.substitution-drill-item {
  margin-bottom: 2rem;
  padding-bottom: 1.5rem;
  border-bottom: 1px solid #e0e0e0;
}

.substitution-drill-item:last-child {
  border-bottom: none;
}

.substitution-drill-template {
  font-weight: 600;
  margin-bottom: 0.75rem;
}

.substitution-drill-number {
  margin-right: 0.4rem;
  color: #555;
}

.substitution-drill-table {
  width: 100%;
  border-collapse: collapse;
}

.substitution-drill-table tr {
  vertical-align: top;
}

.substitution-drill-table td {
  padding: 0.2rem 0.5rem 0.2rem 0;
}

.sub-label {
  width: 1.75rem;
  font-weight: 600;
  color: #555;
  white-space: nowrap;
  flex-shrink: 0;
}

.sub-hints {
  width: 45%;
}

.sub-answers {
  width: 55%;
  color: #333;
  filter: blur(4px);
  user-select: none;
  transition: filter 0.15s ease;
}

.substitution-drill-item:hover .sub-answers {
  filter: none;
  user-select: auto;
}

.sub-hint-btn {
  background: none;
  border: none;
  padding: 0;
  margin: 0;
  font: inherit;
  color: inherit;
  cursor: pointer;
  text-decoration: underline;
  text-decoration-style: dotted;
  text-underline-offset: 2px;
}

.sub-hint-btn:hover {
  color: #1976d2;
  text-decoration-style: solid;
}

.sub-hint-btn.active {
  color: #1976d2;
  font-weight: 600;
  text-decoration-style: solid;
}

.sub-sep {
  color: #999;
}

.sub-ans-sep {
  color: #999;
}

.sub-answer {
  /* primary answer — default text */
}

.sub-answer-alt {
  color: #888;
  font-style: italic;
  font-size: 0.92em;
}

.sub-alt-sep {
  color: #ccc;
  font-size: 0.85em;
  margin: 0 1px;
}

.sub-answer-group {
  border-radius: 3px;
  transition: background 0.15s ease;
}

.sub-answer-group.highlighted {
  background: #e3f2fd;
  outline: 3px solid #e3f2fd;
}