:root {
  color-scheme: light;

  --md-sys-color-primary: #0b57d0;
  --md-sys-color-on-primary: #ffffff;
  --md-sys-color-primary-container: #d7e3ff;
  --md-sys-color-on-primary-container: #041e49;
  --md-sys-color-secondary-container: #dfe6f2;
  --md-sys-color-on-secondary-container: #1f2a44;
  --md-sys-color-surface: #f8fafd;
  --md-sys-color-surface-container: #f0f4f9;
  --md-sys-color-surface-container-high: #e9eef6;
  --md-sys-color-on-surface: #1f1f1f;
  --md-sys-color-on-surface-variant: #444746;
  --md-sys-color-outline: #747775;
  --md-sys-color-outline-variant: #c4c7c5;
  --md-sys-color-error: #b3261e;
  --md-sys-color-error-container: #f9dedc;
  --md-sys-color-on-error-container: #410e0b;

  --md-sys-shape-corner-medium: 12px;
  --md-sys-shape-corner-large: 20px;
  --md-sys-shape-corner-full: 999px;
  --font:
    "Roboto", "Noto Sans SC", "PingFang SC", "Microsoft YaHei", system-ui,
    sans-serif;
}

* {
  box-sizing: border-box;
}

html {
  background: var(--md-sys-color-surface);
  scroll-behavior: smooth;
}

body {
  min-width: 320px;
  min-height: 100vh;
  margin: 0;
  background: var(--md-sys-color-surface);
  color: var(--md-sys-color-on-surface);
  font-family: var(--font);
  font-size: 16px;
  line-height: 1.5;
}

button,
input {
  font: inherit;
}

.skip-link {
  position: fixed;
  top: 8px;
  left: 8px;
  z-index: 20;
  padding: 8px 16px;
  border-radius: var(--md-sys-shape-corner-full);
  background: var(--md-sys-color-primary);
  color: var(--md-sys-color-on-primary);
  font-size: 14px;
  font-weight: 500;
  text-decoration: none;
  transform: translateY(-160%);
}

.skip-link:focus {
  transform: translateY(0);
}

.top-app-bar {
  height: 64px;
  background: var(--md-sys-color-surface);
}

.top-app-bar__content,
.page {
  width: min(720px, calc(100% - 48px));
  margin-inline: auto;
}

.top-app-bar__content {
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.top-app-bar__nav {
  display: flex;
  align-items: center;
}

.top-app-bar h1 {
  margin: 0;
  font-size: 22px;
  font-weight: 500;
  line-height: 28px;
  letter-spacing: 0;
}

.text-link {
  min-height: 40px;
  padding-inline: 12px;
  display: inline-flex;
  align-items: center;
  border-radius: var(--md-sys-shape-corner-full);
  color: var(--md-sys-color-primary);
  font-size: 14px;
  font-weight: 500;
  text-decoration: none;
}

.text-link:hover {
  background: color-mix(in srgb, var(--md-sys-color-primary) 8%, transparent);
}

.page {
  padding: 24px 0 calc(144px + env(safe-area-inset-bottom));
}

.practice-shell {
  overflow: hidden;
  border-radius: var(--md-sys-shape-corner-large);
  background: var(--md-sys-color-surface-container);
}

.floating-controls {
  width: min(720px, calc(100% - 32px));
  min-height: 64px;
  padding: 10px 12px 10px 16px;
  position: fixed;
  z-index: 10;
  bottom: calc(16px + env(safe-area-inset-bottom));
  left: 50%;
  display: grid;
  grid-template-columns: auto auto auto 1fr auto;
  align-items: center;
  gap: 20px;
  border: 1px solid var(--md-sys-color-outline-variant);
  border-radius: var(--md-sys-shape-corner-large);
  background: var(--md-sys-color-surface);
  box-shadow: 0 2px 8px rgb(60 64 67 / 16%);
  color: var(--md-sys-color-on-surface-variant);
  font-size: 13px;
  line-height: 20px;
  transform: translateX(-50%);
}

.floating-metric {
  min-width: 54px;
  display: flex;
  flex-direction: column;
}

.floating-metric span {
  font-size: 11px;
  line-height: 16px;
}

.floating-metric strong {
  color: var(--md-sys-color-on-surface);
  font-weight: 500;
  font-variant-numeric: tabular-nums;
}

.display-mode {
  display: flex;
  align-items: center;
  gap: 10px;
  justify-self: end;
}

.display-mode label {
  cursor: pointer;
}

.display-mode input {
  width: 52px;
  height: 32px;
  margin: 0;
  padding: 2px;
  position: relative;
  appearance: none;
  border: 2px solid var(--md-sys-color-outline);
  border-radius: var(--md-sys-shape-corner-full);
  background: var(--md-sys-color-surface-container-high);
  cursor: pointer;
  transition:
    background-color 150ms ease,
    border-color 150ms ease;
}

.display-mode input::after {
  content: "";
  width: 16px;
  height: 16px;
  position: absolute;
  top: 6px;
  left: 6px;
  border-radius: 50%;
  background: var(--md-sys-color-outline);
  transition:
    width 150ms ease,
    height 150ms ease,
    top 150ms ease,
    left 150ms ease,
    background-color 150ms ease;
}

.display-mode input:checked {
  border-color: var(--md-sys-color-primary);
  background: var(--md-sys-color-primary);
}

.display-mode input:checked::after {
  width: 24px;
  height: 24px;
  top: 2px;
  left: 22px;
  background: var(--md-sys-color-on-primary);
}

.display-mode input:focus-visible {
  outline: 3px solid color-mix(in srgb, var(--md-sys-color-primary) 28%, transparent);
  outline-offset: 2px;
}

.floating-controls .button {
  min-height: 44px;
  white-space: nowrap;
}

.empty-state {
  min-height: 260px;
  padding: 48px 24px 32px;
  display: flex;
  align-items: center;
  flex-direction: column;
  justify-content: center;
  text-align: center;
}

.empty-state h2 {
  margin: 0;
  font-size: 24px;
  font-weight: 400;
  line-height: 32px;
}

.empty-state p {
  margin: 8px 0 0;
  color: var(--md-sys-color-on-surface-variant);
  font-size: 14px;
  line-height: 20px;
}

.question-grid {
  display: block;
}

.premises-panel,
.conclusion-panel {
  margin: 0;
  padding: 28px 24px;
  border: 0;
}

.premises-panel:focus {
  outline: none;
}

.conclusion-panel {
  border-top: 1px solid var(--md-sys-color-outline-variant);
}

.section-label,
.conclusion-panel legend {
  margin: 0 0 16px;
  padding: 0;
  color: var(--md-sys-color-on-surface);
  font-size: 16px;
  font-weight: 500;
  line-height: 24px;
}

.conclusion-panel legend {
  width: 100%;
  float: left;
}

.conclusion-panel legend + * {
  clear: both;
}

.premises-list {
  margin: 0;
  padding: 0;
  overflow: hidden;
  border-radius: var(--md-sys-shape-corner-medium);
  background: var(--md-sys-color-surface);
  list-style: none;
}

.premise {
  min-height: 56px;
  padding: 12px 16px;
  display: grid;
  grid-template-columns: 28px minmax(0, 1fr);
  align-items: center;
  gap: 8px;
  border-bottom: 1px solid var(--md-sys-color-outline-variant);
}

.premise:last-child {
  border-bottom: 0;
}

.premise__number {
  color: var(--md-sys-color-on-surface-variant);
  font-size: 12px;
  font-variant-numeric: tabular-nums;
  line-height: 16px;
}

.premise__copy {
  font-size: 16px;
  line-height: 24px;
}

.conclusion-card {
  margin-bottom: 16px;
  padding: 20px;
  border-radius: var(--md-sys-shape-corner-medium);
  background: var(--md-sys-color-primary-container);
  color: var(--md-sys-color-on-primary-container);
}

.conclusion-card__label {
  display: block;
  margin-bottom: 4px;
  font-size: 12px;
  font-weight: 500;
  line-height: 16px;
}

.conclusion-card strong {
  display: block;
  font-size: 20px;
  font-weight: 500;
  line-height: 28px;
}

.judgment-options {
  margin: 0 0 20px;
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 12px;
}

.judgment-option {
  min-height: 56px;
  padding: 8px 16px;
  display: flex;
  align-items: center;
  gap: 12px;
  border: 1px solid var(--md-sys-color-outline);
  border-radius: var(--md-sys-shape-corner-medium);
  background: transparent;
  color: var(--md-sys-color-on-surface);
  cursor: pointer;
  font-size: 14px;
  font-weight: 500;
  line-height: 20px;
  transition:
    background-color 120ms ease,
    border-color 120ms ease;
}

.judgment-option:hover {
  background: color-mix(in srgb, var(--md-sys-color-on-surface) 6%, transparent);
}

.judgment-option:focus-within {
  outline: 3px solid color-mix(in srgb, var(--md-sys-color-primary) 24%, transparent);
  outline-offset: 1px;
}

.judgment-option input {
  width: 20px;
  height: 20px;
  margin: 0;
  flex: 0 0 auto;
  accent-color: var(--md-sys-color-primary);
  cursor: pointer;
}

.judgment-option--selected {
  border-color: var(--md-sys-color-primary);
  background: color-mix(
    in srgb,
    var(--md-sys-color-primary-container) 62%,
    transparent
  );
}

.judgment-option--correct {
  border-color: var(--md-sys-color-primary);
  background: var(--md-sys-color-primary-container);
  color: var(--md-sys-color-on-primary-container);
}

.judgment-option--wrong {
  border-color: var(--md-sys-color-error);
  background: var(--md-sys-color-error-container);
  color: var(--md-sys-color-on-error-container);
}

.button {
  min-width: 96px;
  min-height: 40px;
  padding: 0 24px;
  border: 0;
  border-radius: var(--md-sys-shape-corner-full);
  cursor: pointer;
  font-size: 14px;
  font-weight: 500;
  line-height: 20px;
  letter-spacing: 0.1px;
  transition:
    background-color 120ms ease,
    color 120ms ease;
}

.button:focus-visible,
.text-link:focus-visible {
  outline: 3px solid color-mix(in srgb, var(--md-sys-color-primary) 28%, transparent);
  outline-offset: 2px;
}

.button--primary {
  background: var(--md-sys-color-primary);
  color: var(--md-sys-color-on-primary);
}

.button--primary:hover:not(:disabled) {
  background: color-mix(in srgb, var(--md-sys-color-primary) 92%, black);
}

.button--primary:disabled {
  background: color-mix(in srgb, var(--md-sys-color-on-surface) 12%, transparent);
  color: color-mix(in srgb, var(--md-sys-color-on-surface) 38%, transparent);
  cursor: not-allowed;
}

.button--tonal {
  background: var(--md-sys-color-secondary-container);
  color: var(--md-sys-color-on-secondary-container);
}

.button--tonal:hover {
  background: color-mix(
    in srgb,
    var(--md-sys-color-secondary-container) 92%,
    var(--md-sys-color-on-secondary-container)
  );
}

.feedback {
  padding: 24px;
  border-top: 1px solid var(--md-sys-color-outline-variant);
  color: var(--md-sys-color-on-surface);
}

.feedback__result {
  padding: 20px;
  border-radius: var(--md-sys-shape-corner-medium);
  background: var(--md-sys-color-primary-container);
  color: var(--md-sys-color-on-primary-container);
}

.feedback--retry .feedback__result {
  background: var(--md-sys-color-error-container);
  color: var(--md-sys-color-on-error-container);
}

.feedback__result h2 {
  margin: 0;
  font-size: 20px;
  font-weight: 500;
  line-height: 28px;
}

.feedback__result p {
  margin: 4px 0 0;
  font-size: 14px;
  line-height: 20px;
}

.feedback__review {
  margin: 20px 4px 0;
  padding-bottom: 20px;
  border-bottom: 1px solid var(--md-sys-color-outline-variant);
}

.feedback__review > span {
  display: block;
  margin-bottom: 4px;
  font-size: 12px;
  font-weight: 500;
  line-height: 16px;
}

.answer-verdict {
  display: flex;
  align-items: baseline;
  gap: 10px;
}

.answer-verdict strong {
  font-size: 14px;
  font-weight: 700;
  line-height: 20px;
}

.answer-verdict span {
  font-size: 14px;
  line-height: 20px;
}

.post-analysis {
  margin-top: 24px;
}

.post-analysis h3,
.post-analysis h4 {
  margin: 0;
  font-weight: 500;
}

.post-analysis h3 {
  font-size: 20px;
  line-height: 28px;
}

.post-analysis h4 {
  margin-top: 24px;
  font-size: 16px;
  line-height: 24px;
}

.analysis-intro,
.countermodel-mapping,
.countermodel-domain {
  margin: 8px 0 0;
  color: var(--md-sys-color-on-surface-variant);
  font-size: 14px;
  line-height: 20px;
}

.countermodel-mapping {
  padding: 10px 12px;
  border-radius: 8px;
  background: var(--md-sys-color-secondary-container);
  color: var(--md-sys-color-on-secondary-container);
}

.countermodel-domain strong {
  color: var(--md-sys-color-on-surface);
  font-weight: 500;
}

.fitch-proof,
.countermodel-objects,
.countermodel-checks {
  margin: 16px 0 0;
  overflow: hidden;
  border-radius: var(--md-sys-shape-corner-medium);
  background: var(--md-sys-color-surface);
}

.proof-line {
  min-height: 48px;
  padding: 10px 14px;
  display: grid;
  grid-template-columns: 24px minmax(0, 1fr) auto;
  align-items: baseline;
  gap: 10px;
  border-bottom: 1px solid var(--md-sys-color-outline-variant);
}

.fitch-proof > .proof-line:last-child,
.fitch-subproof .proof-line:last-child {
  border-bottom: 0;
}

.proof-line__number {
  color: var(--md-sys-color-on-surface-variant);
  font-size: 12px;
  font-variant-numeric: tabular-nums;
  line-height: 20px;
  text-align: right;
}

.proof-line__formula {
  min-width: 0;
  font-size: 15px;
  line-height: 24px;
  overflow-wrap: anywhere;
}

.proof-line__reason {
  color: var(--md-sys-color-on-surface-variant);
  font-size: 12px;
  line-height: 20px;
  text-align: right;
  white-space: nowrap;
}

.fitch-subproof {
  margin: 0 12px 0 28px;
  border-left: 2px solid var(--md-sys-color-primary);
  background: color-mix(
    in srgb,
    var(--md-sys-color-primary-container) 24%,
    var(--md-sys-color-surface)
  );
}

.fitch-subproof > .fitch-subproof {
  margin-left: 20px;
}

.proof-line--assumption {
  border-bottom-color: var(--md-sys-color-outline);
}

.proof-line--contradiction .proof-line__formula {
  color: var(--md-sys-color-error);
  font-weight: 700;
}

.proof-system {
  margin-top: 16px;
  border-top: 1px solid var(--md-sys-color-outline-variant);
  border-bottom: 1px solid var(--md-sys-color-outline-variant);
}

.proof-system summary {
  min-height: 48px;
  display: flex;
  align-items: center;
  color: var(--md-sys-color-primary);
  cursor: pointer;
  font-size: 14px;
  font-weight: 500;
  line-height: 20px;
}

.proof-system > p,
.proof-system ul {
  color: var(--md-sys-color-on-surface-variant);
  font-size: 13px;
  line-height: 20px;
}

.proof-system > p {
  margin: 0 0 12px;
}

.proof-system ul {
  margin: 0 0 12px;
  padding-left: 22px;
}

.proof-system li + li {
  margin-top: 4px;
}

.proof-system__source a {
  color: var(--md-sys-color-primary);
}

.countermodel-objects {
  padding: 0;
}

.countermodel-objects > div {
  min-height: 48px;
  padding: 10px 14px;
  display: grid;
  grid-template-columns: 32px minmax(0, 1fr);
  gap: 10px;
  border-bottom: 1px solid var(--md-sys-color-outline-variant);
}

.countermodel-objects > div:last-child {
  border-bottom: 0;
}

.countermodel-objects dt {
  color: var(--md-sys-color-primary);
  font-weight: 700;
}

.countermodel-objects dd {
  margin: 0;
}

.countermodel-checks {
  padding: 0;
  list-style: none;
}

.countermodel-checks li {
  padding: 14px;
  border-bottom: 1px solid var(--md-sys-color-outline-variant);
}

.countermodel-checks li:last-child {
  border-bottom: 0;
}

.countermodel-check__status {
  display: block;
  margin-bottom: 3px;
  color: var(--md-sys-color-primary);
  font-size: 12px;
  font-weight: 500;
  line-height: 16px;
}

.countermodel-check--conclusion .countermodel-check__status {
  color: var(--md-sys-color-error);
}

.countermodel-checks strong {
  display: block;
  font-size: 14px;
  font-weight: 500;
  line-height: 20px;
}

.countermodel-checks p {
  margin: 4px 0 0;
  color: var(--md-sys-color-on-surface-variant);
  font-size: 13px;
  line-height: 20px;
}

.sr-only {
  position: absolute !important;
  width: 1px !important;
  height: 1px !important;
  padding: 0 !important;
  overflow: hidden !important;
  clip: rect(0, 0, 0, 0) !important;
  white-space: nowrap !important;
  border: 0 !important;
}

[hidden] {
  display: none !important;
}

@media (max-width: 599px) {
  .top-app-bar__content,
  .page {
    width: min(100% - 32px, 720px);
  }

  .page {
    padding-top: 16px;
    padding-bottom: calc(160px + env(safe-area-inset-bottom));
  }

  .floating-controls {
    width: calc(100% - 16px);
    min-height: 0;
    padding: 10px;
    bottom: calc(8px + env(safe-area-inset-bottom));
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 10px 8px;
    border-radius: 16px;
  }

  .floating-metric {
    min-width: 0;
  }

  .floating-controls .display-mode {
    grid-column: 1 / 3;
    justify-self: start;
  }

  .floating-controls .button {
    width: 100%;
    min-width: 0;
    padding-inline: 12px;
    grid-column: 3;
  }

  .empty-state {
    min-height: 220px;
    padding-inline: 20px;
  }

  .premises-panel,
  .conclusion-panel {
    padding: 24px 16px;
  }

  .premise {
    padding-inline: 12px;
    grid-template-columns: 24px minmax(0, 1fr);
  }

  .judgment-options {
    grid-template-columns: 1fr;
  }

  .button--primary {
    width: 100%;
  }

  .feedback {
    padding: 24px 16px;
  }

  .answer-verdict {
    align-items: flex-start;
    flex-direction: column;
    gap: 2px;
  }

  .proof-line {
    grid-template-columns: 22px minmax(0, 1fr);
    gap: 2px 8px;
  }

  .proof-line__reason {
    grid-column: 2;
    text-align: left;
    white-space: normal;
  }

  .fitch-subproof {
    margin-right: 6px;
    margin-left: 14px;
  }

}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }

  *,
  *::before,
  *::after {
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
}