-after-col, 0) * var(--dd-cell-size) +
    var(--school-overlay-after-col, 0) * var(--dd-cell-gap) - 0.18rem
  );
  transform: translateY(-50%);
  font-weight: 800;
  color: var(--dd-guide);
}

.decimal-division .dd-overlay-token--bring {
  top: calc(var(--dd-cell-size) * -0.06);
  left: calc(
    var(--school-overlay-after-col, 1) * var(--dd-cell-size) +
    (var(--school-overlay-after-col, 1) - 1) * var(--dd-cell-gap) -
    0.01rem
  );
  color: #c17900;
  font-weight: 800;
  width: 0.5rem;
  height: 0.72rem;
}

.decimal-division .dd-overlay-token--bring::before {
  content: '';
  position: absolute;
  left: 50%;
  top: 0.02rem;
  width: 2px;
  height: 0.38rem;
  background: currentColor;
  transform: translateX(-50%);
  border-radius: 999px;
}

.decimal-division .dd-overlay-token--bring::after {
  content: '';
  position: absolute;
  left: 50%;
  top: 0.3rem;
  width: 0.32rem;
  height: 0.32rem;
  border-right: 2px solid currentColor;
  border-bottom: 2px solid currentColor;
  transform: translateX(-50%) rotate(45deg);
  box-sizing: border-box;
}

.decimal-division .dd-overlay-token--append {
  top: calc(var(--dd-cell-size) * -0.02);
  left: calc(
    var(--school-overlay-after-col, 1) * var(--dd-cell-size) +
    (var(--school-overlay-after-col, 1) - 1) * var(--dd-cell-gap) -
    0.01rem
  );
  color: #8c5d00;
  font-weight: 800;
  font-size: 0.62rem;
  letter-spacing: 0.01em;
  line-height: 1;
}

.decimal-division .dd-overlay-token--append::before {
  content: '+0';
}

.decimal-division .dd-token.is-active {
  background: var(--dd-target);
  outline: 2px solid rgba(11, 87, 208, 0.28);
  outline-offset: -2px;
  text-decoration: underline;
  text-underline-offset: 0.1em;
}

.decimal-division .dd-token--ghost.is-active {
  color: var(--dd-current);
  opacity: 1;
  outline-style: solid;
}

.decimal-division.is-teacher .dd-school,
.decimal-division.teacher-mode .dd-school {
  --dd-cell-size: 2.15rem;
  --dd-school-font-size: 1.12rem;
  --dd-rule-width: 3px;
}

.decimal-division.is-teacher .dd-divisor,
.decimal-division.teacher-mode .dd-divisor,
.decimal-division .dd-transform.is-teacher,
.decimal-division.teacher-mode .dd-transform {
  font-size: 1.12rem;
}

@media (max-width: 640px) {
  .decimal-division .dd-transform-line {
    grid-template-columns: 1fr;
  }

  .decimal-division .result-panel {
    padding: 14px;
  }
}