/* Interactive problem pages — extends style.css palette. */

.problem-chapter {
  text-transform: uppercase;
  letter-spacing: 0.1em;
  font-size: 0.8rem;
  color: var(--accent-purple);
  margin-bottom: 0.25rem;
}

.problem-context {
  background-color: var(--surface-color);
  border-left: 3px solid var(--accent-cyan);
  padding: 1.25rem 1.5rem;
  border-radius: 6px;
  margin: 1.5rem 0;
}

.problem-prompt {
  margin: 1.5rem 0 1rem;
  color: var(--text-secondary);
  font-style: italic;
}

.problem-body p {
  line-height: 1.9;
}

select.cloze-select {
  display: inline-block;
  background-color: var(--surface-color);
  color: var(--text-primary);
  border: 1px solid rgba(255, 255, 255, 0.2);
  border-radius: 4px;
  padding: 0.2rem 0.4rem;
  font-family: var(--font-sans);
  font-size: 0.95rem;
  margin: 0 0.15rem;
  max-width: 100%;
  cursor: pointer;
  transition: border-color 0.15s, box-shadow 0.15s;
}

select.cloze-select:focus {
  outline: none;
  border-color: var(--accent-cyan);
  box-shadow: 0 0 0 2px var(--accent-cyan-glow);
}

select.cloze-select.correct {
  border-color: var(--keypoint-border);
  box-shadow: 0 0 0 1px var(--keypoint-border);
}

select.cloze-select.incorrect {
  border-color: #f87171;
  box-shadow: 0 0 0 1px #f87171;
}

.explanations-panel {
  margin-top: 2rem;
  padding: 1.25rem 1.5rem;
  background-color: var(--surface-color);
  border-radius: 8px;
  border: 1px solid rgba(255, 255, 255, 0.05);
}
.explanations-panel h3 {
  margin: 0 0 0.75rem;
  font-size: 1.05rem;
  color: var(--accent-purple);
}
.explanations-list {
  list-style: none;
  padding: 0;
  margin: 0;
}
.explanations-list li {
  display: flex;
  gap: 0.75rem;
  align-items: flex-start;
  padding: 0.6rem 0;
  border-bottom: 1px solid rgba(255, 255, 255, 0.05);
  font-size: 0.95rem;
  color: var(--text-secondary);
}
.explanations-list li:last-child { border-bottom: none; }
.explanations-list strong { color: var(--text-primary); }
.explain-mark {
  flex: 0 0 1.25rem;
  font-weight: 700;
  font-size: 1.1rem;
  line-height: 1.4;
}
.explain-correct .explain-mark { color: var(--keypoint-border); }
.explain-incorrect .explain-mark, .explain-unanswered .explain-mark { color: #f87171; }

.problem-actions {
  display: flex;
  align-items: center;
  gap: 1rem;
  margin-top: 2rem;
  padding-top: 1.25rem;
  border-top: 1px solid rgba(255, 255, 255, 0.08);
}

.btn {
  font-family: var(--font-sans);
  font-size: 0.95rem;
  font-weight: 600;
  padding: 0.55rem 1.2rem;
  border-radius: 6px;
  border: 1px solid transparent;
  cursor: pointer;
  transition: background-color 0.15s, border-color 0.15s;
}

.btn-primary {
  background-color: var(--accent-cyan);
  color: #0f172a;
}
.btn-primary:hover { background-color: #0891b2; }

.btn-ghost {
  background-color: transparent;
  color: var(--text-secondary);
  border-color: rgba(255, 255, 255, 0.15);
}
.btn-ghost:hover { color: var(--text-primary); border-color: rgba(255, 255, 255, 0.4); }

.score-readout {
  margin-left: auto;
  color: var(--text-secondary);
  font-size: 0.95rem;
}
.score-readout.all-correct { color: var(--keypoint-border); font-weight: 600; }

.problem-list {
  list-style: none;
  padding: 0;
  margin-top: 2rem;
}
.problem-list li {
  margin-bottom: 0.6rem;
}
.problem-list a {
  display: block;
  background-color: var(--surface-color);
  border: 1px solid rgba(255, 255, 255, 0.05);
  border-radius: 8px;
  padding: 1rem 1.25rem;
  text-decoration: none;
  color: var(--text-primary);
  transition: border-color 0.15s, transform 0.15s;
}
.problem-list a:hover {
  border-color: var(--accent-cyan);
  transform: translateX(2px);
}
.ch-tag {
  display: inline-block;
  background-color: var(--accent-purple);
  color: #0f172a;
  font-size: 0.75rem;
  font-weight: 700;
  padding: 0.15rem 0.55rem;
  border-radius: 4px;
  margin-right: 0.75rem;
  vertical-align: middle;
}