:root {
  color-scheme: light;
  --bg: #f3f7fb;
  --bg-accent: radial-gradient(circle at top, rgba(59, 130, 246, 0.15), transparent 45%),
    linear-gradient(180deg, #f8fbff 0%, #eef4fb 100%);
  --panel: rgba(255, 255, 255, 0.92);
  --panel-strong: #ffffff;
  --panel-border: rgba(15, 23, 42, 0.12);
  --text: #10223b;
  --muted: #53657f;
  --accent: #2563eb;
  --accent-strong: #1d4ed8;
  --accent-soft: rgba(37, 99, 235, 0.12);
  --success: #0f9f6e;
  --success-soft: rgba(15, 159, 110, 0.14);
  --warning: #b7791f;
  --warning-soft: rgba(183, 121, 31, 0.14);
  --danger: #c0392b;
  --danger-soft: rgba(192, 57, 43, 0.14);
  --shadow: 0 16px 40px rgba(15, 23, 42, 0.08);
  --focus: 0 0 0 3px rgba(37, 99, 235, 0.25);
  --radius: 1rem;
  --radius-sm: 0.75rem;
  --font-stack: Inter, Segoe UI, Arial, Helvetica, sans-serif;
}

:root[data-theme='dark'] {
  color-scheme: dark;
  --bg: #08111f;
  --bg-accent: radial-gradient(circle at top, rgba(56, 189, 248, 0.16), transparent 42%),
    linear-gradient(180deg, #09111f 0%, #050b14 100%);
  --panel: rgba(9, 17, 31, 0.92);
  --panel-strong: #0f1b30;
  --panel-border: rgba(148, 163, 184, 0.2);
  --text: #e5edf8;
  --muted: #9db0ca;
  --accent: #7dd3fc;
  --accent-strong: #38bdf8;
  --accent-soft: rgba(56, 189, 248, 0.14);
  --success: #4ade80;
  --success-soft: rgba(74, 222, 128, 0.14);
  --warning: #fbbf24;
  --warning-soft: rgba(251, 191, 36, 0.16);
  --danger: #f87171;
  --danger-soft: rgba(248, 113, 113, 0.16);
  --shadow: 0 18px 48px rgba(0, 0, 0, 0.28);
  --focus: 0 0 0 3px rgba(125, 211, 252, 0.3);
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  min-height: 100vh;
  font-family: var(--font-stack);
  color: var(--text);
  background: var(--bg-accent);
}

button,
a {
  transition: background-color 150ms ease, border-color 150ms ease, color 150ms ease, transform 150ms ease;
}

button:focus-visible,
a:focus-visible {
  outline: none;
  box-shadow: var(--focus);
}

.skip-link {
  position: absolute;
  top: -3rem;
  left: 1rem;
  z-index: 20;
  padding: 0.75rem 1rem;
  border-radius: 999px;
  background: var(--panel-strong);
  color: var(--text);
}

.skip-link:focus {
  top: 1rem;
}

.page-shell {
  width: min(1400px, calc(100% - 1.5rem));
  margin: 0 auto;
  padding: 1rem 0 1.5rem;
}

.site-header,
.site-footer,
.status-strip,
.panel {
  backdrop-filter: blur(16px);
}

.site-header {
  display: flex;
  justify-content: space-between;
  gap: 1rem;
  align-items: flex-start;
  margin-bottom: 1rem;
  padding: 1.4rem;
  border: 1px solid var(--panel-border);
  border-radius: calc(var(--radius) + 0.25rem);
  background: var(--panel);
  box-shadow: var(--shadow);
}

.eyebrow {
  margin: 0 0 0.5rem;
  color: var(--accent-strong);
  font-weight: 700;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  font-size: 0.82rem;
}

h1,
h2,
h3,
p {
  margin-top: 0;
}

h1 {
  margin-bottom: 0.75rem;
  font-size: clamp(2rem, 3.4vw, 3.2rem);
}

.site-intro,
.muted {
  color: var(--muted);
}

.header-actions {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.toggle-button,
.secondary-button,
.primary-button,
.choice-button,
.ghost-button,
.scenario-card {
  border: 1px solid var(--panel-border);
  border-radius: 0.9rem;
  font: inherit;
  cursor: pointer;
}

.toggle-button,
.secondary-button,
.ghost-button {
  padding: 0.75rem 1rem;
  background: var(--panel-strong);
  color: var(--text);
}

.primary-button {
  padding: 0.85rem 1.15rem;
  background: linear-gradient(135deg, var(--accent), var(--accent-strong));
  color: #fff;
  border-color: transparent;
  font-weight: 700;
}

.primary-button:hover,
.secondary-button:hover,
.ghost-button:hover,
.choice-button:hover,
.toggle-button:hover,
.scenario-card:hover {
  transform: translateY(-1px);
}

.status-strip {
  min-height: 3.25rem;
  margin-bottom: 1rem;
  padding: 0.9rem 1.1rem;
  border: 1px solid var(--panel-border);
  border-radius: var(--radius);
  background: var(--panel);
  color: var(--muted);
  box-shadow: var(--shadow);
}

.workspace {
  display: grid;
  grid-template-columns: minmax(250px, 290px) minmax(0, 1fr) minmax(0, 380px);
  gap: 1rem;
  align-items: start;
}

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

.panel--sidebar,
.panel--tree {
  padding: 1rem;
  position: sticky;
  top: 1rem;
}

.panel--main {
  padding: 1.25rem;
}

.section-label {
  display: inline-flex;
  align-items: center;
  gap: 0.45rem;
  padding: 0.3rem 0.7rem;
  border-radius: 999px;
  background: var(--accent-soft);
  color: var(--accent-strong);
  font-size: 0.84rem;
  font-weight: 700;
}

.scenario-list {
  display: grid;
  gap: 0.85rem;
}

.scenario-card {
  width: 100%;
  text-align: left;
  padding: 1rem;
  background: var(--panel-strong);
}

.scenario-card.is-active {
  border-color: var(--accent);
  background: linear-gradient(180deg, var(--accent-soft), transparent);
}

.card-meta,
.inline-stats,
.footer-links,
.toolbar {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.stat-pill,
.verdict-pill,
.phase-pill {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  padding: 0.28rem 0.65rem;
  border-radius: 999px;
  font-size: 0.8rem;
  font-weight: 700;
}

.stat-pill,
.phase-pill {
  background: rgba(148, 163, 184, 0.14);
  color: var(--muted);
}

.verdict-pill.good,
.feedback.good,
.outcome-banner.success {
  background: var(--success-soft);
  color: var(--success);
}

.verdict-pill.bad,
.feedback.bad,
.outcome-banner.failure {
  background: var(--danger-soft);
  color: var(--danger);
}

.verdict-pill.neutral,
.feedback.neutral,
.outcome-banner.mixed {
  background: var(--warning-soft);
  color: var(--warning);
}

.toolbar {
  justify-content: space-between;
  margin-bottom: 1rem;
}

.hero-grid,
.score-grid,
.reference-grid {
  display: grid;
  gap: 1rem;
}

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

.surface,
.feedback,
.terminal-panel,
.breadcrumbs,
.reference-card,
.tree-node-box {
  border: 1px solid var(--panel-border);
  border-radius: var(--radius-sm);
  background: var(--panel-strong);
}

.surface,
.terminal-panel,
.reference-card,
.tree-node-box,
.feedback,
.breadcrumbs {
  padding: 1rem;
}

.choice-list,
.breadcrumb-list,
.citation-list,
.summary-list,
.tree-list,
.tree-list ul {
  list-style: none;
  padding: 0;
  margin: 0;
}

.choice-list {
  display: grid;
  gap: 0.85rem;
  margin-top: 1rem;
}

.choice-button {
  width: 100%;
  text-align: left;
  padding: 1rem;
  background: var(--panel-strong);
  color: var(--text);
}

.choice-button strong {
  display: block;
  margin-bottom: 0.3rem;
}

.choice-button small,
.card-meta,
.citation-list a,
.summary-list li span:last-child {
  color: var(--muted);
}

.choice-button.selected {
  border-color: var(--accent);
  background: var(--accent-soft);
}

.choice-button:disabled {
  cursor: not-allowed;
  opacity: 1;
}

.breadcrumbs {
  margin: 1rem 0;
}

.breadcrumb-list,
.summary-list {
  display: grid;
  gap: 0.75rem;
}

.breadcrumb-item {
  display: grid;
  gap: 0.35rem;
  padding-left: 0.75rem;
  border-left: 3px solid rgba(148, 163, 184, 0.28);
}

.citation-list {
  display: grid;
  gap: 0.45rem;
}

.citation-list a {
  word-break: break-word;
}

.outcome-banner {
  padding: 1rem;
  border-radius: var(--radius-sm);
  font-weight: 700;
}

.score-grid {
  grid-template-columns: repeat(3, minmax(0, 1fr));
  margin: 1rem 0;
}

.score-card {
  padding: 1rem;
  text-align: center;
  border: 1px solid var(--panel-border);
  border-radius: var(--radius-sm);
  background: var(--panel-strong);
}

.score-card strong {
  display: block;
  font-size: 1.8rem;
}

.reference-grid {
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  margin-top: 1rem;
}

.panel--tree.is-hidden {
  display: none;
}

.tree-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 0.75rem;
  margin-bottom: 1rem;
}

.tree-list {
  display: grid;
  gap: 0.8rem;
}

.tree-list ul {
  margin-top: 0.8rem;
  margin-left: 1rem;
  padding-left: 1rem;
  border-left: 2px solid rgba(148, 163, 184, 0.2);
}

.tree-branch {
  margin-top: 0.75rem;
}

.tree-branch-label {
  display: inline-flex;
  align-items: center;
  gap: 0.45rem;
  padding: 0.45rem 0.7rem;
  border-radius: 999px;
  background: rgba(148, 163, 184, 0.12);
  color: var(--text);
  font-size: 0.88rem;
}

.tree-branch--taken > .tree-branch-label,
.tree-node--active > .tree-node-box {
  border-color: var(--accent);
  background: var(--accent-soft);
}

.tree-node--visited > .tree-node-box {
  border-color: rgba(37, 99, 235, 0.3);
}

.tree-node--terminal-success > .tree-node-box {
  border-color: rgba(15, 159, 110, 0.45);
}

.tree-node--terminal-failure > .tree-node-box {
  border-color: rgba(192, 57, 43, 0.45);
}

.key-hint {
  color: var(--muted);
  font-size: 0.9rem;
}

.empty-state {
  padding: 2rem 1rem;
  text-align: center;
}

.site-footer {
  margin-top: 1rem;
  padding: 1rem;
  text-align: center;
  color: var(--muted);
}

.site-footer a {
  color: var(--accent-strong);
}

.noscript-banner {
  margin: 1rem auto;
  width: min(900px, calc(100% - 2rem));
  padding: 1rem;
  border-radius: var(--radius-sm);
  background: var(--danger-soft);
  color: var(--danger);
}

@media (max-width: 1120px) {
  .workspace {
    grid-template-columns: minmax(240px, 290px) minmax(0, 1fr);
  }

  .panel--tree {
    grid-column: 1 / -1;
    position: static;
  }
}

@media (max-width: 820px) {
  .page-shell {
    width: min(100%, calc(100% - 1rem));
  }

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

  .workspace,
  .hero-grid,
  .score-grid {
    grid-template-columns: 1fr;
  }

  .panel--sidebar {
    position: static;
  }

  .toolbar {
    flex-direction: column;
    align-items: stretch;
  }
}

@media (max-width: 560px) {
  .panel--main,
  .panel--sidebar,
  .panel--tree,
  .status-strip,
  .site-header {
    padding: 1rem;
  }

  .choice-button,
  .primary-button,
  .secondary-button,
  .ghost-button,
  .toggle-button,
  .scenario-card {
    width: 100%;
  }
}