/* ===== Reset & Variables ===== */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

:root {
  --color-primary: #1a5276;
  --color-primary-light: #2980b9;
  --color-primary-dark: #0e2f44;
  --color-correct: #27ae60;
  --color-correct-bg: #eafaf1;
  --color-incorrect: #e74c3c;
  --color-incorrect-bg: #fdedec;
  --color-warning: #f39c12;
  --color-bg: #f0f4f8;
  --color-card: #ffffff;
  --color-text: #2c3e50;
  --color-text-light: #7f8c8d;
  --color-border: #dce1e6;
  --color-hover: #eef2f7;
  --color-selected: #d4e6f1;
  --color-selected-border: #2980b9;
  --color-flag: #f39c12;
  --radius: 10px;
  --radius-sm: 6px;
  --shadow: 0 2px 8px rgba(0,0,0,0.08);
  --shadow-lg: 0 4px 16px rgba(0,0,0,0.12);
  --max-width: 800px;
  --transition: 0.2s ease;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
  background: var(--color-bg);
  color: var(--color-text);
  line-height: 1.6;
  min-height: 100vh;
}

.app {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 20px 16px;
  min-height: 100vh;
}

/* ===== Typography ===== */
h1 { font-size: 2rem; font-weight: 700; }
h2 { font-size: 1.5rem; font-weight: 600; }
h3 { font-size: 1.1rem; font-weight: 600; }

/* ===== Buttons ===== */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 12px 24px;
  border: none;
  border-radius: var(--radius-sm);
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  transition: all var(--transition);
  text-decoration: none;
}

.btn:focus-visible {
  outline: 3px solid var(--color-primary-light);
  outline-offset: 2px;
}

.btn--primary {
  background: var(--color-primary);
  color: white;
}
.btn--primary:hover {
  background: var(--color-primary-light);
}

.btn--secondary {
  background: white;
  color: var(--color-primary);
  border: 2px solid var(--color-primary);
}
.btn--secondary:hover {
  background: var(--color-hover);
}

.btn--ghost {
  background: transparent;
  color: var(--color-text-light);
  padding: 8px 16px;
}
.btn--ghost:hover {
  background: var(--color-hover);
  color: var(--color-text);
}

.btn--danger {
  background: var(--color-incorrect);
  color: white;
}
.btn--danger:hover {
  background: #c0392b;
}

.btn--small {
  padding: 8px 16px;
  font-size: 0.875rem;
}

.btn--full {
  width: 100%;
}

.btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

/* ===== Cards ===== */
.card {
  background: var(--color-card);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 24px;
}

/* ===== Home Screen ===== */
.home {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  min-height: 80vh;
  text-align: center;
  gap: 32px;
}

.home__icon {
  font-size: 4rem;
}

.home__title {
  color: var(--color-primary);
}

.home__subtitle {
  color: var(--color-text-light);
  font-size: 1.1rem;
  margin-top: 4px;
}

.home__stats {
  color: var(--color-text-light);
  font-size: 0.95rem;
}

.home__last-score {
  color: var(--color-text-light);
  font-size: 0.9rem;
}

.home__actions {
  display: flex;
  flex-direction: column;
  gap: 12px;
  width: 100%;
  max-width: 320px;
}

/* ===== Config Screen ===== */
.config {
  display: flex;
  flex-direction: column;
  gap: 24px;
}

.config__header {
  display: flex;
  align-items: center;
  gap: 12px;
}

.config__section {
  background: var(--color-card);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 20px;
}

.config__section h3 {
  margin-bottom: 12px;
  color: var(--color-primary);
}

.config__categories {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(200px, 1fr));
  gap: 8px;
}

.config__category-item {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 8px 12px;
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: background var(--transition);
}
.config__category-item:hover {
  background: var(--color-hover);
}

.config__category-item input[type="checkbox"] {
  width: 18px;
  height: 18px;
  accent-color: var(--color-primary);
}

.config__count-options {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
}

.config__count-btn {
  padding: 8px 20px;
  border: 2px solid var(--color-border);
  border-radius: var(--radius-sm);
  background: white;
  cursor: pointer;
  font-weight: 600;
  transition: all var(--transition);
}
.config__count-btn:hover {
  border-color: var(--color-primary-light);
}
.config__count-btn--active {
  background: var(--color-primary);
  color: white;
  border-color: var(--color-primary);
}

.config__toggle {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 4px 0;
}

.config__toggle input[type="checkbox"] {
  width: 18px;
  height: 18px;
  accent-color: var(--color-primary);
}

.config__section-hint {
  color: var(--color-text-light);
  font-size: 0.85rem;
  margin-bottom: 12px;
}

.config__sources {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.config__source-item {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 10px 14px;
  border: 2px solid var(--color-border);
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: all var(--transition);
}

.config__source-item:hover {
  border-color: var(--color-primary-light);
  background: var(--color-hover);
}

.config__source-item:has(input:checked) {
  border-color: var(--color-selected-border);
  background: var(--color-selected);
}

.config__source-item input[type="checkbox"] {
  width: 18px;
  height: 18px;
  accent-color: var(--color-primary);
}

.config__source-label {
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.config__source-label strong {
  font-size: 0.95rem;
}

.config__source-label small {
  color: var(--color-text-light);
  font-size: 0.8rem;
}

.config__select-all {
  display: flex;
  gap: 8px;
  margin-top: 8px;
}

.config__summary {
  text-align: center;
  padding: 12px;
  background: var(--color-selected);
  border-radius: var(--radius-sm);
  color: var(--color-primary);
  font-size: 0.95rem;
}

.config__actions {
  display: flex;
  gap: 12px;
}

/* ===== Quiz Screen ===== */
.quiz {
  display: flex;
  flex-direction: column;
  gap: 20px;
}

.quiz__header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 12px;
}

.quiz__progress-text {
  font-weight: 600;
  color: var(--color-primary);
}

.quiz__header-actions {
  display: flex;
  gap: 8px;
  align-items: center;
}

.quiz__timer {
  font-weight: 700;
  font-size: 1.1rem;
  color: var(--color-primary);
  font-variant-numeric: tabular-nums;
}

.quiz__timer--warning {
  color: var(--color-warning);
}

.quiz__timer--danger {
  color: var(--color-incorrect);
}

/* ===== Progress Bar ===== */
.progress-bar {
  width: 100%;
  height: 8px;
  background: var(--color-border);
  border-radius: 4px;
  overflow: hidden;
}

.progress-bar__fill {
  height: 100%;
  background: var(--color-primary);
  border-radius: 4px;
  transition: width 0.3s ease;
}

/* ===== Question Card ===== */
.question-card {
  background: var(--color-card);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 28px;
}

.question-card__type-badge {
  display: inline-block;
  padding: 3px 10px;
  border-radius: 12px;
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.5px;
  margin-bottom: 12px;
}

.question-card__type-badge--single {
  background: #ebf5fb;
  color: var(--color-primary);
}

.question-card__type-badge--multiple {
  background: #fef9e7;
  color: #8e6e00;
}

.question-card__stem {
  font-size: 1.1rem;
  line-height: 1.7;
  margin-bottom: 20px;
}

.question-card__options {
  display: flex;
  flex-direction: column;
  gap: 10px;
  list-style: none;
}

.question-card__option {
  display: flex;
  align-items: flex-start;
  gap: 12px;
  padding: 14px 16px;
  border: 2px solid var(--color-border);
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: all var(--transition);
  user-select: none;
}

.question-card__option:hover {
  border-color: var(--color-primary-light);
  background: var(--color-hover);
}

.question-card__option--selected {
  border-color: var(--color-selected-border);
  background: var(--color-selected);
}

.question-card__option--correct {
  border-color: var(--color-correct);
  background: var(--color-correct-bg);
}

.question-card__option--incorrect {
  border-color: var(--color-incorrect);
  background: var(--color-incorrect-bg);
}

.question-card__option--disabled {
  cursor: default;
  pointer-events: none;
}

.question-card__option-key {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 28px;
  height: 28px;
  min-width: 28px;
  border-radius: 50%;
  background: var(--color-bg);
  font-weight: 700;
  font-size: 0.85rem;
  color: var(--color-text-light);
}

.question-card__option--selected .question-card__option-key {
  background: var(--color-primary);
  color: white;
}

.question-card__option--correct .question-card__option-key {
  background: var(--color-correct);
  color: white;
}

.question-card__option--incorrect .question-card__option-key {
  background: var(--color-incorrect);
  color: white;
}

.question-card__option-text {
  flex: 1;
  padding-top: 2px;
}

.question-card__explanation {
  margin-top: 20px;
  padding: 16px;
  background: #f8f9fa;
  border-left: 4px solid var(--color-primary);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
}

.question-card__explanation h4 {
  color: var(--color-primary);
  margin-bottom: 8px;
}

.question-card__explanation p {
  color: var(--color-text);
  line-height: 1.7;
}

.question-card__source {
  margin-top: 8px;
  font-size: 0.8rem;
  color: var(--color-text-light);
  font-style: italic;
}

/* ===== Quiz Navigation ===== */
.quiz__nav {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 12px;
}

.quiz__nav-center {
  font-size: 0.9rem;
  color: var(--color-text-light);
}

/* ===== Question Navigator Grid ===== */
.quiz__navigator {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  justify-content: center;
  padding: 16px;
  background: var(--color-card);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
}

.quiz__nav-dot {
  width: 36px;
  height: 36px;
  display: flex;
  align-items: center;
  justify-content: center;
  border: 2px solid var(--color-border);
  border-radius: var(--radius-sm);
  font-size: 0.8rem;
  font-weight: 600;
  cursor: pointer;
  transition: all var(--transition);
  background: white;
}

.quiz__nav-dot:hover {
  border-color: var(--color-primary-light);
}

.quiz__nav-dot--current {
  border-color: var(--color-primary);
  background: var(--color-primary);
  color: white;
}

.quiz__nav-dot--answered {
  border-color: var(--color-primary-light);
  background: var(--color-selected);
  color: var(--color-primary);
}

.quiz__nav-dot--flagged {
  border-color: var(--color-flag);
  background: #fef9e7;
}

.quiz__nav-dot--flagged::after {
  content: '';
  position: absolute;
  top: -2px;
  right: -2px;
  width: 8px;
  height: 8px;
  background: var(--color-flag);
  border-radius: 50%;
}

.quiz__nav-dot {
  position: relative;
}

.quiz__nav-arrow {
  width: 36px;
  height: 36px;
  display: flex;
  align-items: center;
  justify-content: center;
  border: 2px solid var(--color-border);
  border-radius: var(--radius-sm);
  font-size: 1rem;
  font-weight: 700;
  cursor: pointer;
  transition: all var(--transition);
  background: white;
  color: var(--color-primary);
}

.quiz__nav-arrow:hover {
  background: var(--color-primary);
  color: white;
  border-color: var(--color-primary);
}

/* ===== Results Screen ===== */
.results {
  display: flex;
  flex-direction: column;
  gap: 24px;
}

.results__score-card {
  background: var(--color-card);
  border-radius: var(--radius);
  box-shadow: var(--shadow-lg);
  padding: 40px;
  text-align: center;
}

.results__percentage {
  font-size: 4rem;
  font-weight: 800;
  color: var(--color-primary);
}

.results__percentage--pass {
  color: var(--color-correct);
}

.results__percentage--fail {
  color: var(--color-incorrect);
}

.results__summary {
  margin-top: 12px;
  color: var(--color-text-light);
  font-size: 1.1rem;
}

.results__details {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 12px;
  margin-top: 24px;
}

.results__detail-item {
  padding: 16px;
  border-radius: var(--radius-sm);
  text-align: center;
}

.results__detail-item--correct {
  background: var(--color-correct-bg);
  color: var(--color-correct);
}

.results__detail-item--incorrect {
  background: var(--color-incorrect-bg);
  color: var(--color-incorrect);
}

.results__detail-item--unanswered {
  background: #f5f5f5;
  color: var(--color-text-light);
}

.results__detail-number {
  font-size: 2rem;
  font-weight: 700;
}

.results__detail-label {
  font-size: 0.85rem;
  font-weight: 600;
  margin-top: 4px;
}

.results__category-breakdown {
  background: var(--color-card);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 24px;
}

.results__category-breakdown h3 {
  margin-bottom: 16px;
  color: var(--color-primary);
}

.results__category-item {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 10px 0;
  border-bottom: 1px solid var(--color-border);
}

.results__category-item:last-child {
  border-bottom: none;
}

.results__category-name {
  flex: 0 0 180px;
  font-weight: 600;
  font-size: 0.9rem;
}

.results__category-bar {
  flex: 1;
  height: 24px;
  background: var(--color-border);
  border-radius: 12px;
  overflow: hidden;
}

.results__category-bar-fill {
  height: 100%;
  border-radius: 12px;
  transition: width 0.5s ease;
}

.results__category-bar-fill--pass {
  background: var(--color-correct);
}

.results__category-bar-fill--fail {
  background: var(--color-incorrect);
}

.results__category-score {
  flex: 0 0 70px;
  text-align: right;
  font-weight: 600;
  font-size: 0.9rem;
}

.results__actions {
  display: flex;
  gap: 12px;
  justify-content: center;
  flex-wrap: wrap;
}

/* ===== Review Screen ===== */
.review {
  display: flex;
  flex-direction: column;
  gap: 20px;
}

.review__header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 12px;
}

.review__filters {
  display: flex;
  gap: 6px;
}

.review__filter-btn {
  padding: 6px 14px;
  border: 2px solid var(--color-border);
  border-radius: var(--radius-sm);
  background: white;
  cursor: pointer;
  font-size: 0.85rem;
  font-weight: 600;
  transition: all var(--transition);
}

.review__filter-btn:hover {
  border-color: var(--color-primary-light);
}

.review__filter-btn--active {
  background: var(--color-primary);
  color: white;
  border-color: var(--color-primary);
}

.review__nav {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.review__result-badge {
  display: inline-block;
  padding: 4px 12px;
  border-radius: 12px;
  font-size: 0.85rem;
  font-weight: 700;
  margin-bottom: 12px;
}

.review__result-badge--correct {
  background: var(--color-correct-bg);
  color: var(--color-correct);
}

.review__result-badge--incorrect {
  background: var(--color-incorrect-bg);
  color: var(--color-incorrect);
}

.review__result-badge--unanswered {
  background: #f5f5f5;
  color: var(--color-text-light);
}

/* ===== Modal ===== */
.modal-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.5);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 100;
  padding: 20px;
}

.modal {
  background: var(--color-card);
  border-radius: var(--radius);
  box-shadow: var(--shadow-lg);
  padding: 32px;
  max-width: 440px;
  width: 100%;
  text-align: center;
}

.modal h3 {
  margin-bottom: 12px;
}

.modal p {
  color: var(--color-text-light);
  margin-bottom: 24px;
}

.modal__actions {
  display: flex;
  gap: 12px;
  justify-content: center;
}

/* ===== Error ===== */
.error {
  text-align: center;
  padding: 60px 20px;
}

.error h2 {
  color: var(--color-incorrect);
  margin-bottom: 12px;
}

.error code {
  display: inline-block;
  margin-top: 12px;
  padding: 8px 16px;
  background: #2c3e50;
  color: #ecf0f1;
  border-radius: var(--radius-sm);
  font-size: 0.9rem;
}

/* ===== History Screen ===== */
.history {
  display: flex;
  flex-direction: column;
  gap: 20px;
}

.history__header {
  display: flex;
  align-items: center;
  gap: 12px;
}

.history__stats {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 12px;
}

.history__stat {
  background: var(--color-card);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 16px;
  text-align: center;
}

.history__stat-number {
  font-size: 1.5rem;
  font-weight: 800;
  color: var(--color-primary);
}

.history__stat-label {
  font-size: 0.8rem;
  color: var(--color-text-light);
  font-weight: 600;
  margin-top: 4px;
}

.history__list {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.history__item {
  background: var(--color-card);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 16px 20px;
}

.history__item-main {
  display: flex;
  align-items: center;
  gap: 16px;
}

.history__pct {
  font-size: 1.4rem;
  font-weight: 800;
  min-width: 60px;
  text-align: center;
}

.history__pct--pass {
  color: var(--color-correct);
}

.history__pct--fail {
  color: var(--color-incorrect);
}

.history__item-details {
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.history__item-score {
  font-weight: 600;
  font-size: 0.95rem;
}

.history__item-meta {
  font-size: 0.8rem;
  color: var(--color-text-light);
}

.history__item-sources {
  font-size: 0.75rem;
  color: var(--color-text-light);
  font-style: italic;
}

.history__item-cats {
  display: flex;
  flex-wrap: wrap;
  gap: 4px;
  margin-top: 10px;
}

.history__cat-badge {
  font-size: 0.7rem;
  padding: 2px 8px;
  border-radius: 10px;
  background: var(--color-correct-bg);
  color: var(--color-correct);
  font-weight: 600;
}

.history__cat-badge--fail {
  background: var(--color-incorrect-bg);
  color: var(--color-incorrect);
}

/* ===== Responsive ===== */
@media (max-width: 600px) {
  h1 { font-size: 1.5rem; }
  h2 { font-size: 1.25rem; }

  .question-card { padding: 20px; }
  .question-card__stem { font-size: 1rem; }
  .question-card__option { padding: 12px; }

  .results__details { grid-template-columns: repeat(3, 1fr); gap: 8px; }
  .results__detail-number { font-size: 1.5rem; }
  .results__category-name { flex: 0 0 120px; font-size: 0.8rem; }
  .results__score-card { padding: 24px; }
  .results__percentage { font-size: 3rem; }

  .config__categories { grid-template-columns: 1fr; }

  .quiz__nav-dot { width: 32px; height: 32px; font-size: 0.75rem; }

  .history__stats { grid-template-columns: repeat(2, 1fr); }
  .history__stat-number { font-size: 1.2rem; }
  .history__pct { font-size: 1.1rem; min-width: 48px; }
}