/* ==========================================================================
   INTERACTIVE EXERCISE WIDGETS & QUIZ CARDS
   ========================================================================== */

/* Category Filter Bar */
.filter-container {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-bottom: 28px;
  flex-wrap: wrap;
  padding: 12px 16px;
  background-color: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
}

.filter-label {
  font-size: 0.78rem;
  font-weight: 700;
  text-transform: uppercase;
  color: var(--text-subtle);
  margin-right: 4px;
}

.filter-chip {
  background: #ffffff;
  border: 1px solid var(--border-color);
  color: var(--text-muted);
  padding: 5px 12px;
  border-radius: 9999px;
  font-size: 0.8rem;
  font-weight: 600;
  cursor: pointer;
  transition: all var(--transition-fast);
  display: inline-flex;
  align-items: center;
  gap: 6px;
}

.filter-chip:hover {
  border-color: var(--accent-primary);
  color: var(--accent-primary);
}

.filter-chip.active {
  background-color: var(--accent-primary);
  border-color: var(--accent-primary);
  color: #ffffff;
}

.filter-chip .chip-count {
  font-size: 0.72rem;
  background: rgba(0, 0, 0, 0.08);
  padding: 1px 6px;
  border-radius: 9999px;
}

.filter-chip.active .chip-count {
  background: rgba(255, 255, 255, 0.25);
  color: #ffffff;
}

/* Score / Progress Banner */
.stats-banner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 16px 20px;
  background: linear-gradient(135deg, #eff6ff 0%, #f0fdf4 100%);
  border: 1px solid var(--accent-border);
  border-radius: var(--radius-md);
  margin-bottom: 28px;
}

.stats-info {
  display: flex;
  align-items: center;
  gap: 16px;
}

.stats-metric {
  display: flex;
  flex-direction: column;
}

.stats-value {
  font-size: 1.3rem;
  font-weight: 700;
  font-family: var(--font-mono);
  color: var(--accent-primary);
}

.stats-label {
  font-size: 0.75rem;
  color: var(--text-subtle);
  font-weight: 600;
  text-transform: uppercase;
}

.stats-actions {
  display: flex;
  gap: 8px;
}

.btn-sm {
  background: #ffffff;
  border: 1px solid var(--border-color);
  color: var(--text-muted);
  padding: 6px 12px;
  font-size: 0.78rem;
  font-weight: 600;
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: all var(--transition-fast);
}

.btn-sm:hover {
  background-color: var(--bg-tertiary);
  color: var(--text-main);
}

/* Question Card */
.exercise-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 24px;
  margin-bottom: 24px;
  box-shadow: var(--shadow-sm);
  transition: all var(--transition-fast);
  position: relative;
}

.exercise-card:hover {
  box-shadow: var(--shadow-md);
  border-color: #cbd5e1;
}

.exercise-header {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 12px;
  margin-bottom: 14px;
}

.exercise-badge-group {
  display: flex;
  align-items: center;
  gap: 8px;
}

.badge-qnum {
  font-family: var(--font-mono);
  font-size: 0.82rem;
  font-weight: 700;
  color: #1e293b;
  background: #f1f5f9;
  padding: 3px 8px;
  border-radius: 4px;
}

.badge-type {
  font-size: 0.72rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  padding: 3px 8px;
  border-radius: 4px;
}

.type-mc { background: #e0f2fe; color: #0369a1; }
.type-tf { background: #fef3c7; color: #92400e; }
.type-fill { background: #f3e8ff; color: #6b21a8; }
.type-short { background: #f1f5f9; color: #475569; }
.type-algo { background: #dbeafe; color: #1d4ed8; }
.type-predict { background: #ffedd5; color: #c2410c; }
.type-error { background: #fee2e2; color: #b91c1c; }
.type-challenge { background: #dcfce7; color: #15803d; }

/* Bloom Taxonomy Badges */
.badge-bloom {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  font-weight: 700;
  padding: 3px 8px;
  border-radius: 4px;
  text-transform: uppercase;
  letter-spacing: 0.03em;
  display: inline-flex;
  align-items: center;
  gap: 4px;
}

.badge-bloom.bloom-lvl-1 { background: #f0fdf4; color: #166534; border: 1px solid #bbf7d0; }
.badge-bloom.bloom-lvl-2 { background: #f0f9ff; color: #0369a1; border: 1px solid #bae6fd; }
.badge-bloom.bloom-lvl-3 { background: #f5f3ff; color: #6d28d9; border: 1px solid #ddd6fe; }
.badge-bloom.bloom-lvl-4 { background: #fffbeb; color: #b45309; border: 1px solid #fde68a; }
.badge-bloom.bloom-lvl-5 { background: #fff7ed; color: #c2410c; border: 1px solid #ffedd5; }
.badge-bloom.bloom-lvl-6 { background: #fff1f2; color: #be123c; border: 1px solid #fecdd3; }

.question-text {
  font-size: 1.02rem;
  line-height: 1.65;
  color: var(--text-main);
  margin-bottom: 16px;
}

.question-text p:last-child {
  margin-bottom: 0;
}

/* Multiple Choice & True/False Interactive Options */
.options-grid {
  display: flex;
  flex-direction: column;
  gap: 10px;
  margin: 16px 0;
}

.quiz-option {
  display: flex;
  align-items: flex-start;
  gap: 12px;
  padding: 12px 16px;
  background-color: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: all var(--transition-fast);
  font-size: 0.94rem;
  line-height: 1.5;
  user-select: none;
}

.quiz-option:hover {
  background-color: var(--accent-light);
  border-color: var(--accent-border);
}

.quiz-option.selected {
  background-color: var(--accent-light);
  border-color: var(--accent-primary);
  font-weight: 500;
}

.quiz-option.correct {
  background-color: var(--success-bg) !important;
  border-color: var(--success-border) !important;
  color: var(--success-text) !important;
}

.quiz-option.incorrect {
  background-color: var(--danger-bg) !important;
  border-color: var(--danger-border) !important;
  color: var(--danger-text) !important;
}

.option-indicator {
  font-family: var(--font-mono);
  font-weight: 700;
  font-size: 0.85rem;
  width: 24px;
  height: 24px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border-radius: 50%;
  background: #e2e8f0;
  color: var(--text-muted);
  flex-shrink: 0;
  margin-top: 1px;
}

.quiz-option.selected .option-indicator {
  background: var(--accent-primary);
  color: #ffffff;
}

.quiz-option.correct .option-indicator {
  background: #16a34a;
  color: #ffffff;
}

.quiz-option.incorrect .option-indicator {
  background: #dc2626;
  color: #ffffff;
}

/* Solution / Explanation Drawer */
.solution-toggle-btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  background-color: #f8fafc;
  border: 1px solid var(--border-color);
  color: var(--text-muted);
  padding: 7px 14px;
  border-radius: var(--radius-sm);
  font-size: 0.84rem;
  font-weight: 600;
  cursor: pointer;
  transition: all var(--transition-fast);
  margin-top: 8px;
}

.solution-toggle-btn:hover {
  background-color: var(--bg-tertiary);
  color: var(--accent-primary);
  border-color: var(--accent-border);
}

.solution-toggle-btn .toggle-arrow {
  transition: transform var(--transition-fast);
}

.solution-toggle-btn.open .toggle-arrow {
  transform: rotate(180deg);
}

.solution-drawer {
  display: none;
  margin-top: 14px;
  padding: 16px 18px;
  background-color: #f8fafc;
  border: 1px solid var(--border-color);
  border-left: 4px solid var(--accent-primary);
  border-radius: var(--radius-sm);
  font-size: 0.92rem;
  line-height: 1.6;
}

.solution-drawer.open {
  display: block;
  animation: fadeIn 0.2s ease-out;
}

.solution-title {
  font-weight: 700;
  color: var(--text-main);
  font-size: 0.88rem;
  margin-bottom: 8px;
  display: flex;
  align-items: center;
  gap: 6px;
}

/* Challenge Box */
.challenge-meta {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 12px;
}

.challenge-title {
  font-size: 1.15rem;
  font-weight: 700;
  color: var(--text-main);
}

/* Catalog / Index Grid */
.catalog-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 20px;
  margin-top: 32px;
}

.chapter-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 20px;
  text-decoration: none;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  transition: all var(--transition-fast);
  box-shadow: var(--shadow-sm);
}

.chapter-card:hover {
  border-color: var(--accent-primary);
  transform: translateY(-3px);
  box-shadow: var(--shadow-md);
}

.card-num-badge {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  font-weight: 700;
  color: var(--accent-primary);
  background: var(--accent-light);
  padding: 2px 8px;
  border-radius: 4px;
  width: fit-content;
  margin-bottom: 10px;
}

.card-title {
  font-size: 1.05rem;
  font-weight: 700;
  color: var(--text-main);
  line-height: 1.4;
  margin-bottom: 12px;
}

.card-stats {
  display: flex;
  align-items: center;
  justify-content: space-between;
  font-size: 0.78rem;
  color: var(--text-subtle);
  border-top: 1px solid var(--border-color);
  padding-top: 10px;
  margin-top: auto;
}

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(-4px); }
  to { opacity: 1; transform: translateY(0); }
}


/* ==========================================================================
   TIME-BASED PROGRESSIVE UNLOCK & INSTRUCTOR MODE STYLES
   ========================================================================== */

/* Locked Chapter Card */
.chapter-card.locked {
  background: #f8fafc;
  border-color: #cbd5e1;
  opacity: 0.82;
  cursor: pointer;
  position: relative;
  overflow: hidden;
}

.chapter-card.locked:hover {
  transform: none;
  box-shadow: var(--shadow-sm);
  border-color: #94a3b8;
}

.card-lock-badge {
  display: inline-flex;
  align-items: center;
  gap: 5px;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  font-weight: 700;
  color: #b45309;
  background: #fef3c7;
  padding: 3px 8px;
  border-radius: 4px;
  margin-bottom: 8px;
  width: fit-content;
}

.card-week-badge {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  font-size: 0.72rem;
  font-weight: 600;
  color: #475569;
  background: #e2e8f0;
  padding: 2px 7px;
  border-radius: 4px;
}

.nav-link.locked {
  color: #94a3b8;
}

.nav-link.locked .nav-chapter-num {
  background-color: #f1f5f9;
  color: #94a3b8;
}

.nav-lock-icon {
  margin-left: auto;
  font-size: 0.75rem;
  color: #94a3b8;
}

/* Instructor Banner */
.instructor-banner {
  display: none;
  background: #fef08a;
  border-bottom: 1px solid #facc15;
  color: #854d0e;
  padding: 8px 16px;
  font-size: 0.82rem;
  font-weight: 600;
  text-align: center;
  position: sticky;
  top: 0;
  z-index: 1001;
}

.instructor-banner.active {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 12px;
}

.instructor-banner button {
  background: #854d0e;
  color: #ffffff;
  border: none;
  padding: 3px 10px;
  border-radius: 4px;
  font-size: 0.75rem;
  font-weight: 700;
  cursor: pointer;
}

.btn-instructor-toggle {
  background: #f8fafc;
  border: 1px solid var(--border-color);
  color: var(--text-muted);
  padding: 4px 10px;
  border-radius: var(--radius-sm);
  font-size: 0.76rem;
  font-weight: 600;
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  gap: 6px;
  transition: all var(--transition-fast);
}

.btn-instructor-toggle:hover {
  background: #ffffff;
  color: var(--accent-primary);
  border-color: var(--accent-border);
}

/* Locked Screen Guard Card (inside locked chapter) */
.locked-screen-card {
  display: none;
  text-align: center;
  padding: 60px 32px;
  background: #ffffff;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-md);
  margin: 40px auto;
  max-width: 580px;
}

.locked-screen-card.visible {
  display: block;
}

.locked-icon-large {
  font-size: 3.5rem;
  margin-bottom: 16px;
  display: block;
}

.locked-screen-title {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--text-main);
  margin-bottom: 8px;
}

.locked-screen-desc {
  font-size: 1.0rem;
  color: var(--text-muted);
  line-height: 1.6;
  margin-bottom: 24px;
}

.unlock-date-pill {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-family: var(--font-mono);
  font-size: 0.95rem;
  font-weight: 700;
  color: #b45309;
  background: #fef3c7;
  padding: 8px 18px;
  border-radius: 9999px;
  margin-bottom: 28px;
  border: 1px solid #fde68a;
}

.passcode-form {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  margin-top: 20px;
  flex-wrap: wrap;
}

.passcode-input {
  padding: 8px 14px;
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  font-size: 0.9rem;
  font-family: var(--font-mono);
  outline: none;
}

.passcode-input:focus {
  border-color: var(--accent-primary);
  box-shadow: 0 0 0 2px var(--accent-light);
}

/* Modal */
.modal-overlay {
  display: none;
  position: fixed;
  inset: 0;
  background: rgba(15, 23, 42, 0.6);
  backdrop-filter: blur(4px);
  z-index: 2000;
  align-items: center;
  justify-content: center;
  padding: 20px;
}

.modal-overlay.active {
  display: flex;
}

.modal-card {
  background: #ffffff;
  border-radius: var(--radius-lg);
  padding: 28px;
  width: 100%;
  max-width: 440px;
  box-shadow: var(--shadow-lg);
  position: relative;
}

.modal-title {
  font-size: 1.25rem;
  font-weight: 700;
  margin-bottom: 8px;
  display: flex;
  align-items: center;
  gap: 8px;
}

.modal-close {
  position: absolute;
  top: 18px;
  right: 18px;
  background: transparent;
  border: none;
  font-size: 1.2rem;
  cursor: pointer;
  color: var(--text-subtle);
}