/* ============================================
   Exam Practice Component for mdBook
   MCQ + Open Questions
   ============================================ */

/* ---- Shared Variables ---- */
.exam-set {
  --exam-accent: #6366f1;
  --exam-accent-light: #818cf8;
  --exam-accent-dark: #4f46e5;
  --exam-correct: #22c55e;
  --exam-wrong: #ef4444;
  --exam-radius: 10px;
}

/* ============================================
   Exam Set Container
   ============================================ */

.exam-set {
  border: 1.5px solid color-mix(in srgb, var(--exam-accent) 18%, transparent);
  border-radius: 14px;
  padding: 24px;
  margin: 32px 0;
  background: color-mix(in srgb, var(--exam-accent) 2%, var(--bg));
}

.exam-set-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 12px;
  margin-bottom: 20px;
  padding-bottom: 16px;
  border-bottom: 1px solid color-mix(in srgb, var(--exam-accent) 12%, transparent);
}

.exam-set-title {
  font-size: 17px;
  font-weight: 700;
  color: var(--fg);
  display: flex;
  align-items: center;
  gap: 10px;
}

.exam-set-title .exam-set-icon {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 32px;
  height: 32px;
  border-radius: 8px;
  background: linear-gradient(135deg, var(--exam-accent), var(--exam-accent-dark));
  color: #fff;
  font-size: 15px;
  flex-shrink: 0;
}

.exam-set-stats {
  display: flex;
  align-items: center;
  gap: 14px;
  font-size: 13px;
  font-weight: 600;
}

.exam-score {
  color: var(--exam-accent);
}

.exam-set-bar {
  width: 90px;
  height: 5px;
  background: color-mix(in srgb, var(--exam-accent) 15%, var(--bg));
  border-radius: 3px;
  overflow: hidden;
}

.exam-set-bar-fill {
  height: 100%;
  width: 0%;
  background: linear-gradient(90deg, var(--exam-accent), var(--exam-accent-light));
  border-radius: 3px;
  transition: width 0.4s ease;
}

.exam-set-controls {
  display: flex;
  gap: 10px;
  margin-top: 20px;
  padding-top: 16px;
  border-top: 1px solid color-mix(in srgb, var(--exam-accent) 12%, transparent);
  flex-wrap: wrap;
}

.exam-btn {
  padding: 8px 16px;
  border-radius: 7px;
  font-size: 13px;
  font-weight: 600;
  cursor: pointer;
  border: none;
  transition: all 0.2s ease;
}

.exam-btn-check {
  background: var(--exam-accent);
  color: #fff;
}

.exam-btn-check:hover {
  background: var(--exam-accent-dark);
}

.exam-btn-reset {
  background: color-mix(in srgb, var(--exam-accent) 12%, var(--bg));
  color: var(--exam-accent);
  border: 1px solid color-mix(in srgb, var(--exam-accent) 25%, transparent);
}

.exam-btn-reset:hover {
  background: color-mix(in srgb, var(--exam-accent) 20%, var(--bg));
}

.exam-btn-shuffle {
  background: color-mix(in srgb, var(--exam-accent) 12%, var(--bg));
  color: var(--exam-accent);
  border: 1px solid color-mix(in srgb, var(--exam-accent) 25%, transparent);
}

.exam-btn-shuffle:hover {
  background: color-mix(in srgb, var(--exam-accent) 20%, var(--bg));
}

/* ============================================
   MCQ Card
   ============================================ */

.mcq-card {
  position: relative;
  border-radius: var(--exam-radius);
  margin: 18px 0;
  background: var(--bg);
  border: 1px solid color-mix(in srgb, var(--exam-accent) 14%, transparent);
  overflow: hidden;
  transition: box-shadow 0.2s ease;
}

.mcq-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 3px;
  height: 100%;
  background: var(--exam-accent);
  opacity: 0.5;
  transition: opacity 0.2s ease;
}

.mcq-card:hover::before {
  opacity: 1;
}

.mcq-card.answered-correct::before {
  background: var(--exam-correct);
  opacity: 1;
}

.mcq-card.answered-wrong::before {
  background: var(--exam-wrong);
  opacity: 1;
}

/* Question number + meta row */
.mcq-head {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 14px 18px 0;
}

.mcq-num {
  font-size: 12px;
  font-weight: 700;
  color: var(--exam-accent);
  text-transform: uppercase;
  letter-spacing: 0.4px;
}

.mcq-tag {
  margin-left: auto;
  padding: 2px 9px;
  border-radius: 12px;
  font-size: 10px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.3px;
}

.mcq-tag-easy {
  background: color-mix(in srgb, #22c55e 12%, var(--bg));
  color: #22c55e;
  border: 1px solid color-mix(in srgb, #22c55e 25%, transparent);
}

.mcq-tag-medium {
  background: color-mix(in srgb, #f59e0b 12%, var(--bg));
  color: #f59e0b;
  border: 1px solid color-mix(in srgb, #f59e0b 25%, transparent);
}

.mcq-tag-hard {
  background: color-mix(in srgb, #ef4444 12%, var(--bg));
  color: #ef4444;
  border: 1px solid color-mix(in srgb, #ef4444 25%, transparent);
}

.mcq-tag-tricky {
  background: color-mix(in srgb, #a855f7 12%, var(--bg));
  color: #a855f7;
  border: 1px solid color-mix(in srgb, #a855f7 25%, transparent);
}

/* Question text */
.mcq-body {
  padding: 12px 18px 16px;
}

.mcq-question {
  font-size: 20px;
  line-height: 1.65;
  color: var(--fg);
  margin-bottom: 14px;
}

.mcq-question strong {
  color: var(--exam-accent);
}

/* Options */
.mcq-options {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.mcq-option {
  display: flex;
  align-items: flex-start;
  gap: 10px;
  padding: 10px 14px;
  border-radius: 8px;
  border: 1.5px solid color-mix(in srgb, var(--fg) 10%, transparent);
  background: var(--bg);
  cursor: pointer;
  transition: all 0.15s ease;
  font-size: 17px;
  line-height: 1.55;
  color: var(--fg);
  user-select: none;
}

.mcq-option:hover {
  border-color: color-mix(in srgb, var(--exam-accent) 40%, transparent);
  background: color-mix(in srgb, var(--exam-accent) 5%, var(--bg));
}

.mcq-option.selected {
  border-color: var(--exam-accent);
  background: color-mix(in srgb, var(--exam-accent) 8%, var(--bg));
}

.mcq-option-letter {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 24px;
  height: 24px;
  border-radius: 6px;
  font-size: 12px;
  font-weight: 700;
  flex-shrink: 0;
  background: color-mix(in srgb, var(--fg) 8%, var(--bg));
  color: var(--fg);
  transition: all 0.15s ease;
}

.mcq-option.selected .mcq-option-letter {
  background: var(--exam-accent);
  color: #fff;
}

.mcq-option-text {
  padding-top: 2px;
}

/* Checked states */
.mcq-card.checked .mcq-option {
  cursor: default;
  pointer-events: none;
}

.mcq-card.checked .mcq-option.correct {
  border-color: var(--exam-correct);
  background: color-mix(in srgb, var(--exam-correct) 8%, var(--bg));
}

.mcq-card.checked .mcq-option.correct .mcq-option-letter {
  background: var(--exam-correct);
  color: #fff;
}

.mcq-card.checked .mcq-option.selected.wrong {
  border-color: var(--exam-wrong);
  background: color-mix(in srgb, var(--exam-wrong) 6%, var(--bg));
  text-decoration: line-through;
  opacity: 0.7;
}

.mcq-card.checked .mcq-option.selected.wrong .mcq-option-letter {
  background: var(--exam-wrong);
  color: #fff;
}

/* Explanation (revealed after check) */
.mcq-explanation {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.35s ease;
  border-top: 1px solid transparent;
}

.mcq-card.checked .mcq-explanation {
  max-height: 800px;
  border-top: 1px solid color-mix(in srgb, var(--exam-correct) 15%, transparent);
}

.mcq-explanation-inner {
  padding: 0 18px;
  opacity: 0;
  max-height: 0;
  overflow: hidden;
  transition: all 0.3s ease 0.1s;
}

.mcq-card.checked .mcq-explanation-inner {
  padding: 14px 18px;
  opacity: 1;
  max-height: 800px;
}

.mcq-explanation-label {
  font-size: 11px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.4px;
  color: var(--exam-correct);
  margin-bottom: 6px;
}

.mcq-explanation-text {
  font-size: 17px;
  line-height: 1.7;
  color: var(--fg);
  opacity: 0.9;
}

.mcq-explanation-text code {
  background: var(--inline-code-bg);
  padding: 1px 5px;
  border-radius: 4px;
  font-size: 0.9em;
}

/* Per-card check button */
.mcq-check-btn {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  width: 100%;
  padding: 10px;
  margin-top: 12px;
  background: color-mix(in srgb, var(--exam-accent) 8%, var(--bg));
  border: 1px dashed color-mix(in srgb, var(--exam-accent) 25%, transparent);
  border-radius: 7px;
  color: var(--exam-accent);
  font-size: 13px;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.15s ease;
}

.mcq-check-btn:hover {
  background: color-mix(in srgb, var(--exam-accent) 14%, var(--bg));
  border-style: solid;
}

.mcq-card.checked .mcq-check-btn {
  display: none;
}

/* ============================================
   Open / Written Question Card
   ============================================ */

.open-card {
  position: relative;
  border-radius: var(--exam-radius);
  margin: 18px 0;
  background: var(--bg);
  border: 1px solid color-mix(in srgb, #14b8a6 14%, transparent);
  overflow: hidden;
  transition: box-shadow 0.2s ease;
}

.open-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 3px;
  height: 100%;
  background: #14b8a6;
  opacity: 0.5;
}

.open-head {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 14px 18px 0;
}

.open-num {
  font-size: 12px;
  font-weight: 700;
  color: #14b8a6;
  text-transform: uppercase;
  letter-spacing: 0.4px;
}

.open-type {
  margin-left: auto;
  padding: 2px 9px;
  border-radius: 12px;
  font-size: 10px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.3px;
  background: color-mix(in srgb, #14b8a6 12%, var(--bg));
  color: #14b8a6;
  border: 1px solid color-mix(in srgb, #14b8a6 25%, transparent);
}

.open-type-calc {
  background: color-mix(in srgb, #f59e0b 12%, var(--bg));
  color: #f59e0b;
  border: 1px solid color-mix(in srgb, #f59e0b 25%, transparent);
}

.open-type-tricky {
  background: color-mix(in srgb, #a855f7 12%, var(--bg));
  color: #a855f7;
  border: 1px solid color-mix(in srgb, #a855f7 25%, transparent);
}

.open-body {
  padding: 12px 18px 16px;
}

.open-question {
  font-size: 15px;
  line-height: 1.65;
  color: var(--fg);
}

.open-question strong {
  color: #14b8a6;
}

/* Scratch area (optional textarea for practice) */
.open-scratch {
  width: 100%;
  min-height: 80px;
  margin-top: 12px;
  padding: 10px 12px;
  border-radius: 7px;
  border: 1.5px solid color-mix(in srgb, var(--fg) 10%, transparent);
  background: color-mix(in srgb, var(--fg) 3%, var(--bg));
  color: var(--fg);
  font-family: inherit;
  font-size: 14px;
  line-height: 1.6;
  resize: vertical;
  transition: border-color 0.2s ease;
}

.open-scratch:focus {
  outline: none;
  border-color: #14b8a6;
}

.open-scratch::placeholder {
  color: color-mix(in srgb, var(--fg) 35%, transparent);
  font-style: italic;
}

/* Reveal toggle */
.open-reveal {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  width: 100%;
  padding: 10px;
  margin-top: 12px;
  background: color-mix(in srgb, #14b8a6 8%, var(--bg));
  border: 1px dashed color-mix(in srgb, #14b8a6 25%, transparent);
  border-radius: 7px;
  color: #14b8a6;
  font-size: 13px;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.15s ease;
}

.open-reveal:hover {
  background: color-mix(in srgb, #14b8a6 14%, var(--bg));
  border-style: solid;
}

.open-reveal-icon {
  transition: transform 0.3s ease;
}

.open-card.revealed .open-reveal-icon {
  transform: rotate(180deg);
}

.open-reveal-text::after {
  content: 'Show Model Answer';
}

.open-card.revealed .open-reveal-text::after {
  content: 'Hide Answer';
}

/* Model answer */
.open-answer {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.35s ease;
  background: color-mix(in srgb, #14b8a6 3%, var(--bg));
  border-top: 1px solid transparent;
}

.open-card.revealed .open-answer {
  max-height: 2000px;
  border-top: 1px solid color-mix(in srgb, #14b8a6 15%, transparent);
}

.open-answer-inner {
  padding: 0 18px;
  opacity: 0;
  max-height: 0;
  overflow: hidden;
  transition: all 0.3s ease 0.1s;
}

.open-card.revealed .open-answer-inner {
  padding: 14px 18px 16px;
  opacity: 1;
  max-height: 2000px;
}

.open-answer-label {
  font-size: 11px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.4px;
  color: var(--exam-correct);
  margin-bottom: 8px;
  display: flex;
  align-items: center;
  gap: 6px;
}

.open-answer-label::after {
  content: '';
  flex: 1;
  height: 1px;
  background: linear-gradient(90deg, color-mix(in srgb, var(--exam-correct) 25%, transparent), transparent);
}

.open-answer-content {
  font-size: 14px;
  line-height: 1.75;
  color: var(--fg);
}

.open-answer-content p {
  margin: 0 0 10px 0;
}

.open-answer-content p:last-child {
  margin-bottom: 0;
}

.open-answer-content ul,
.open-answer-content ol {
  margin: 8px 0;
  padding-left: 20px;
}

.open-answer-content li {
  margin: 4px 0;
}

.open-answer-content code {
  background: var(--inline-code-bg);
  padding: 1px 5px;
  border-radius: 4px;
  font-size: 0.9em;
}

/* Calculation steps styling */
.open-calc-step {
  padding: 8px 12px;
  margin: 8px 0;
  background: color-mix(in srgb, #f59e0b 6%, var(--bg));
  border-left: 3px solid #f59e0b;
  border-radius: 0 6px 6px 0;
  font-family: 'KaTeX_Math', serif;
  font-size: 14px;
}

/* ============================================
   Topic Variants (reuse in data-topic)
   ============================================ */

.exam-set[data-topic="ngs"]       { --exam-accent: #3b82f6; --exam-accent-light: #60a5fa; --exam-accent-dark: #2563eb; }
.exam-set[data-topic="assembly"]  { --exam-accent: #8b5cf6; --exam-accent-light: #a78bfa; --exam-accent-dark: #7c3aed; }
.exam-set[data-topic="gwas"]     { --exam-accent: #ec4899; --exam-accent-light: #f472b6; --exam-accent-dark: #db2777; }
.exam-set[data-topic="popgen"]   { --exam-accent: #f97316; --exam-accent-light: #fb923c; --exam-accent-dark: #ea580c; }
.exam-set[data-topic="genotyping"] { --exam-accent: #14b8a6; --exam-accent-light: #2dd4bf; --exam-accent-dark: #0d9488; }
.exam-set[data-topic="annotation"] { --exam-accent: #06b6d4; --exam-accent-light: #22d3ee; --exam-accent-dark: #0891b2; }
.exam-set[data-topic="variation"]  { --exam-accent: #84cc16; --exam-accent-light: #a3e635; --exam-accent-dark: #65a30d; }
.exam-set[data-topic="project"]    { --exam-accent: #6366f1; --exam-accent-light: #818cf8; --exam-accent-dark: #4f46e5; }

/* ============================================
   Mobile
   ============================================ */

@media (max-width: 768px) {
  .exam-set {
    padding: 16px;
    margin: 24px 0;
  }

  .exam-set-header {
    flex-direction: column;
    align-items: flex-start;
  }

  .mcq-body, .open-body {
    padding: 10px 14px 14px;
  }

  .mcq-head, .open-head {
    padding: 12px 14px 0;
  }

  .mcq-option {
    padding: 8px 10px;
    font-size: 13px;
  }

  .open-scratch {
    min-height: 60px;
  }
}

/* ============================================
   Print
   ============================================ */

@media print {
  .mcq-card, .open-card {
    break-inside: avoid;
    box-shadow: none;
    border: 1px solid #ccc;
  }

  .mcq-check-btn,
  .open-reveal {
    display: none;
  }

  .mcq-explanation,
  .open-answer {
    max-height: none !important;
  }

  .mcq-explanation-inner,
  .open-answer-inner {
    max-height: none !important;
    opacity: 1 !important;
    padding: 14px 18px !important;
  }

  .open-scratch {
    display: none;
  }
}