:root {
  --bg: #f4f7fb;
  --card: #ffffff;
  --text: #142033;
  --muted: #5b6880;
  --border: #d8e0ee;
  --primary: #1e4ed8;
  --primary-soft: #dbe8ff;
  --secondary: #eef3fb;
  --danger: #c0392b;
  --danger-soft: #ffe9e5;
  --success-soft: #e6f7ee;
  --warning-soft: #fff4da;
  --shadow: 0 16px 32px rgba(18, 32, 51, 0.08);
  --radius: 16px;
  --radius-small: 10px;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  background: linear-gradient(180deg, #f8fbff 0%, #f3f7fb 100%);
  color: var(--text);
}

.home-link {
  display: inline-flex;
  align-items: center;
  min-height: 2.75rem;
  margin-bottom: 1rem;
  padding: 0.65rem 1rem;
  border: 1px solid var(--border);
  border-radius: 999px;
  background: rgba(255, 255, 255, 0.88);
  box-shadow: 0 12px 24px rgba(18, 32, 51, 0.06);
  color: var(--text);
  font-weight: 700;
  text-decoration: none;
  transition: transform 0.12s ease, border-color 0.12s ease, background 0.12s ease;
}

.home-link:hover,
.home-link:focus-visible {
  transform: translateY(-1px);
  border-color: #b9caf0;
  background: #ffffff;
}

code {
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  background: #f3f6fb;
  padding: 0.1rem 0.3rem;
  border-radius: 6px;
}

.page-shell {
  width: min(1440px, calc(100% - 32px));
  margin: 24px auto 48px;
}

.site-header {
  display: flex;
  justify-content: space-between;
  gap: 16px;
  align-items: flex-start;
  margin-bottom: 18px;
}

.site-header h1 {
  margin: 0 0 8px;
  font-size: clamp(1.8rem, 3vw, 2.6rem);
}

.subhead {
  margin: 0;
  color: var(--muted);
}

.header-badges {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
}

.badge {
  display: inline-flex;
  align-items: center;
  border: 1px solid var(--border);
  background: var(--card);
  border-radius: 999px;
  padding: 0.45rem 0.8rem;
  font-size: 0.88rem;
  font-weight: 600;
}

.subtle-badge {
  background: #f6f9ff;
  border-color: #d7e5ff;
}

.card,
.panel {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
}

.card {
  padding: 20px;
}

.panel {
  padding: 16px;
}

.screen {
  display: none;
}

.screen.active {
  display: block;
}

.centered {
  text-align: center;
  padding: 48px 20px;
}

.home-grid,
.quiz-layout,
.results-grid {
  display: grid;
  gap: 18px;
}

.home-grid {
  grid-template-columns: minmax(0, 1.5fr) minmax(320px, 0.9fr);
}

.quiz-layout {
  grid-template-columns: minmax(0, 1.45fr) minmax(280px, 0.65fr);
  align-items: start;
}

.results-grid {
  grid-template-columns: repeat(2, minmax(0, 1fr));
}

.home-main,
.home-side {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

h2, h3 {
  margin-top: 0;
}

.muted {
  color: var(--muted);
}

.tiny {
  font-size: 0.85rem;
}

.strongish {
  font-weight: 700;
  font-size: 1.05rem;
}

.inline-options {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

.chip-option {
  position: relative;
}

.chip-option input {
  position: absolute;
  opacity: 0;
  pointer-events: none;
}

.chip-option span {
  display: inline-flex;
  align-items: center;
  padding: 0.7rem 1rem;
  border-radius: 999px;
  border: 1px solid var(--border);
  background: #f8fbff;
  cursor: pointer;
  font-weight: 600;
}

.chip-option input:checked + span {
  background: var(--primary-soft);
  border-color: #9ebeff;
  color: #143a9b;
}

.custom-count-row {
  display: grid;
  grid-template-columns: 1fr 120px;
  gap: 12px;
  align-items: center;
  margin-top: 12px;
}

.custom-count-row input {
  width: 100%;
}

input[type="number"] {
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 0.75rem;
  font: inherit;
  background: #fff;
}

.topic-list {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 10px;
}

.topic-item {
  display: flex;
  align-items: flex-start;
  gap: 10px;
  padding: 10px 12px;
  border-radius: 12px;
  border: 1px solid var(--border);
  background: #fafcff;
}

.topic-item input {
  margin-top: 4px;
}

.topic-item .topic-meta {
  display: flex;
  flex-direction: column;
  gap: 3px;
}

.topic-item .topic-count {
  color: var(--muted);
  font-size: 0.82rem;
}

.panel-topline {
  display: flex;
  justify-content: space-between;
  gap: 10px;
  align-items: center;
  margin-bottom: 12px;
}

.toggle-row {
  display: flex;
  gap: 10px;
  align-items: center;
  padding: 8px 0;
}

.compact-toggle {
  padding: 0;
}

.action-row,
.nav-row,
.result-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

button {
  font: inherit;
  border: 1px solid transparent;
  border-radius: 12px;
  cursor: pointer;
  padding: 0.8rem 1rem;
  font-weight: 700;
  transition: transform 0.04s ease, opacity 0.15s ease, background 0.15s ease;
}

button:hover {
  opacity: 0.95;
}

button:active {
  transform: translateY(1px);
}

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

.secondary-button {
  background: var(--secondary);
  color: var(--text);
  border-color: var(--border);
}

.ghost-button {
  background: white;
  color: var(--text);
  border-color: var(--border);
}

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

.error-text {
  color: var(--danger);
  font-weight: 600;
  min-height: 1.2rem;
}

.fact-list {
  margin: 0;
  padding-left: 1.15rem;
  display: grid;
  gap: 8px;
}

.blueprint-list {
  display: grid;
  gap: 10px;
}

.blueprint-row {
  display: flex;
  justify-content: space-between;
  gap: 12px;
  padding: 10px 12px;
  border-radius: 12px;
  background: #f8fbff;
  border: 1px solid var(--border);
}

.quiz-main,
.quiz-side {
  display: flex;
  flex-direction: column;
  gap: 18px;
}

.quiz-topbar {
  display: grid;
  grid-template-columns: repeat(5, minmax(0, 1fr)) auto;
  gap: 12px;
  align-items: center;
}

.topbar-block {
  padding: 12px;
  background: #f8fbff;
  border-radius: 14px;
  border: 1px solid var(--border);
}

.question-wrap {
  display: flex;
  flex-direction: column;
  gap: 14px;
}

.question-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.question-text {
  display: grid;
  gap: 0.95rem;
  margin-bottom: 2px;
}

.question-prompt {
  margin: 0;
  line-height: 1.26;
  font-size: clamp(1.6rem, 3.8vw, 2.45rem);
}

.question-block {
  margin: 0;
  line-height: 1.6;
  font-size: 1.02rem;
  font-weight: 600;
}

.match-question {
  display: grid;
  gap: 1rem;
}

.assertion-reason-question {
  display: grid;
  gap: 1rem;
}

.pairing-question {
  display: grid;
  gap: 1rem;
}

.match-table-shell {
  overflow-x: auto;
}

.match-columns,
.statement-pair,
.pairing-grid {
  display: grid;
  gap: 12px;
}

.match-card,
.statement-card {
  min-width: 0;
  overflow: hidden;
  border: 1px solid var(--border);
  border-radius: 16px;
  background: #fbfdff;
}

.match-card-header,
.statement-card-header {
  padding: 0.9rem 1rem;
  border-bottom: 1px solid var(--border);
  background: linear-gradient(180deg, #f7faff 0%, #eef4ff 100%);
  font-size: 0.94rem;
  font-weight: 800;
  letter-spacing: 0.01em;
  text-transform: uppercase;
}

.match-table {
  width: 100%;
  border-collapse: collapse;
}

.match-table th,
.match-table td {
  padding: 0.9rem 1rem;
  border-bottom: 1px solid #e8eef8;
  vertical-align: top;
  text-align: left;
}

.match-table tr:last-child th,
.match-table tr:last-child td {
  border-bottom: none;
}

.match-table th {
  width: 3.5rem;
  color: #143a9b;
  background: #f8fbff;
  font-size: 0.94rem;
  font-weight: 800;
}

.match-table td {
  line-height: 1.55;
  font-size: 0.98rem;
}

.statement-card {
  display: grid;
  grid-template-rows: auto 1fr;
}

.statement-card-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}

.statement-card-assertion {
  border-color: #b8cffc;
  background: linear-gradient(180deg, #fcfdff 0%, #f6f9ff 100%);
}

.statement-card-assertion .statement-card-header {
  background: linear-gradient(180deg, #eef4ff 0%, #e4edff 100%);
}

.statement-card-reason {
  border-color: #cddbe9;
  background: linear-gradient(180deg, #fcfdff 0%, #f7fafc 100%);
}

.statement-card-reason .statement-card-header {
  background: linear-gradient(180deg, #f2f6fb 0%, #e8eef6 100%);
}

.statement-card-label {
  letter-spacing: 0.01em;
  text-transform: uppercase;
}

.statement-card-code {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 2rem;
  height: 2rem;
  padding: 0 0.55rem;
  border-radius: 999px;
  background: rgba(20, 58, 155, 0.1);
  color: #143a9b;
  font-size: 0.9rem;
  font-weight: 900;
}

.statement-card-text {
  margin: 0;
  padding: 1rem;
  line-height: 1.58;
  font-size: 1rem;
  font-weight: 650;
}

.assertion-reason-instruction {
  margin: 0;
  padding: 0.9rem 1rem;
  border: 1px dashed #bfd0ea;
  border-radius: 14px;
  background: #f8fbff;
  line-height: 1.5;
  font-size: 0.98rem;
  font-weight: 700;
  color: #33425d;
}

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

.pairing-card {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  gap: 0.9rem;
  align-items: start;
  padding: 1rem;
  border: 1px solid #d6e1f3;
  border-radius: 16px;
  background: linear-gradient(180deg, #fbfdff 0%, #f6f9ff 100%);
}

.pairing-card-number {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 2.35rem;
  height: 2.35rem;
  padding: 0 0.65rem;
  border-radius: 999px;
  background: #e6efff;
  color: #143a9b;
  font-size: 0.96rem;
  font-weight: 900;
}

.pairing-card-copy {
  display: grid;
  gap: 0.28rem;
}

.pairing-card-term {
  font-size: 1rem;
  font-weight: 800;
  line-height: 1.35;
  color: var(--text);
}

.pairing-card-detail {
  font-size: 0.98rem;
  line-height: 1.55;
  color: #33425d;
  font-weight: 600;
}

.pairing-question-instruction {
  margin: 0;
  padding: 0.95rem 1rem;
  border: 1px dashed #bfd0ea;
  border-radius: 14px;
  background: #f8fbff;
  line-height: 1.5;
  font-size: 1rem;
  font-weight: 700;
}

.options-wrap {
  display: grid;
  gap: 12px;
}

.option-button {
  width: 100%;
  text-align: left;
  background: #fcfdff;
  border: 1px solid var(--border);
  color: var(--text);
  padding: 14px 16px;
  border-radius: 14px;
  font-weight: 600;
}

.option-button .option-prefix {
  display: inline-flex;
  min-width: 30px;
  font-weight: 800;
}

.option-button.selected {
  background: var(--primary-soft);
  border-color: #8fb2ff;
  color: #143a9b;
}

.option-button.correct-preview {
  background: var(--success-soft);
}

.question-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 14px;
  align-items: center;
}

.legend {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-bottom: 14px;
}

.legend-item {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-size: 0.88rem;
  color: var(--muted);
}

.legend-color {
  width: 14px;
  height: 14px;
  border-radius: 50%;
  display: inline-block;
  border: 1px solid var(--border);
}

.legend-color.current {
  background: #dbe8ff;
  border-color: #7aa4ff;
}

.legend-color.answered {
  background: #e6f7ee;
  border-color: #89d3a7;
}

.legend-color.review {
  background: #fff4da;
  border-color: #f1c96b;
}

.legend-color.unanswered {
  background: #f3f6fb;
}

.palette {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(46px, 1fr));
  gap: 10px;
}

.palette-button {
  border: 1px solid var(--border);
  background: #f3f6fb;
  color: var(--text);
  font-weight: 700;
  min-height: 44px;
  padding: 0.5rem 0.25rem;
}

.palette-button.current {
  background: #dbe8ff;
  border-color: #7aa4ff;
}

.palette-button.answered {
  background: #e6f7ee;
  border-color: #89d3a7;
}

.palette-button.review {
  background: #fff4da;
  border-color: #f1c96b;
}

.palette-button.review.answered {
  background: linear-gradient(135deg, #e6f7ee 0 65%, #fff4da 65% 100%);
}

.summary-cards {
  display: grid;
  grid-template-columns: repeat(6, minmax(0, 1fr));
  gap: 14px;
  margin-bottom: 18px;
}

.summary-card {
  padding: 16px;
  border-radius: 14px;
  border: 1px solid var(--border);
  background: #f8fbff;
}

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

.summary-card .value {
  font-size: 1.5rem;
  font-weight: 800;
  margin-top: 6px;
}

.weak-topic-row,
.revision-row {
  display: grid;
  gap: 6px;
  padding: 12px 14px;
  border-radius: 14px;
  border: 1px solid var(--border);
  background: #fbfdff;
  margin-bottom: 10px;
}

.progress-bar {
  height: 10px;
  border-radius: 999px;
  background: #eef2f8;
  overflow: hidden;
}

.progress-bar span {
  display: block;
  height: 100%;
  background: var(--primary);
}

.review-list {
  display: grid;
  gap: 14px;
}

.review-card {
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: 16px;
  background: #fcfdff;
}

.review-card.skipped {
  background: #fffdf4;
}

.review-topline {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 10px;
}

.review-question {
  font-weight: 700;
  line-height: 1.5;
}

.answer-line {
  margin-top: 10px;
  line-height: 1.5;
}

.answer-line strong {
  display: inline-block;
  min-width: 126px;
}

.review-note {
  margin-top: 12px;
  padding: 12px 14px;
  border-radius: 12px;
  background: #f8fbff;
  border: 1px solid var(--border);
}

.site-footer {
  margin-top: 18px;
  color: var(--muted);
  font-size: 0.92rem;
}

@media (max-width: 1100px) {
  .home-grid,
  .quiz-layout,
  .results-grid,
  .summary-cards {
    grid-template-columns: 1fr;
  }

  .quiz-topbar {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

@media (max-width: 720px) {
  .page-shell {
    width: min(100% - 16px, 100%);
    margin: 12px auto 32px;
  }

  .card {
    padding: 16px;
  }

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

  .site-header {
    flex-direction: column;
  }

  .quiz-topbar {
    grid-template-columns: 1fr 1fr;
  }

  .topbar-actions {
    grid-column: 1 / -1;
  }

  .question-prompt {
    font-size: clamp(1.45rem, 7vw, 1.9rem);
  }

  .match-table th,
  .match-table td {
    padding: 0.8rem 0.85rem;
  }

  .pairing-card {
    grid-template-columns: 1fr;
    gap: 0.75rem;
  }

  .pairing-card-number {
    min-width: 2rem;
    height: 2rem;
  }
}

@media (min-width: 860px) {
  .match-columns {
    grid-template-columns: minmax(0, 0.78fr) minmax(0, 1.22fr);
  }

  .statement-pair {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .pairing-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}