:root {
  --bg: #0d1117;
  --surface: #161b22;
  --line: #30363d;
  --ink: #e6edf3;
  --muted: #8b949e;
  --accent: #5e9eff;
  --green: #7ee787;
  --amber: #ffd479;
  --red: #ff7b72;
  --mono: ui-monospace, 'Cascadia Code', 'Segoe UI Mono', Menlo, Consolas, monospace;
  --sans: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: var(--sans);
  -webkit-font-smoothing: antialiased;
}

header {
  max-width: 1180px;
  margin: 0 auto;
  padding: 48px 24px 8px;
}

h1 {
  margin: 0;
  font-size: 30px;
  font-weight: 700;
  letter-spacing: -0.5px;
}

.tagline {
  margin: 10px 0 0;
  max-width: 62ch;
  color: var(--muted);
  font-size: 16px;
  line-height: 1.6;
}

main {
  max-width: 1180px;
  margin: 0 auto;
  padding: 24px;
  display: grid;
  grid-template-columns: minmax(0, 1fr) 296px;
  gap: 24px;
  align-items: start;
}

.stage-wrap {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 14px;
  padding: 12px 12px 8px;
}

canvas {
  display: block;
  width: 100%;
  height: 620px;
  border-radius: 10px;
}

.narration {
  margin: 10px 4px 0;
  font-family: var(--mono);
  font-size: 12.5px;
  color: var(--accent);
  min-height: 1.4em;
}

.hint {
  margin: 4px 4px 6px;
  font-family: var(--mono);
  font-size: 11.5px;
  color: var(--muted);
  opacity: 0.75;
}

.panel {
  display: flex;
  flex-direction: column;
  gap: 18px;
}

.group {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 14px;
  padding: 18px;
}

.group h2 {
  margin: 0 0 14px;
  font-family: var(--mono);
  font-size: 11px;
  font-weight: 600;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--muted);
}

label {
  display: block;
  margin-bottom: 16px;
}

label:last-child {
  margin-bottom: 0;
}

label span {
  display: block;
  margin-bottom: 7px;
  font-size: 12.5px;
  color: var(--muted);
}

label b {
  color: var(--ink);
  font-family: var(--mono);
}

input[type='range'] {
  width: 100%;
  height: 3px;
  appearance: none;
  background: var(--line);
  border-radius: 2px;
  outline: none;
}

input[type='range']::-webkit-slider-thumb {
  appearance: none;
  width: 14px;
  height: 14px;
  border-radius: 50%;
  background: var(--accent);
  cursor: pointer;
  border: 2px solid var(--bg);
}

input[type='range']::-moz-range-thumb {
  width: 14px;
  height: 14px;
  border: 2px solid var(--bg);
  border-radius: 50%;
  background: var(--accent);
  cursor: pointer;
}

.buttons {
  display: flex;
  gap: 10px;
}

button {
  flex: 1;
  padding: 10px 12px;
  border-radius: 999px;
  border: 1px solid var(--line);
  background: transparent;
  color: var(--muted);
  font-family: var(--mono);
  font-size: 12.5px;
  cursor: pointer;
  transition: border-color 0.2s, color 0.2s, opacity 0.2s;
}

button:hover {
  border-color: var(--accent);
  color: var(--accent);
}

button.primary {
  background: var(--accent);
  border-color: var(--accent);
  color: #04101f;
  font-weight: 600;
}

button.primary:hover {
  opacity: 0.86;
  color: #04101f;
}

.stats dl {
  margin: 0;
  display: flex;
  flex-direction: column;
  gap: 9px;
}

.stats dl > div {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  gap: 12px;
}

.stats dt {
  font-size: 12.5px;
  color: var(--muted);
}

.stats dd {
  margin: 0;
  font-family: var(--mono);
  font-size: 13px;
  color: var(--ink);
}

.legend ul {
  margin: 0;
  padding: 0;
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 9px;
  font-size: 12.5px;
  color: var(--muted);
}

.legend li {
  display: flex;
  align-items: center;
  gap: 9px;
}

.dot {
  width: 9px;
  height: 9px;
  border-radius: 50%;
  flex-shrink: 0;
}

.dot.query {
  background: var(--red);
}
.dot.current {
  background: #fff;
}
.dot.visited {
  background: var(--green);
}
.dot.result {
  background: var(--amber);
}

footer {
  max-width: 1180px;
  margin: 0 auto;
  padding: 8px 24px 56px;
}

footer p {
  margin: 0;
  max-width: 70ch;
  font-size: 13px;
  line-height: 1.7;
  color: var(--muted);
}

a {
  color: var(--accent);
  text-decoration: none;
}

a:hover {
  text-decoration: underline;
}

@media (max-width: 900px) {
  main {
    grid-template-columns: minmax(0, 1fr);
  }
  canvas {
    height: 460px;
  }
}