/* ============================================== */
/* GCSE Maths - Specific Styles                   */
/* ============================================== */

/* ============================================== */
/* TIER BADGES (Foundation / Higher)              */
/* ============================================== */

.tier-badge {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 2px 8px;
  border-radius: 12px;
  font-size: 0.7rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.5px;
  margin-left: 8px;
}

.tier-foundation {
  background: rgba(34, 197, 94, 0.15);
  color: #22c55e;
  border: 1px solid rgba(34, 197, 94, 0.3);
}

.tier-higher {
  background: rgba(139, 92, 246, 0.15);
  color: #8b5cf6;
  border: 1px solid rgba(139, 92, 246, 0.3);
}

.tier-both {
  background: linear-gradient(135deg, rgba(34, 197, 94, 0.15), rgba(139, 92, 246, 0.15));
  color: var(--text-primary);
  border: 1px solid var(--border-light);
}

/* ============================================== */
/* TIER FILTER (Sidebar)                          */
/* ============================================== */

.tier-filter {
  display: flex;
  gap: 12px;
  padding: 12px 16px;
  border-bottom: 1px solid var(--border-light);
}

.tier-toggle-label {
  display: flex;
  align-items: center;
  gap: 6px;
  cursor: pointer;
  user-select: none;
}

.tier-toggle-label input[type="checkbox"] {
  display: none;
}

.tier-toggle-label .tier-badge {
  opacity: 0.4;
  transition: opacity 0.2s;
}

.tier-toggle-label input[type="checkbox"]:checked + .tier-badge {
  opacity: 1;
}

/* ============================================== */
/* HIGHER-ONLY CONTENT BLOCKS                     */
/* ============================================== */

.higher-only {
  position: relative;
  border-left: 3px solid #8b5cf6;
  padding-left: var(--space-md);
  margin: var(--space-md) 0;
}

.higher-only::before {
  content: 'Higher Only';
  position: absolute;
  top: -8px;
  left: 12px;
  background: #8b5cf6;
  color: white;
  padding: 2px 8px;
  border-radius: 4px;
  font-size: 0.7rem;
  font-weight: 600;
  text-transform: uppercase;
}

/* ============================================== */
/* PAPER FILTER (Calculator / Non-Calculator)     */
/* ============================================== */

.paper-filter {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 12px 20px;
  margin-bottom: 20px;
  background: var(--bg-card);
  border-radius: var(--radius-md);
  flex-wrap: wrap;
}

.filter-label {
  color: var(--text-muted);
  font-size: 0.85rem;
}

.filter-btn {
  padding: 6px 12px;
  border: 1px solid var(--border-light);
  border-radius: 20px;
  background: transparent;
  color: var(--text-secondary);
  font-size: 0.85rem;
  cursor: pointer;
  transition: all 0.2s;
}

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

.filter-btn.active {
  background: var(--accent);
  border-color: var(--accent);
  color: white;
}

/* ============================================== */
/* MATH FRACTIONS (CSS-only rendering)            */
/* ============================================== */

.math-fraction {
  display: inline-flex;
  flex-direction: column;
  text-align: center;
  vertical-align: middle;
  margin: 0 4px;
}

.math-fraction .num {
  border-bottom: 1px solid currentColor;
  padding: 0 6px 2px;
  font-size: 0.9em;
}

.math-fraction .den {
  padding: 2px 6px 0;
  font-size: 0.9em;
}

/* Larger fractions for formulas */
.formula .math-fraction {
  font-size: 1.1em;
}

.formula .math-fraction .num,
.formula .math-fraction .den {
  padding: 2px 8px;
}

/* ============================================== */
/* FORMULA CARDS                                  */
/* ============================================== */

.formula-card {
  background: var(--bg-card);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-md);
  padding: var(--space-md);
  margin: var(--space-md) 0;
}

.formula-card .formula {
  font-family: var(--font-mono);
  font-size: 1.2em;
  color: var(--accent);
  text-align: center;
  padding: var(--space-sm) 0;
}

/* ============================================== */
/* WORKED EXAMPLES (Step-by-step reveal)          */
/* ============================================== */

.box-worked-example {
  border-left-color: #2563EB !important;
}

.box-worked-example h4 {
  color: #2563EB;
}

.worked-problem {
  background: rgba(59, 130, 246, 0.1);
  border-radius: var(--radius-md);
  padding: var(--space-md);
  margin-bottom: var(--space-md);
}

.worked-problem .problem-text {
  font-size: 1.1em;
  font-family: var(--font-mono);
  margin: 0;
}

.worked-solution {
  border-left: 3px solid rgba(59, 130, 246, 0.3);
  padding-left: var(--space-md);
  margin-top: var(--space-md);
}

/* Solution steps */
.solution-step {
  margin-bottom: var(--space-sm);
}

.solution-step > summary {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  cursor: pointer;
  padding: var(--space-sm) var(--space-md);
  background: var(--bg-card);
  border-radius: var(--radius-sm);
  transition: background 0.2s;
  list-style: none;
}

.solution-step > summary::-webkit-details-marker {
  display: none;
}

.solution-step > summary:hover {
  background: var(--bg-hover);
}

.solution-step[open] > summary {
  background: rgba(59, 130, 246, 0.1);
}

.step-num {
  background: #2563EB;
  color: white;
  padding: 2px 10px;
  border-radius: 12px;
  font-size: 0.75rem;
  font-weight: 600;
  white-space: nowrap;
}

.step-content {
  padding: var(--space-sm) var(--space-md);
  padding-left: calc(var(--space-md) + 50px);
}

.step-content .working {
  font-family: var(--font-mono);
  font-size: 1.05em;
  margin: var(--space-xs) 0;
  color: var(--text-primary);
}

.step-content .step-explanation {
  color: var(--text-muted);
  font-size: 0.9em;
  font-style: italic;
  margin-top: var(--space-xs);
}

/* Final answer box */
.solution-final {
  margin-top: var(--space-md);
  padding: var(--space-md);
  background: rgba(34, 197, 94, 0.1);
  border-radius: var(--radius-md);
  border-left: 4px solid #22c55e;
  display: flex;
  align-items: center;
  gap: var(--space-sm);
}

.final-label {
  color: var(--text-muted);
  font-weight: 500;
}

.final-answer {
  font-family: var(--font-mono);
  font-size: 1.2em;
  font-weight: 600;
  color: #22c55e;
}

/* ============================================== */
/* METHOD STEPS (Ordered list styling)            */
/* ============================================== */

.method-steps {
  counter-reset: step-counter;
  list-style: none;
  padding: 0;
  margin: var(--space-md) 0;
}

.method-steps li {
  counter-increment: step-counter;
  position: relative;
  padding-left: 40px;
  margin-bottom: var(--space-sm);
}

.method-steps li::before {
  content: counter(step-counter);
  position: absolute;
  left: 0;
  top: 0;
  width: 28px;
  height: 28px;
  background: var(--accent);
  color: white;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.85rem;
  font-weight: 600;
}

/* ============================================== */
/* COMMON MISTAKES BOX                            */
/* ============================================== */

.box-tips .mistake-list {
  list-style: none;
  padding: 0;
  margin: 0;
}

.box-tips .mistake-list li {
  padding: var(--space-sm) var(--space-md);
  margin-bottom: var(--space-sm);
  background: var(--bg-card);
  border-radius: var(--radius-sm);
  border-left: 3px solid var(--border-light);
}

.mistake-wrong {
  display: inline-block;
  background: rgba(239, 68, 68, 0.2);
  color: #ef4444;
  padding: 2px 8px;
  border-radius: 4px;
  font-size: 0.75rem;
  font-weight: 600;
  margin-right: 8px;
}

.mistake-right {
  display: inline-block;
  background: rgba(34, 197, 94, 0.2);
  color: #22c55e;
  padding: 2px 8px;
  border-radius: 4px;
  font-size: 0.75rem;
  font-weight: 600;
  margin-right: 8px;
}

.mistake-why {
  display: block;
  color: var(--text-muted);
  font-size: 0.85em;
  margin-top: 4px;
  font-style: italic;
}

/* ============================================== */
/* PRACTICE DRILL LAUNCHER                        */
/* ============================================== */

.practice-launcher {
  background: linear-gradient(135deg, rgba(59, 130, 246, 0.1), rgba(139, 92, 246, 0.1));
  border: 1px dashed rgba(59, 130, 246, 0.3);
  border-radius: var(--radius-md);
  padding: var(--space-lg);
  margin: var(--space-lg) 0;
  text-align: center;
}

.practice-launcher h4 {
  color: var(--text-primary);
  margin-bottom: var(--space-xs);
}

.practice-launcher p {
  color: var(--text-muted);
  font-size: 0.9em;
  margin-bottom: var(--space-md);
}

.practice-drill-btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 12px 24px;
  background: linear-gradient(135deg, #2563EB, #8b5cf6);
  color: white;
  border: none;
  border-radius: var(--radius-md);
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  transition: transform 0.2s, box-shadow 0.2s;
}

.practice-drill-btn:hover {
  transform: translateY(-2px);
  box-shadow: 0 4px 12px rgba(59, 130, 246, 0.3);
}

.practice-drill-btn::before {
  content: '∞';
  font-size: 1.2em;
}

/* ============================================== */
/* EQUATION INPUT BUILDER                         */
/* ============================================== */

.equation-input {
  display: flex;
  flex-direction: column;
  gap: var(--space-sm);
  margin: var(--space-md) 0;
}

.equation-input .answer-field {
  width: 100%;
  padding: 12px 16px;
  font-family: var(--font-mono);
  font-size: 1.1em;
  border: 2px solid var(--border-light);
  border-radius: var(--radius-md);
  background: var(--bg-card);
  color: var(--text-primary);
  transition: border-color 0.2s;
}

.equation-input .answer-field:focus {
  outline: none;
  border-color: var(--accent);
}

.equation-helpers {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
}

.equation-helpers button {
  padding: 8px 12px;
  border: 1px solid var(--border-light);
  border-radius: var(--radius-sm);
  background: var(--bg-card);
  color: var(--text-primary);
  font-family: var(--font-mono);
  font-size: 1rem;
  cursor: pointer;
  transition: all 0.2s;
}

.equation-helpers button:hover {
  background: var(--accent);
  border-color: var(--accent);
  color: white;
}

/* ============================================== */
/* STEP INPUT (Structured mode for beginners)     */
/* ============================================== */

.step-input {
  background: var(--bg-card);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-md);
  padding: var(--space-md);
  margin: var(--space-md) 0;
}

.step-input .step {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  flex-wrap: wrap;
  margin-bottom: var(--space-sm);
}

.step-input .step-label {
  font-weight: 600;
  color: var(--text-muted);
  min-width: 60px;
}

.step-input select,
.step-input input {
  padding: 8px 12px;
  border: 1px solid var(--border-light);
  border-radius: var(--radius-sm);
  background: var(--bg-page);
  color: var(--text-primary);
  font-family: inherit;
}

.step-input .result {
  color: var(--text-muted);
}

.step-input .working-area {
  width: 100%;
  min-height: 120px;
  padding: var(--space-md);
  font-family: var(--font-mono);
  font-size: 1rem;
  line-height: 1.6;
  border: 1px solid var(--border-light);
  border-radius: var(--radius-md);
  background: var(--bg-page);
  color: var(--text-primary);
  resize: vertical;
}

/* ============================================== */
/* DIFFICULTY CONTROL                             */
/* ============================================== */

.difficulty-control {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  padding: var(--space-md);
  background: var(--bg-card);
  border-radius: var(--radius-md);
  margin: var(--space-md) 0;
}

.difficulty-control span {
  color: var(--text-muted);
  font-size: 0.9rem;
}

.difficulty-control button {
  padding: 6px 12px;
  border: 1px solid var(--border-light);
  border-radius: var(--radius-sm);
  background: transparent;
  color: var(--text-secondary);
  font-size: 0.85rem;
  cursor: pointer;
  transition: all 0.2s;
}

.difficulty-control button:hover {
  border-color: var(--accent);
  color: var(--accent);
}

.difficulty-control button.active {
  background: var(--accent);
  border-color: var(--accent);
  color: white;
}

/* ============================================== */
/* MARK SCHEME DISPLAY                            */
/* ============================================== */

.mark-scheme {
  background: var(--bg-card);
  border: 1px solid var(--border-light);
  border-radius: var(--radius-md);
  padding: var(--space-md);
  margin: var(--space-md) 0;
}

.mark-scheme .mark-point {
  display: flex;
  align-items: flex-start;
  gap: var(--space-sm);
  padding: var(--space-xs) 0;
}

.mark-scheme .marks {
  background: var(--accent);
  color: white;
  padding: 2px 8px;
  border-radius: 4px;
  font-size: 0.75rem;
  font-weight: 600;
  white-space: nowrap;
}

.mark-scheme .criteria {
  color: var(--text-secondary);
  font-size: 0.9rem;
}

/* ============================================== */
/* PLACEHOLDER NOTES                              */
/* ============================================== */

.placeholder-note {
  color: var(--text-muted);
  font-style: italic;
  text-align: center;
  padding: var(--space-xl);
  background: var(--bg-card);
  border-radius: var(--radius-md);
  border: 1px dashed var(--border-light);
}

/* ============================================== */
/* RESPONSIVE ADJUSTMENTS                         */
/* ============================================== */

@media (max-width: 768px) {
  .paper-filter {
    flex-direction: column;
    align-items: flex-start;
  }

  .filter-btn {
    flex: 1;
    text-align: center;
  }

  .equation-helpers {
    justify-content: center;
  }

  .step-input .step {
    flex-direction: column;
    align-items: flex-start;
  }

  .step-content {
    padding-left: var(--space-md);
  }

  .difficulty-control {
    flex-wrap: wrap;
  }
}

/* ============================================== */
/* FORMULA SHEET BUTTON                           */
/* ============================================== */

.formula-sheet-btn {
  display: inline-flex;
  align-items: center;
  gap: var(--space-sm);
  padding: var(--space-sm) var(--space-lg);
  background: linear-gradient(135deg, #f59e0b, #d97706);
  color: white;
  border: none;
  border-radius: 25px;
  font-size: var(--font-sm);
  font-weight: 600;
  cursor: pointer;
  transition: all var(--transition-fast);
  text-decoration: none;
  min-height: var(--touch-target-min);
}

.formula-sheet-btn:hover {
  transform: translateY(-2px);
  box-shadow: 0 4px 15px rgba(245, 158, 11, 0.4);
  color: white;
  text-decoration: none;
}

.formula-sheet-btn::before {
  content: 'f(x)';
  font-family: var(--font-mono);
  font-style: italic;
  font-size: 0.9em;
}