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

:root {
  --primary: #1a56db;
  --primary-dark: #1e40af;
  --primary-light: #3b82f6;
  --success: #16a34a;
  --success-light: #dcfce7;
  --danger: #dc2626;
  --danger-light: #fee2e2;
  --warning: #f59e0b;
  --warning-light: #fef3c7;
  --bg: #f1f5f9;
  --card-bg: #ffffff;
  --text: #1e293b;
  --text-muted: #64748b;
  --border: #e2e8f0;
  --shadow: 0 1px 3px rgba(0,0,0,0.08), 0 1px 2px rgba(0,0,0,0.06);
  --shadow-lg: 0 10px 30px rgba(0,0,0,0.1);
  --radius: 12px;
  --radius-sm: 8px;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  min-height: 100vh;
  overflow-y: scroll;
}

/* ===== Header ===== */
.app-header {
  background: var(--card-bg);
  border-bottom: 1px solid var(--border);
  box-shadow: var(--shadow);
  position: sticky;
  top: 0;
  z-index: 100;
}

.header-content {
  max-width: 900px;
  margin: 0 auto;
  padding: 12px 20px;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.logo {
  display: flex;
  align-items: center;
  gap: 10px;
  cursor: pointer;
}

.logo-icon {
  font-size: 28px;
}

.logo-text {
  display: flex;
  flex-direction: column;
}

.logo-title {
  font-weight: 700;
  font-size: 18px;
  color: var(--text);
}

.logo-subtitle {
  font-size: 12px;
  color: var(--text-muted);
}

.test-status-bar {
  display: flex;
  align-items: center;
  gap: 20px;
  background: var(--card-bg);
  border-radius: var(--radius);
  padding: 12px 20px;
  box-shadow: var(--shadow);
}

.timer-display {
  display: flex;
  align-items: center;
  gap: 6px;
  font-size: 20px;
  font-weight: 700;
  padding: 6px 14px;
  background: var(--bg);
  border-radius: var(--radius-sm);
  white-space: nowrap;
}

.timer-display.warning {
  color: var(--warning);
  background: var(--warning-light);
}

.timer-display.danger {
  color: var(--danger);
  background: var(--danger-light);
  animation: pulse 1s infinite;
}

@keyframes pulse {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.7; }
}

.progress-display {
  display: flex;
  flex-direction: column;
  gap: 4px;
  flex: 1;
  min-width: 0;
}

.progress-text {
  font-size: 13px;
  color: var(--text-muted);
  white-space: nowrap;
}

.progress-bar-container {
  height: 6px;
  background: var(--border);
  border-radius: 3px;
  overflow: hidden;
}

.progress-bar {
  height: 100%;
  background: var(--primary);
  border-radius: 3px;
  transition: width 0.3s ease;
}

/* ===== Main ===== */
.app-main {
  max-width: 900px;
  margin: 0 auto;
  padding: 24px 20px;
}

/* ===== Screens ===== */
.screen {
  display: none;
}

.screen.active {
  display: block;
}

/* ===== Home ===== */
.home-container {
  display: flex;
  flex-direction: column;
  gap: 32px;
}

.hero {
  text-align: center;
  padding: 20px 0;
}

.hero h1 {
  font-size: 28px;
  font-weight: 700;
  color: var(--text);
  margin-bottom: 8px;
}

.hero-subtitle {
  font-size: 16px;
  color: var(--text-muted);
}

.info-cards {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 16px;
}

.info-card {
  background: var(--card-bg);
  border-radius: var(--radius);
  padding: 20px;
  text-align: center;
  box-shadow: var(--shadow);
}

.info-card-icon {
  font-size: 28px;
  margin-bottom: 8px;
}

.info-card-value {
  font-size: 24px;
  font-weight: 700;
  color: var(--primary);
}

.info-card-label {
  font-size: 13px;
  color: var(--text-muted);
  margin-top: 4px;
}

.action-cards {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 16px;
}

.action-card {
  background: var(--card-bg);
  border-radius: var(--radius);
  padding: 24px;
  box-shadow: var(--shadow);
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  cursor: pointer;
  transition: transform 0.2s, box-shadow 0.2s;
}

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

.action-card.primary {
  border: 2px solid var(--primary);
}

.action-card-icon {
  font-size: 36px;
  margin-bottom: 12px;
}

.action-card h2 {
  font-size: 18px;
  margin-bottom: 8px;
}

.action-card p {
  font-size: 14px;
  color: var(--text-muted);
  margin-bottom: 16px;
  flex-grow: 1;
}

/* ===== Buttons ===== */
.btn {
  display: inline-block;
  padding: 10px 16px;
  border: none;
  border-radius: var(--radius-sm);
  font-size: 15px;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.15s;
  font-family: inherit;
}

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

.btn-primary:hover {
  background: var(--primary-dark);
}

.btn-secondary {
  background: var(--bg);
  color: var(--text);
  border: 1px solid var(--border);
}

.btn-secondary:hover {
  background: var(--border);
}

.btn-outline {
  background: transparent;
  color: var(--primary);
  border: 1px solid var(--primary);
}

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

.btn-warning {
  background: var(--warning);
  color: white;
}

.btn-warning:hover {
  background: #d97706;
}

.btn-teal {
  background: #0d9488;
  color: white;
}

.btn-teal:hover {
  background: #0f766e;
}

.btn-magenta {
  background: #c026d3;
  color: white;
}

.btn-magenta:hover {
  background: #a21caf;
}

.btn-danger {
  background: var(--danger);
  color: white;
}

.btn-danger:hover {
  background: #b91c1c;
}

.btn-success {
  background: var(--success);
  color: white;
}

.btn-success:hover {
  background: #15803d;
}

.btn-small {
  padding: 6px 14px;
  font-size: 13px;
}

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

/* ===== Topics Overview ===== */
.topics-overview {
  background: var(--card-bg);
  border-radius: var(--radius);
  padding: 24px;
  box-shadow: var(--shadow);
}

.topics-overview h3 {
  margin-bottom: 8px;
}

.topics-intro {
  font-size: 14px;
  color: var(--text-muted);
  margin-bottom: 16px;
}

.topics-list {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 8px;
}

.topic-item {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 10px 14px;
  background: var(--bg);
  border-radius: var(--radius-sm);
  font-size: 14px;
  cursor: pointer;
  transition: background 0.15s, border-color 0.15s;
  border: 2px solid transparent;
}

.topic-item:hover {
  background: #eff6ff;
  border-color: var(--primary-light);
}

.topic-item-name {
  font-weight: 500;
  min-width: 0;
}

.topic-item-count {
  display: flex;
  gap: 12px;
  align-items: center;
  font-size: 13px;
  color: var(--text-muted);
  flex-shrink: 0;
}

.topic-item-count .bank-count {
  color: var(--primary);
  font-weight: 600;
}

.topic-item-count .test-count {
  white-space: nowrap;
}

/* ===== Test Screen ===== */
.test-container {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

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

.test-header-right {
  display: flex;
  gap: 6px;
}

.question-nav {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  justify-content: center;
  background: var(--card-bg);
  padding: 12px;
  border-radius: var(--radius);
  box-shadow: var(--shadow);
}

.qnav-item {
  width: 36px;
  height: 36px;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 6px;
  font-size: 13px;
  font-weight: 600;
  cursor: pointer;
  background: var(--bg);
  color: var(--text-muted);
  border: 2px solid transparent;
  transition: all 0.15s;
}

.qnav-item:hover {
  border-color: var(--primary);
}

.qnav-item.answered {
  background: var(--primary);
  color: white;
}

.qnav-item.current {
  border-color: var(--primary-dark);
  transform: scale(1.1);
}

.qnav-item.flagged {
  border-color: var(--warning);
}

.qnav-item.flagged.current {
  border-color: var(--warning);
}

.question-card {
  background: var(--card-bg);
  border-radius: var(--radius);
  padding: 28px;
  box-shadow: var(--shadow);
}

.question-number {
  display: flex;
  align-items: center;
  gap: 4px;
  font-size: 28px;
  font-weight: 700;
  color: var(--primary);
  margin-bottom: 8px;
}

.question-of {
  font-size: 16px;
  color: var(--text-muted);
  font-weight: 400;
}

.flag-indicator {
  font-size: 18px;
  margin-left: 8px;
}

.question-section-tag {
  display: inline-block;
  padding: 4px 12px;
  background: var(--bg);
  border-radius: 20px;
  font-size: 12px;
  font-weight: 600;
  color: var(--text-muted);
  margin-bottom: 16px;
}

.question-text {
  font-size: 18px;
  font-weight: 500;
  margin-bottom: 24px;
  line-height: 1.5;
}

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

.option-item {
  display: flex;
  align-items: flex-start;
  gap: 12px;
  padding: 14px 16px;
  background: var(--bg);
  border: 2px solid transparent;
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: all 0.15s;
}

.option-item:hover {
  border-color: var(--primary-light);
  background: #eff6ff;
}

.option-item.selected {
  border-color: var(--primary);
  background: #dbeafe;
}

.option-letter {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 32px;
  height: 32px;
  min-width: 32px;
  border-radius: 50%;
  background: var(--card-bg);
  border: 2px solid var(--border);
  font-weight: 700;
  font-size: 14px;
}

.option-item.selected .option-letter {
  background: var(--primary);
  color: white;
  border-color: var(--primary);
}

.option-item.revealed {
  border-color: #c026d3;
  background: #fae8ff;
}

.option-item.revealed .option-letter {
  background: #c026d3;
  color: white;
  border-color: #c026d3;
}

.option-text {
  font-size: 15px;
  padding-top: 4px;
}

.test-nav-row {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 12px;
}

/* ===== Review Screen ===== */
.review-container {
  background: var(--card-bg);
  border-radius: var(--radius);
  padding: 28px;
  box-shadow: var(--shadow);
}

.review-container h2 {
  margin-bottom: 8px;
}

.review-intro {
  color: var(--text-muted);
  font-size: 14px;
  margin-bottom: 20px;
}

.review-grid {
  display: grid;
  grid-template-columns: repeat(10, 1fr);
  gap: 8px;
  margin-bottom: 24px;
}

.review-item {
  aspect-ratio: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 6px;
  font-size: 14px;
  font-weight: 600;
  cursor: pointer;
  background: var(--bg);
  color: var(--text-muted);
  border: 2px solid transparent;
  position: relative;
}

.review-item.answered {
  background: var(--primary);
  color: white;
}

.review-item.flagged::after {
  content: '🚩';
  position: absolute;
  top: -4px;
  right: -4px;
  font-size: 10px;
}

.review-item:hover {
  border-color: var(--primary-dark);
}

.review-footer {
  display: flex;
  justify-content: space-between;
}

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

.result-banner {
  background: var(--card-bg);
  border-radius: var(--radius);
  padding: 40px;
  text-align: center;
  box-shadow: var(--shadow);
}

.result-banner.pass {
  border-top: 4px solid var(--success);
}

.result-banner.fail {
  border-top: 4px solid var(--danger);
}

.result-icon {
  font-size: 56px;
  margin-bottom: 12px;
}

.result-title {
  font-size: 28px;
  margin-bottom: 8px;
}

.result-score {
  font-size: 36px;
  font-weight: 700;
  color: var(--primary);
  margin-bottom: 4px;
}

.result-percentage {
  font-size: 16px;
  color: var(--text-muted);
}

.result-stats {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 16px;
}

.stat-card {
  background: var(--card-bg);
  border-radius: var(--radius);
  padding: 20px;
  text-align: center;
  box-shadow: var(--shadow);
}

.stat-value {
  font-size: 28px;
  font-weight: 700;
}

.stat-card:nth-child(1) .stat-value { color: var(--success); }
.stat-card:nth-child(2) .stat-value { color: var(--danger); }
.stat-card:nth-child(3) .stat-value { color: var(--text-muted); }
.stat-card:nth-child(4) .stat-value { color: var(--primary); }

.stat-label {
  font-size: 13px;
  color: var(--text-muted);
  margin-top: 4px;
}

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

.results-breakdown, .results-review {
  background: var(--card-bg);
  border-radius: var(--radius);
  padding: 24px;
  box-shadow: var(--shadow);
}

.results-breakdown h3, .results-review h3 {
  margin-bottom: 16px;
}

.review-hint {
  font-size: 14px;
  color: var(--text-muted);
  margin-bottom: 16px;
}

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

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

.topic-breakdown-name {
  flex: 0 0 250px;
  font-size: 14px;
  font-weight: 500;
}

.topic-breakdown-bar-container {
  flex: 1;
  height: 24px;
  background: var(--bg);
  border-radius: 12px;
  overflow: hidden;
  position: relative;
}

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

.topic-breakdown-bar.correct {
  background: var(--success);
}

.topic-breakdown-bar.incorrect {
  background: var(--danger);
}

.topic-breakdown-score {
  flex: 0 0 60px;
  text-align: right;
  font-size: 14px;
  font-weight: 600;
}

/* ===== Detailed Review ===== */
.detailed-review-item {
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 20px;
  margin-bottom: 16px;
}

.detailed-review-item.correct {
  border-left: 4px solid var(--success);
}

.detailed-review-item.incorrect {
  border-left: 4px solid var(--danger);
}

.detailed-review-item.unanswered {
  border-left: 4px solid var(--text-muted);
}

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

.dr-number {
  font-weight: 700;
  color: var(--primary);
}

.dr-status {
  font-size: 13px;
  font-weight: 600;
  padding: 2px 10px;
  border-radius: 12px;
}

.dr-status.correct {
  background: var(--success-light);
  color: var(--success);
}

.dr-status.incorrect {
  background: var(--danger-light);
  color: var(--danger);
}

.dr-status.unanswered {
  background: var(--bg);
  color: var(--text-muted);
}

.dr-question {
  font-size: 16px;
  font-weight: 500;
  margin-bottom: 12px;
}

.dr-options {
  display: flex;
  flex-direction: column;
  gap: 6px;
  margin-bottom: 12px;
}

.dr-option {
  display: flex;
  align-items: flex-start;
  gap: 8px;
  padding: 8px 12px;
  border-radius: 6px;
  font-size: 14px;
}

.dr-option.correct-answer {
  background: var(--success-light);
  font-weight: 600;
}

.dr-option.user-correct {
  background: var(--success-light);
}

.dr-option.user-incorrect {
  background: var(--danger-light);
}

.dr-option-letter {
  font-weight: 700;
  min-width: 20px;
}

.dr-explanation {
  background: var(--bg);
  padding: 12px;
  border-radius: 6px;
  font-size: 14px;
  color: var(--text-muted);
}

.dr-explanation-label {
  font-weight: 600;
  color: var(--text);
}

/* ===== Practice Screen ===== */
.practice-container {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

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

.practice-topics {
  background: var(--card-bg);
  border-radius: var(--radius);
  padding: 24px;
  box-shadow: var(--shadow);
}

.practice-topics h2 {
  margin-bottom: 16px;
}

.practice-topics-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 12px;
}

.practice-topic-card {
  padding: 20px;
  background: var(--bg);
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: all 0.15s;
  border: 2px solid transparent;
}

.practice-topic-card:hover {
  border-color: var(--primary);
  background: #eff6ff;
}

.practice-topic-name {
  font-size: 16px;
  font-weight: 600;
  margin-bottom: 4px;
}

.practice-topic-meta {
  font-size: 13px;
  color: var(--text-muted);
}

.practice-content {
  background: var(--card-bg);
  border-radius: var(--radius);
  padding: 24px;
  box-shadow: var(--shadow);
}

.practice-content-header {
  display: flex;
  flex-direction: column;
  gap: 4px;
  margin-bottom: 20px;
}

.practice-content-header h3 {
  margin: 0;
}

.practice-count {
  font-size: 14px;
  color: var(--text-muted);
  margin: 0;
}

.practice-questions {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.practice-question {
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 20px;
}

.practice-q-header {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-bottom: 8px;
}

.practice-q-number {
  font-weight: 700;
  color: var(--primary);
  font-size: 14px;
}

.practice-q-text {
  font-size: 16px;
  font-weight: 500;
  margin-bottom: 14px;
}

.practice-q-options {
  display: flex;
  flex-direction: column;
  gap: 6px;
  margin-bottom: 12px;
}

.practice-q-option {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 8px 12px;
  border-radius: 6px;
  font-size: 14px;
  background: var(--bg);
}

.practice-q-option.correct {
  background: var(--success-light);
  font-weight: 600;
}

.practice-q-option-letter {
  font-weight: 700;
  min-width: 20px;
}

.practice-q-option-text {
  flex: 1;
}

.practice-q-check {
  color: var(--success);
  font-weight: 700;
  font-size: 16px;
}

.practice-q-explanation {
  background: #eff6ff;
  padding: 10px 14px;
  border-radius: 6px;
  font-size: 14px;
  color: var(--text);
}

.practice-q-explanation strong {
  color: var(--primary);
}

/* ===== Modal ===== */
.modal-overlay {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: rgba(0,0,0,0.5);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 1000;
}

.modal {
  background: var(--card-bg);
  border-radius: var(--radius);
  padding: 28px;
  max-width: 400px;
  width: 90%;
  box-shadow: var(--shadow-lg);
}

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

.modal p {
  color: var(--text-muted);
  margin-bottom: 20px;
}

.modal-actions {
  display: flex;
  gap: 12px;
  justify-content: flex-end;
}

/* ===== Utility ===== */
.hidden {
  display: none !important;
}

/* ===== Responsive ===== */
@media (max-width: 768px) {
  .info-cards {
    grid-template-columns: repeat(2, 1fr);
  }

  .action-cards {
    grid-template-columns: 1fr;
  }

  .topics-list {
    grid-template-columns: 1fr;
  }

  .topic-item-count {
    gap: 6px;
  }

  .result-stats {
    grid-template-columns: repeat(2, 1fr);
  }

  .review-grid {
    grid-template-columns: repeat(8, 1fr);
  }

  .practice-topics-grid {
    grid-template-columns: 1fr;
  }

  .topic-breakdown-name {
    flex: 0 0 150px;
  }

  .question-nav {
    gap: 4px;
  }

  .qnav-item {
    width: 30px;
    height: 30px;
    font-size: 12px;
  }

  .header-content {
    gap: 8px;
  }

  .btn {
    padding: 8px 12px;
    font-size: 14px;
  }

  .test-header-right {
    gap: 4px;
  }

  .test-status-bar {
    flex-direction: column;
    gap: 10px;
    align-items: stretch;
  }
}