/* ─── Glass Card ─────────────────────────────────────────── */
.card {
  background: var(--gradient-card);
  border: 1px solid var(--glass-border);
  border-radius: var(--radius-lg);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  padding: var(--space-xl);
  transition: border-color var(--transition-normal),
              transform var(--transition-normal),
              box-shadow var(--transition-normal);
}

.card:hover {
  border-color: var(--glass-border-hover);
  transform: translateY(-2px);
  box-shadow: var(--shadow-lg);
}

.card-sm {
  padding: var(--space-lg);
  border-radius: var(--radius-md);
}

/* ─── Buttons ────────────────────────────────────────────── */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-sm);
  padding: 12px 24px;
  border: none;
  border-radius: var(--radius-full);
  font-family: var(--font-system);
  font-size: 0.95rem;
  font-weight: 600;
  cursor: pointer;
  transition: all var(--transition-fast);
  white-space: nowrap;
  text-decoration: none;
  -webkit-tap-highlight-color: transparent;
}

.btn:disabled {
  opacity: 0.4;
  cursor: not-allowed;
  transform: none !important;
}

.btn-primary {
  background: var(--accent-blue);
  color: #ffffff;
}
.btn-primary:hover:not(:disabled) {
  background: var(--accent-blue-hover);
  transform: scale(1.02);
  box-shadow: 0 4px 20px rgba(0, 113, 227, 0.4);
}

.btn-secondary {
  background: rgba(255, 255, 255, 0.1);
  color: var(--text-primary);
  border: 1px solid var(--glass-border);
}
.btn-secondary:hover:not(:disabled) {
  background: rgba(255, 255, 255, 0.15);
  border-color: var(--glass-border-hover);
  transform: scale(1.02);
}

.btn-ghost {
  background: transparent;
  color: var(--text-secondary);
  border: 1px solid transparent;
}
.btn-ghost:hover:not(:disabled) {
  background: rgba(255, 255, 255, 0.05);
  color: var(--text-primary);
}

.btn-danger {
  background: var(--accent-red);
  color: #ffffff;
}
.btn-danger:hover:not(:disabled) {
  opacity: 0.9;
  transform: scale(1.02);
}

.btn-success {
  background: var(--accent-green);
  color: #000;
}

.btn-lg {
  padding: 16px 36px;
  font-size: 1.05rem;
  border-radius: var(--radius-full);
}

.btn-sm {
  padding: 8px 16px;
  font-size: 0.85rem;
}

/* ─── Form Elements ──────────────────────────────────────── */
.form-group {
  display: flex;
  flex-direction: column;
  gap: var(--space-sm);
}

.form-label {
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--text-secondary);
  letter-spacing: 0.02em;
  text-transform: uppercase;
}

.form-input {
  background: rgba(255, 255, 255, 0.06);
  border: 1px solid var(--glass-border);
  border-radius: var(--radius-md);
  padding: 14px 18px;
  color: var(--text-primary);
  font-family: var(--font-system);
  font-size: 1rem;
  transition: border-color var(--transition-fast), background var(--transition-fast);
  outline: none;
}

.form-input::placeholder { color: var(--text-tertiary); }

.form-input:focus {
  border-color: var(--accent-blue);
  background: rgba(0, 113, 227, 0.05);
  box-shadow: 0 0 0 3px rgba(0, 113, 227, 0.1);
}

.form-error {
  font-size: 0.82rem;
  color: var(--accent-red);
  margin-top: 2px;
}

/* ─── Badge ──────────────────────────────────────────────── */
.badge {
  display: inline-flex;
  align-items: center;
  padding: 3px 10px;
  border-radius: var(--radius-full);
  font-size: 0.75rem;
  font-weight: 600;
  letter-spacing: 0.03em;
}

.badge-blue   { background: var(--accent-blue-dim);  color: #40a9ff; }
.badge-green  { background: var(--accent-green-dim); color: var(--accent-green); }
.badge-red    { background: var(--accent-red-dim);   color: var(--accent-red); }
.badge-purple { background: rgba(191,90,242,0.15);   color: var(--accent-purple); }
.badge-yellow { background: rgba(255,214,10,0.15);   color: var(--accent-yellow); }

/* ─── Progress Bar ───────────────────────────────────────── */
.progress-bar-wrap {
  width: 100%;
  background: rgba(255, 255, 255, 0.08);
  border-radius: var(--radius-full);
  height: 4px;
  overflow: hidden;
}

.progress-bar-fill {
  height: 100%;
  background: var(--gradient-blue);
  border-radius: var(--radius-full);
  transition: width 0.4s cubic-bezier(0.4, 0, 0.2, 1);
}

/* ─── Question Card ──────────────────────────────────────── */
.question-card {
  background: var(--gradient-card);
  border: 1px solid var(--glass-border);
  border-radius: var(--radius-lg);
  padding: var(--space-xl);
  backdrop-filter: blur(20px);
}

.question-text {
  font-size: 1.05rem;
  color: var(--text-primary);
  line-height: 1.7;
  margin-bottom: var(--space-lg);
  white-space: pre-wrap;
}

.question-image {
  width: 100%;
  max-width: 600px;
  border-radius: var(--radius-md);
  margin-bottom: var(--space-lg);
  border: 1px solid var(--glass-border);
}

/* ─── Answer Options ─────────────────────────────────────── */
.options-grid {
  display: flex;
  flex-direction: column;
  gap: var(--space-sm);
}

.option-btn {
  display: flex;
  align-items: flex-start;
  gap: var(--space-md);
  padding: var(--space-md) var(--space-lg);
  background: rgba(255, 255, 255, 0.04);
  border: 1px solid var(--glass-border);
  border-radius: var(--radius-md);
  color: var(--text-primary);
  font-family: var(--font-system);
  font-size: 0.97rem;
  text-align: left;
  cursor: pointer;
  transition: all var(--transition-fast);
  line-height: 1.5;
}

.option-btn:hover:not(:disabled) {
  background: rgba(255, 255, 255, 0.08);
  border-color: var(--glass-border-hover);
  transform: translateX(4px);
}

.option-letter {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 28px;
  height: 28px;
  min-width: 28px;
  background: rgba(255,255,255,0.08);
  border-radius: 50%;
  font-weight: 700;
  font-size: 0.85rem;
  flex-shrink: 0;
  margin-top: 1px;
}

.option-btn.selected {
  background: var(--accent-blue-dim);
  border-color: var(--accent-blue);
}
.option-btn.selected .option-letter {
  background: var(--accent-blue);
  color: white;
}

.option-btn.correct {
  background: var(--accent-green-dim);
  border-color: var(--accent-green);
}
.option-btn.correct .option-letter {
  background: var(--accent-green);
  color: #000;
}

.option-btn.wrong {
  background: var(--accent-red-dim);
  border-color: var(--accent-red);
}
.option-btn.wrong .option-letter {
  background: var(--accent-red);
  color: white;
}

.option-btn:disabled { cursor: default; }

/* ─── Explanation Panel ──────────────────────────────────── */
.explanation-panel {
  margin-top: var(--space-lg);
  background: rgba(255, 255, 255, 0.03);
  border: 1px solid var(--glass-border);
  border-left: 3px solid var(--accent-blue);
  border-radius: var(--radius-md);
  padding: var(--space-lg);
  animation: fadeInDown 0.3s ease;
}

.explanation-panel h4 {
  color: var(--accent-blue);
  font-size: 0.9rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: var(--space-sm);
}

.explanation-panel p {
  color: var(--text-secondary);
  font-size: 0.95rem;
  white-space: pre-wrap;
  line-height: 1.7;
}

.explanation-body {
  color: var(--text-secondary);
  font-size: 0.95rem;
  line-height: 1.8;
}

.explanation-body strong {
  color: var(--text-primary);
  font-weight: 600;
}

/* ─── Stats Card ─────────────────────────────────────────── */
.stat-card {
  text-align: center;
  padding: var(--space-xl);
}

.stat-number {
  font-size: clamp(2rem, 4vw, 3rem);
  font-weight: 800;
  letter-spacing: -0.04em;
  background: var(--gradient-hero);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  line-height: 1;
}

.stat-label {
  color: var(--text-secondary);
  font-size: 0.9rem;
  margin-top: var(--space-sm);
}

/* ─── Modal ──────────────────────────────────────────────── */
.modal-overlay {
  position: fixed;
  top: 0; left: 0; right: 0; bottom: 0;
  background: rgba(0, 0, 0, 0.7);
  backdrop-filter: blur(8px);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 2000;
  padding: var(--space-lg);
  animation: fadeIn 0.2s ease;
}

.modal {
  background: #161616;
  border: 1px solid var(--glass-border);
  border-radius: var(--radius-xl);
  padding: var(--space-xl);
  max-width: 480px;
  width: 100%;
  animation: scaleIn 0.25s cubic-bezier(0.34, 1.56, 0.64, 1);
}

.modal h3 {
  margin-bottom: var(--space-md);
}

.modal p {
  margin-bottom: var(--space-xl);
}

.modal-actions {
  display: flex;
  gap: var(--space-sm);
  justify-content: flex-end;
}

/* ─── Timer ──────────────────────────────────────────────── */
.timer {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  font-size: 1.1rem;
  font-weight: 700;
  font-variant-numeric: tabular-nums;
  color: var(--text-primary);
  padding: var(--space-sm) var(--space-md);
  background: var(--bg-card);
  border: 1px solid var(--glass-border);
  border-radius: var(--radius-full);
}

.timer.warning { color: var(--accent-yellow); border-color: rgba(255, 214, 10, 0.3); }
.timer.danger  { color: var(--accent-red);    border-color: rgba(255, 69, 58, 0.3); animation: pulse 1s infinite; }

@keyframes pulse {
  0%, 100% { opacity: 1; }
  50%       { opacity: 0.6; }
}

/* ─── Answer Palette (Mock Exam) ─────────────────────────── */
.answer-palette {
  display: grid;
  grid-template-columns: repeat(10, 1fr);
  gap: 6px;
}

.palette-btn {
  aspect-ratio: 1;
  border-radius: 50%;
  border: 1px solid var(--glass-border);
  background: rgba(255,255,255,0.04);
  color: var(--text-secondary);
  font-size: 0.75rem;
  font-weight: 600;
  cursor: pointer;
  transition: all var(--transition-fast);
  display: flex;
  align-items: center;
  justify-content: center;
  min-width: 0;
}

.palette-btn:hover {
  background: rgba(255,255,255,0.1);
  color: var(--text-primary);
}

.palette-btn.answered {
  background: var(--accent-blue-dim);
  border-color: var(--accent-blue);
  color: var(--accent-blue);
}

.palette-btn.current {
  background: var(--accent-blue);
  border-color: var(--accent-blue);
  color: white;
}

/* ─── Score Summary ──────────────────────────────────────── */
.score-circle {
  width: 140px;
  height: 140px;
  border-radius: 50%;
  background: conic-gradient(var(--accent-blue) var(--pct, 0%), rgba(255,255,255,0.06) 0%);
  display: flex;
  align-items: center;
  justify-content: center;
  position: relative;
  margin: 0 auto;
}

.score-circle::before {
  content: '';
  position: absolute;
  width: 110px;
  height: 110px;
  border-radius: 50%;
  background: var(--bg-primary);
}

.score-circle-text {
  position: relative;
  z-index: 1;
  text-align: center;
}

.score-circle-text .score-num {
  font-size: 1.8rem;
  font-weight: 800;
  letter-spacing: -0.04em;
}

.score-circle-text .score-denom {
  font-size: 0.8rem;
  color: var(--text-secondary);
}

/* ─── Filter Tabs ────────────────────────────────────────── */
.filter-tabs {
  display: flex;
  gap: var(--space-xs);
  background: rgba(255,255,255,0.04);
  border-radius: var(--radius-full);
  padding: 4px;
  width: fit-content;
}

.filter-tab {
  padding: 8px 20px;
  border-radius: var(--radius-full);
  border: none;
  background: transparent;
  color: var(--text-secondary);
  font-family: var(--font-system);
  font-size: 0.9rem;
  font-weight: 500;
  cursor: pointer;
  transition: all var(--transition-fast);
}

.filter-tab.active {
  background: var(--accent-blue);
  color: white;
}

.filter-tab:hover:not(.active) {
  color: var(--text-primary);
}

/* ─── Review Question Item ───────────────────────────────── */
.review-item {
  background: var(--bg-card);
  border: 1px solid var(--glass-border);
  border-radius: var(--radius-md);
  overflow: hidden;
  transition: border-color var(--transition-fast);
}

.review-item.correct { border-left: 3px solid var(--accent-green); }
.review-item.wrong   { border-left: 3px solid var(--accent-red); }
.review-item.skipped { border-left: 3px solid var(--text-tertiary); }

.review-item-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--space-md) var(--space-lg);
  cursor: pointer;
  user-select: none;
}

.review-item-header:hover { background: rgba(255,255,255,0.03); }

.review-item-body {
  padding: 0 var(--space-lg) var(--space-lg);
  display: none;
}

.review-item-body.open { display: block; }

/* ─── Mobile Overrides ───────────────────────────────────── */
@media (max-width: 768px) {
  /* Remove backdrop-filter on mobile to fix iOS Safari white screen bug */
  .card,
  .question-card,
  .modal,
  .modal-overlay,
  .toast {
    backdrop-filter: none !important;
    -webkit-backdrop-filter: none !important;
  }

  .modal-overlay {
    background: rgba(0, 0, 0, 0.88);
  }

  .card { padding: var(--space-lg); }
  .card-sm { padding: var(--space-md); }

  .question-card { padding: var(--space-lg); border-radius: var(--radius-md); }

  .option-btn {
    padding: 14px var(--space-md);
    min-height: 52px;
    font-size: 0.93rem;
  }

  /* Scrollable filter tabs */
  .filter-tabs {
    overflow-x: auto;
    -webkit-overflow-scrolling: touch;
    width: 100%;
    scrollbar-width: none;
  }
  .filter-tabs::-webkit-scrollbar { display: none; }
  .filter-tab { white-space: nowrap; padding: 8px 14px; font-size: 0.85rem; }

  /* Answer palette: 8 cols on mobile */
  .answer-palette { grid-template-columns: repeat(8, 1fr); gap: 4px; }
  .palette-btn { font-size: 0.65rem; }

  /* Review header */
  .review-item-header { padding: var(--space-md); flex-wrap: wrap; gap: var(--space-sm); }
  .review-item-body { padding: 0 var(--space-md) var(--space-md); }

  /* Stat card */
  .stat-card { padding: var(--space-md); }
  .stat-number { font-size: clamp(1.5rem, 6vw, 2.5rem); }

  /* Modal */
  .modal { padding: var(--space-lg); }
  .modal-actions { flex-wrap: wrap; }
  .modal-actions .btn { flex: 1; justify-content: center; }
}

/* ─── Animations ─────────────────────────────────────────── */
@keyframes fadeIn {
  from { opacity: 0; }
  to   { opacity: 1; }
}

@keyframes fadeInDown {
  from { opacity: 0; transform: translateY(-10px); }
  to   { opacity: 1; transform: translateY(0); }
}

@keyframes fadeInUp {
  from { opacity: 0; transform: translateY(20px); }
  to   { opacity: 1; transform: translateY(0); }
}

@keyframes scaleIn {
  from { opacity: 0; transform: scale(0.9); }
  to   { opacity: 1; transform: scale(1); }
}

.animate-fade-in { animation: fadeIn 0.4s ease both; }
.animate-fade-up { animation: fadeInUp 0.5s ease both; }