:root {
  color-scheme: dark;
  --bg: #07101b;
  --bg-elevated: #0f1b2c;
  --panel: rgba(13, 25, 40, 0.94);
  --panel-soft: rgba(18, 33, 53, 0.9);
  --line: rgba(155, 190, 255, 0.18);
  --line-strong: rgba(155, 190, 255, 0.34);
  --ink: #f3f8ff;
  --muted: #a8b8d4;
  --brand: #7fd6ff;
  --brand-strong: #d7f6ff;
  --accent: #9d8cff;
  --gold: #ffd782;
  --shadow: 0 24px 70px rgba(0, 0, 0, 0.34);
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  background:
    radial-gradient(circle at top, rgba(127, 214, 255, 0.18), transparent 28%),
    linear-gradient(180deg, #07101b 0%, #0b1320 100%);
  color: var(--ink);
  line-height: 1.55;
}

a { color: var(--brand); text-decoration: none; }
a:hover { text-decoration: underline; }

.site-shell {
  width: min(1120px, calc(100% - 32px));
  margin: 0 auto;
  padding: 24px 0 56px;
}

.site-header,
.site-footer {
  display: flex;
  justify-content: space-between;
  gap: 20px;
  align-items: flex-start;
}

.site-header { margin-bottom: 24px; }
.site-footer {
  margin-top: 28px;
  padding-top: 18px;
  border-top: 1px solid var(--line);
}

.brand {
  display: inline-block;
  font-size: 1.25rem;
  font-weight: 800;
  color: var(--ink);
  letter-spacing: 0.03em;
}

.tagline,
.footer-meta,
.disclaimer,
.hero-copy,
.feedback-card p,
.summary-item p,
.copy-panel p,
.content-panel p,
.content-panel li,
.cue-card p,
.window-cell span {
  color: var(--muted);
}

.tagline {
  margin: 6px 0 0;
  font-size: 0.95rem;
}

.site-nav,
.footer-links,
.action-row,
.summary-actions {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
}

.nav-link,
.ghost-button,
.primary-button,
.card,
.legend-card,
.feedback-card,
.summary-item,
.notice-panel,
.content-panel,
.copy-panel,
.cue-card,
.window-cell,
.stat-card {
  border-radius: 22px;
}

.nav-link {
  padding: 10px 14px;
  color: var(--muted);
  border: 1px solid transparent;
}

.nav-link.is-active,
.nav-link:hover {
  color: var(--ink);
  border-color: var(--line);
  background: rgba(255, 255, 255, 0.03);
  text-decoration: none;
}

.page {
  display: grid;
  gap: 20px;
}

.card,
.notice-panel,
.content-panel,
.copy-panel,
.game-panel {
  background: var(--panel);
  border: 1px solid var(--line);
  box-shadow: var(--shadow);
  padding: 24px;
}

.hero-panel {
  display: grid;
  grid-template-columns: minmax(0, 1.15fr) minmax(260px, 0.85fr);
  gap: 20px;
}

.eyebrow {
  display: inline-block;
  font-size: 0.78rem;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--brand);
  font-weight: 700;
  margin-bottom: 12px;
}

h1, h2, h3 {
  line-height: 1.1;
  margin: 0 0 14px;
}

h1 { font-size: clamp(2.1rem, 6vw, 4rem); }
h2 { font-size: clamp(1.3rem, 3vw, 1.9rem); }
h3 { font-size: clamp(1.08rem, 2vw, 1.45rem); }

.hero-copy {
  max-width: 58ch;
  font-size: 1.06rem;
}

.hero-list,
.bullet-list,
.number-list {
  margin: 18px 0 0;
  padding-left: 20px;
}

.hero-list li,
.bullet-list li,
.number-list li {
  margin-bottom: 10px;
}

.hero-stats,
.summary-metrics,
.legend-grid {
  display: grid;
  gap: 14px;
}

.hero-stats,
.summary-metrics {
  grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
  align-content: start;
}

.legend-grid {
  grid-template-columns: repeat(auto-fit, minmax(170px, 1fr));
  margin: 20px 0;
}

.stat-card,
.legend-card,
.summary-item,
.window-cell {
  background: var(--panel-soft);
  border: 1px solid var(--line);
  padding: 16px;
}

.stat-card span,
.legend-card span,
.mini-label,
.summary-item span {
  display: block;
  color: var(--muted);
  font-size: 0.83rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
}

.stat-card strong,
.legend-card strong,
.summary-item strong {
  display: block;
  margin-top: 8px;
  font-size: 1.05rem;
}

.notice-panel h2,
.panel-head h2,
.section-heading h2,
.content-panel h1 {
  margin-bottom: 10px;
}

.panel-head,
.progress-row {
  display: flex;
  justify-content: space-between;
  gap: 12px;
  align-items: center;
}

.progress-row {
  border: 1px solid var(--line);
  background: rgba(255, 255, 255, 0.02);
  padding: 14px 16px;
  border-radius: 18px;
  margin-bottom: 18px;
}

.progress-row strong {
  display: block;
  margin-top: 4px;
  font-size: 1.1rem;
}

.status-pill {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  border-radius: 999px;
  padding: 8px 12px;
  font-size: 0.82rem;
  font-weight: 700;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--brand-strong);
  background: rgba(127, 214, 255, 0.12);
  border: 1px solid rgba(127, 214, 255, 0.22);
}

.game-app {
  display: grid;
  gap: 18px;
}

.stack-block { display: none; }
.stack-block.active,
.stack-block:not([hidden]) { display: block; }

.board-grid {
  display: grid;
  gap: 18px;
  grid-template-columns: repeat(2, minmax(0, 1fr));
}

.compact-board-grid {
  margin-top: 18px;
}

.section-heading { margin-bottom: 14px; }
.compact-head { margin-bottom: 12px; }

.window-grid {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 12px;
}

.window-cell {
  min-height: 78px;
  display: grid;
  place-items: center;
  text-align: center;
  transition: border-color 0.15s ease, background 0.15s ease, transform 0.15s ease;
}

.window-cell.is-lit {
  background: linear-gradient(180deg, rgba(255, 215, 130, 0.22), rgba(127, 214, 255, 0.08));
  border-color: rgba(255, 215, 130, 0.28);
  box-shadow: inset 0 0 0 1px rgba(255, 215, 130, 0.16);
}

.window-cell.is-dark {
  background: linear-gradient(180deg, rgba(255,255,255,0.04), rgba(255,255,255,0.02));
}

.window-cell.is-matching {
  border-color: rgba(127, 214, 255, 0.42);
}

.window-cell span {
  font-size: 0.85rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
}

.target-panel .window-cell.is-lit,
.is-static .window-cell.is-lit {
  background: linear-gradient(180deg, rgba(157, 140, 255, 0.24), rgba(127, 214, 255, 0.08));
  border-color: rgba(157, 140, 255, 0.3);
}

.cue-grid {
  display: grid;
  gap: 12px;
  grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
}

.cue-card {
  display: grid;
  gap: 8px;
  padding: 16px;
  border: 1px solid var(--line);
  background: rgba(255, 255, 255, 0.02);
  cursor: pointer;
  transition: transform 0.15s ease, border-color 0.15s ease, background 0.15s ease;
  text-align: left;
  color: var(--ink);
}

.cue-card:hover:not(:disabled) {
  transform: translateY(-1px);
  border-color: rgba(127, 214, 255, 0.42);
  background: rgba(127, 214, 255, 0.08);
}

.cue-card strong { font-size: 1rem; }
.cue-card span { font-size: 0.92rem; color: var(--ink); }
.cue-card p { margin: 0; font-size: 0.92rem; }

.cue-card.is-used,
.cue-card:disabled {
  cursor: not-allowed;
  opacity: 0.56;
  background: rgba(255, 255, 255, 0.03);
}

.primary-button,
.ghost-button {
  appearance: none;
  border: 0;
  cursor: pointer;
  font: inherit;
  padding: 14px 18px;
  transition: transform 0.15s ease, filter 0.15s ease, background 0.15s ease;
}

.primary-button {
  color: #06111a;
  font-weight: 800;
  background: linear-gradient(135deg, #e1f8ff, #7fd6ff);
  box-shadow: 0 14px 30px rgba(127, 214, 255, 0.22);
}

.ghost-button {
  color: var(--ink);
  background: rgba(255, 255, 255, 0.04);
  border: 1px solid var(--line);
}

.compact-button { padding-inline: 14px; }

.primary-button:hover,
.ghost-button:hover {
  transform: translateY(-1px);
  filter: brightness(1.03);
  text-decoration: none;
}

.feedback-box { min-height: 70px; }

.feedback-card {
  padding: 16px;
  border: 1px solid var(--line);
  background: rgba(255, 255, 255, 0.03);
}

.feedback-card.info {
  border-color: rgba(127, 214, 255, 0.26);
  background: rgba(127, 214, 255, 0.08);
}

.feedback-title {
  margin: 0 0 8px;
  font-weight: 800;
  color: var(--ink);
}

.summary-list {
  display: grid;
  gap: 12px;
  margin-top: 18px;
}

code {
  font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, 'Liberation Mono', monospace;
  background: rgba(255,255,255,0.06);
  padding: 2px 6px;
  border-radius: 8px;
}

@media (max-width: 900px) {
  .hero-panel,
  .board-grid { grid-template-columns: 1fr; }
  .site-header,
  .site-footer,
  .panel-head,
  .progress-row { flex-direction: column; align-items: flex-start; }
}

@media (max-width: 640px) {
  .site-shell { width: min(100% - 20px, 1120px); padding-top: 16px; }
  .card,
  .notice-panel,
  .content-panel,
  .copy-panel,
  .game-panel { padding: 18px; }
  .hero-stats,
  .summary-metrics,
  .legend-grid,
  .cue-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .window-cell { min-height: 60px; padding: 10px; }
  h1 { font-size: 2.05rem; }
}