:root {
  --bg: #f5f6f8;
  --card: #ffffff;
  --text: #202124;
  --muted: #5f6368;
  --primary: #2f5ce0;
  --primary-dark: #1f3fa6;
  --correct-bg: #e6f7ec;
  --correct-border: #34a853;
  --wrong-bg: #fdecea;
  --wrong-text: #c5221f;
  --border: #e0e2e6;
  --soft-bg: #eef2ff;
  --todo-bg: #fff4e0;
  --todo-text: #a15c00;
  --empty-bg: #eeeeee;
  --shadow-color: rgba(0, 0, 0, 0.08);
  --radius: 10px;
  --chart-1: #1f6f8b;
  --chart-2: #8fb8c8;
  --chart-3: #c46a2b;
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #0f1115;
    --card: #1a1d24;
    --text: #e4e6eb;
    --muted: #9aa0ab;
    --primary: #5b8def;
    --primary-dark: #9db8f5;
    --correct-bg: #113824;
    --correct-border: #3ddc84;
    --wrong-bg: #3a1620;
    --wrong-text: #ff6b6b;
    --border: #2c313a;
    --soft-bg: #1e2536;
    --todo-bg: #3a2e12;
    --todo-text: #e0a94a;
    --empty-bg: #23262c;
    --shadow-color: rgba(0, 0, 0, 0.45);
    --chart-1: #6cbad6;
    --chart-2: #3d6f82;
    --chart-3: #f0a86a;
  }
}

:root[data-theme="dark"] {
  --bg: #0f1115;
  --card: #1a1d24;
  --text: #e4e6eb;
  --muted: #9aa0ab;
  --primary: #5b8def;
  --primary-dark: #9db8f5;
  --correct-bg: #113824;
  --correct-border: #3ddc84;
  --wrong-bg: #3a1620;
  --wrong-text: #ff6b6b;
  --border: #2c313a;
  --soft-bg: #1e2536;
  --todo-bg: #3a2e12;
  --todo-text: #e0a94a;
  --empty-bg: #23262c;
  --shadow-color: rgba(0, 0, 0, 0.45);
  --chart-1: #6cbad6;
  --chart-2: #3d6f82;
  --chart-3: #f0a86a;
}

* { box-sizing: border-box; }

html { -webkit-text-size-adjust: 100%; }

body {
  margin: 0;
  font-family: "Segoe UI", Arial, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.5;
  transition: background 0.2s ease, color 0.2s ease;
  overflow-x: hidden;
}

img, svg, table { max-width: 100%; }

header.site-header {
  background: var(--primary);
  color: #fff;
  padding: 16px 24px;
}

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

header.site-header h1 {
  margin: 0;
  font-size: 1.4rem;
}

.theme-toggle-btn {
  flex-shrink: 0;
  border: none;
  background: rgba(255, 255, 255, 0.15);
  color: #fff;
  width: 40px;
  height: 40px;
  border-radius: 50%;
  font-size: 1.2rem;
  line-height: 1;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: background 0.15s ease;
}

.theme-toggle-btn:hover {
  background: rgba(255, 255, 255, 0.3);
}

nav.main-nav {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

nav.main-nav a {
  color: #fff;
  text-decoration: none;
  padding: 8px 14px;
  border-radius: 999px;
  background: rgba(255,255,255,0.15);
  font-size: 0.9rem;
  transition: background 0.15s ease;
  white-space: nowrap;
}

nav.main-nav a:hover {
  background: rgba(255,255,255,0.3);
}

nav.main-nav a.active {
  background: #fff;
  color: #1f3fa6;
  font-weight: 600;
}

main {
  max-width: 900px;
  margin: 0 auto;
  padding: 24px 20px 60px;
}

.hero {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px;
  margin-bottom: 24px;
}

.subject-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 16px;
}

.subject-card {
  display: block;
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 18px;
  text-decoration: none;
  color: var(--text);
  transition: box-shadow 0.15s ease, transform 0.15s ease;
}

.subject-card:hover {
  box-shadow: 0 4px 14px var(--shadow-color);
  transform: translateY(-2px);
}

.subject-card h3 {
  margin: 0 0 6px 0;
  color: var(--primary-dark);
}

.subject-card p {
  margin: 0;
  color: var(--muted);
  font-size: 0.9rem;
}

.status-badge {
  display: inline-block;
  margin-top: 10px;
  font-size: 0.75rem;
  font-weight: 600;
  padding: 3px 9px;
  border-radius: 999px;
}

.status-ready { background: var(--correct-bg); color: var(--correct-border); }
.status-todo { background: var(--todo-bg); color: var(--todo-text); }
.status-empty { background: var(--empty-bg); color: var(--muted); }

.page-title {
  margin-top: 0;
}

.question-card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px 22px;
  margin-bottom: 20px;
}

.question-number {
  font-size: 0.8rem;
  color: var(--muted);
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.03em;
}

.question-text {
  font-weight: 600;
  margin: 6px 0 14px 0;
  font-size: 1.02rem;
}

.options {
  list-style: none;
  margin: 0 0 14px 0;
  padding: 0;
}

.options li {
  padding: 8px 12px;
  border-radius: 8px;
  border: 1px solid var(--border);
  margin-bottom: 6px;
  font-size: 0.95rem;
}

.options li.correct {
  background: var(--correct-bg);
  border-color: var(--correct-border);
  font-weight: 600;
  position: relative;
}

.options li.correct::before {
  content: "✔ Correta — ";
  color: var(--correct-border);
  font-weight: 700;
}

.explanation {
  background: var(--soft-bg);
  border-left: 4px solid var(--primary);
  padding: 10px 14px;
  border-radius: 6px;
  font-size: 0.92rem;
  color: var(--text);
}

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

.fill-answer {
  background: var(--correct-bg);
  color: var(--correct-border);
  padding: 2px 9px;
  border-radius: 6px;
  font-weight: 700;
  display: inline-block;
}

.dialogue-box {
  background: var(--soft-bg);
  border-radius: 8px;
  padding: 14px 16px;
  margin: 10px 0;
  font-size: 0.95rem;
  line-height: 1.8;
}

.dialogue-box p {
  margin: 4px 0;
}

.tf-statement {
  display: flex;
  align-items: flex-start;
  gap: 12px;
  flex-wrap: wrap;
}

.tf-answer {
  flex-shrink: 0;
  font-weight: 700;
  padding: 4px 12px;
  border-radius: 999px;
  font-size: 0.85rem;
}

.tf-true {
  background: var(--correct-bg);
  color: var(--correct-border);
}

.tf-false {
  background: var(--wrong-bg);
  color: var(--wrong-text);
}

.section-divider {
  margin: 32px 0 16px 0;
  font-size: 1.1rem;
  color: var(--primary-dark);
  border-bottom: 2px solid var(--border);
  padding-bottom: 6px;
}

.empty-state {
  background: var(--card);
  border: 1px dashed var(--border);
  border-radius: var(--radius);
  padding: 32px;
  text-align: center;
  color: var(--muted);
}

footer.site-footer {
  text-align: center;
  color: var(--muted);
  font-size: 0.8rem;
  padding: 20px;
}

.quiz-toolbar {
  display: flex;
  justify-content: flex-end;
  margin-bottom: 8px;
}

.print-btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  background: var(--primary);
  color: #fff;
  border: none;
  padding: 9px 16px;
  border-radius: 8px;
  font-size: 0.9rem;
  font-weight: 600;
  cursor: pointer;
  transition: background 0.15s ease;
}

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

.topic-filter {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin: 4px 0 18px 0;
}

.topic-btn {
  border: 1px solid var(--border);
  background: var(--card);
  color: var(--muted);
  padding: 7px 14px;
  border-radius: 999px;
  font-size: 0.85rem;
  cursor: pointer;
  transition: background 0.15s ease, color 0.15s ease, border-color 0.15s ease;
}

.topic-btn:hover {
  border-color: var(--primary);
  color: var(--primary-dark);
}

.topic-btn.active {
  background: var(--primary);
  border-color: var(--primary);
  color: #fff;
  font-weight: 600;
}

.pagination {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  justify-content: center;
  margin: 24px 0 10px 0;
}

.page-btn {
  border: 1px solid var(--border);
  background: var(--card);
  color: var(--text);
  padding: 7px 12px;
  border-radius: 8px;
  font-size: 0.9rem;
  cursor: pointer;
  min-width: 38px;
}

.page-btn:hover:not(:disabled) {
  border-color: var(--primary);
  color: var(--primary-dark);
}

.page-btn.active {
  background: var(--primary);
  border-color: var(--primary);
  color: #fff;
  font-weight: 700;
}

.page-btn:disabled {
  opacity: 0.4;
  cursor: not-allowed;
}

.table-wrap {
  overflow-x: auto;
  margin: 10px 0;
  -webkit-overflow-scrolling: touch;
}

.table-wrap table {
  margin: 0;
}

.calc-table {
  width: 100%;
  border-collapse: collapse;
  margin: 10px 0;
  font-size: 0.9rem;
}

.calc-table th, .calc-table td {
  border: 1px solid var(--border);
  padding: 6px 10px;
  text-align: center;
}

.calc-table th {
  background: var(--soft-bg);
  font-weight: 600;
}

.calc-table tr.sum td {
  font-weight: 700;
  border-top: 2px solid var(--text);
}

.formula-box {
  font-family: "Courier New", monospace;
  background: var(--soft-bg);
  border-left: 4px solid var(--primary);
  padding: 10px 12px;
  margin: 10px 0;
  border-radius: 0 6px 6px 0;
  white-space: pre-wrap;
  word-break: break-word;
  font-size: 0.9rem;
  line-height: 1.6;
  overflow-x: auto;
}

.chart-svg {
  display: block;
  width: 100%;
  height: auto;
  max-width: 560px;
  margin: 14px auto;
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 8px;
}

.pie-wrap {
  display: flex;
  align-items: center;
  gap: 24px;
  flex-wrap: wrap;
  margin: 14px 0;
}

.pie-chart {
  width: 180px;
  height: 180px;
  border-radius: 50%;
  flex-shrink: 0;
  border: 1px solid var(--border);
}

.pie-legend {
  list-style: none;
  padding: 0;
  margin: 0;
  font-size: 0.85rem;
}

.pie-legend li {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-bottom: 6px;
}

.legend-swatch {
  width: 14px;
  height: 14px;
  border-radius: 3px;
  flex-shrink: 0;
  display: inline-block;
}

.back-to-top-btn {
  position: fixed;
  bottom: 24px;
  right: 24px;
  width: 46px;
  height: 46px;
  border: none;
  border-radius: 50%;
  background: var(--primary);
  color: #fff;
  font-size: 1.3rem;
  line-height: 1;
  cursor: pointer;
  display: none;
  align-items: center;
  justify-content: center;
  box-shadow: 0 4px 14px rgba(0,0,0,0.25);
  z-index: 999;
  opacity: 0;
  transition: opacity 0.2s ease, background 0.15s ease;
}

.back-to-top-btn.visible {
  display: flex;
  opacity: 1;
}

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

/* ---------- Mobile responsiveness ---------- */
@media (max-width: 640px) {
  header.site-header {
    padding: 12px 14px;
  }

  .header-top h1 {
    font-size: 1.1rem;
  }

  .theme-toggle-btn {
    width: 36px;
    height: 36px;
    font-size: 1.05rem;
  }

  nav.main-nav {
    gap: 6px;
  }

  nav.main-nav a {
    padding: 7px 11px;
    font-size: 0.82rem;
  }

  main {
    padding: 16px 14px 56px;
  }

  .hero {
    padding: 18px;
  }

  .question-card {
    padding: 16px 15px;
  }

  .question-text {
    font-size: 0.98rem;
  }

  .quiz-toolbar {
    justify-content: stretch;
  }

  .print-btn {
    width: 100%;
    justify-content: center;
    padding: 11px 16px;
  }

  .topic-filter {
    gap: 6px;
    margin: 4px 0 14px 0;
  }

  .topic-btn {
    padding: 6px 12px;
    font-size: 0.8rem;
  }

  .pagination {
    gap: 5px;
  }

  .page-btn {
    padding: 6px 10px;
    font-size: 0.85rem;
    min-width: 34px;
  }

  .back-to-top-btn {
    bottom: 16px;
    right: 16px;
    width: 42px;
    height: 42px;
    font-size: 1.1rem;
  }

  .pie-wrap {
    flex-direction: column;
    align-items: flex-start;
    gap: 14px;
  }

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

@media (max-width: 380px) {
  .header-top h1 {
    font-size: 0.98rem;
  }

  nav.main-nav a {
    padding: 6px 10px;
    font-size: 0.78rem;
  }
}

/* ---------- Estatística page (Chart.js-based question sections) ---------- */
.stats-page .question-card {
  padding: 20px 18px;
}

.stats-page .qhead {
  display: flex;
  gap: 12px;
  align-items: baseline;
  flex-wrap: wrap;
}

.stats-page .qhead h2 {
  font-family: "IBM Plex Sans Condensed", "Arial Narrow", system-ui, sans-serif;
  font-size: 1.25rem;
  margin: 0;
  color: var(--text);
}

.stats-page .qnum {
  font: 600 13px "IBM Plex Mono", monospace;
  color: #fff;
  background: var(--primary);
  padding: 2px 9px;
  border-radius: 4px;
  flex: none;
}

.stats-page h3 {
  font-family: "IBM Plex Sans Condensed", "Arial Narrow", system-ui, sans-serif;
  font-size: 1.02rem;
  color: var(--primary-dark);
  margin: 20px 0 4px 0;
}

.stats-page .enun {
  color: var(--muted);
  font-size: 0.9rem;
  margin: 8px 0 0;
}

.stats-page .slide {
  font: 12px "IBM Plex Mono", monospace;
  color: var(--muted);
  letter-spacing: 0.02em;
  display: block;
  margin: 2px 0 6px;
}

.stats-page .f {
  font-family: "IBM Plex Mono", "Courier New", monospace;
  font-size: 0.85rem;
  background: var(--soft-bg);
  border-radius: 6px;
  padding: 10px 12px;
  margin: 10px 0;
  overflow-x: auto;
  white-space: pre;
  line-height: 1.7;
  -webkit-overflow-scrolling: touch;
}

.stats-page .ans {
  background: var(--correct-bg);
  color: var(--text);
  border-left: 3px solid var(--correct-border);
  padding: 10px 12px;
  margin: 12px 0;
  border-radius: 0 6px 6px 0;
  font-size: 0.92rem;
}

.stats-page .ans b {
  color: var(--correct-border);
}

.stats-page .note {
  background: var(--todo-bg);
  color: var(--text);
  border-left: 3px solid var(--todo-text);
  padding: 8px 12px;
  margin: 12px 0;
  font-size: 0.88rem;
  border-radius: 0 6px 6px 0;
}

.stats-page .tw {
  overflow-x: auto;
  margin: 10px 0;
  -webkit-overflow-scrolling: touch;
}

.stats-page table {
  border-collapse: collapse;
  font-variant-numeric: tabular-nums;
  font-size: 0.82rem;
  min-width: 100%;
}

.stats-page th, .stats-page td {
  padding: 6px 10px;
  border-bottom: 1px solid var(--border);
  text-align: right;
  white-space: nowrap;
}

.stats-page th {
  font-weight: 600;
  color: var(--muted);
  font-size: 0.72rem;
  text-transform: uppercase;
  letter-spacing: 0.04em;
}

.stats-page th:first-child, .stats-page td:first-child {
  text-align: left;
  white-space: normal;
}

.stats-page tr.sum td {
  font-weight: 600;
  border-top: 2px solid var(--text);
}

.stats-page tr.hl td {
  background: var(--soft-bg);
}

.stats-page .stat-chart {
  position: relative;
  height: 260px;
  margin: 12px 0;
}

.stats-page svg text {
  font-family: "IBM Plex Mono", "Courier New", monospace;
}

@media (max-width: 640px) {
  .stats-page .qhead h2 {
    font-size: 1.05rem;
  }

  .stats-page .f, .stats-page table {
    font-size: 0.78rem;
  }

  .stats-page .stat-chart {
    height: 220px;
  }
}

@media print {
  .stats-page .stat-chart {
    height: 220px;
  }
}

@media print {
  :root {
    --bg: #ffffff;
    --card: #ffffff;
    --text: #1b2330;
    --muted: #5f6368;
    --primary: #2f5ce0;
    --primary-dark: #1f3fa6;
    --correct-bg: #e6f7ec;
    --correct-border: #34a853;
    --wrong-bg: #fdecea;
    --wrong-text: #c5221f;
    --border: #cccccc;
    --soft-bg: #eef2ff;
    --todo-bg: #fff4e0;
    --todo-text: #a15c00;
    --empty-bg: #eeeeee;
  }

  header.site-header,
  .quiz-toolbar,
  .topic-filter,
  .pagination,
  .back-to-top-btn,
  footer.site-footer {
    display: none !important;
  }

  body {
    background: #fff;
  }

  main {
    max-width: 100%;
    padding: 0;
  }

  .question-card {
    break-inside: avoid;
    page-break-inside: avoid;
    border: 1px solid #ccc;
    box-shadow: none;
  }

  .section-divider {
    break-after: avoid;
    page-break-after: avoid;
  }

  .calc-table, .formula-box, .chart-svg, .pie-wrap, .table-wrap {
    break-inside: avoid;
  }
}