:root {
  --bg: #0d1015;
  --panel: #161b23;
  --panel-2: #1d2430;
  --line: #2b3442;
  --text: #d7dee8;
  --muted: #8b96a5;
  --accent: #4b7fc4;
  --accent-soft: #23334a;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  padding: 0 1.25rem 3rem;
  background: var(--bg);
  color: var(--text);
  font-family: system-ui, -apple-system, "Segoe UI", "Hiragino Sans", "Noto Sans JP", sans-serif;
  line-height: 1.7;
  max-width: 1100px;
  margin-inline: auto;
}

header { padding: 2rem 0 1rem; }

h1 {
  margin: 0;
  font-size: 1.9rem;
  letter-spacing: 0.02em;
}

.tagline {
  margin: 0.5rem 0 0;
  color: var(--muted);
  max-width: 70ch;
}

.tagline strong { color: var(--text); }

nav {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin: 1.25rem 0;
}

nav button {
  background: var(--panel);
  color: var(--text);
  border: 1px solid var(--line);
  border-radius: 999px;
  padding: 0.4rem 0.95rem;
  font: inherit;
  font-size: 0.9rem;
  cursor: pointer;
}

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

nav button[aria-current="true"] {
  background: var(--accent-soft);
  border-color: var(--accent);
}

#stage h2 {
  margin: 0 0 0.25rem;
  font-size: 1.25rem;
}

#demo-summary {
  margin: 0 0 1rem;
  color: var(--muted);
  max-width: 75ch;
}

#canvas-wrap { position: relative; }

canvas {
  display: block;
  width: 100%;
  height: min(60vh, 520px);
  background: #12161d;
  border: 1px solid var(--line);
  border-radius: 10px;
  touch-action: none;
  cursor: crosshair;
}

#hint {
  position: absolute;
  left: 0.9rem;
  bottom: 0.7rem;
  margin: 0;
  font-size: 0.85rem;
  color: var(--muted);
  background: rgba(13, 16, 21, 0.75);
  padding: 0.15rem 0.55rem;
  border-radius: 6px;
  pointer-events: none;
}

#controls {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.6rem 1rem;
  margin: 0.9rem 0;
}

#controls button {
  background: var(--panel-2);
  color: var(--text);
  border: 1px solid var(--line);
  border-radius: 7px;
  padding: 0.35rem 0.85rem;
  font: inherit;
  font-size: 0.9rem;
  cursor: pointer;
}

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

#controls button[aria-pressed="true"] {
  background: var(--accent-soft);
  border-color: var(--accent);
}

#controls label {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 0.9rem;
  color: var(--muted);
}

#controls input[type="range"] { width: 190px; }

.group {
  display: inline-flex;
  gap: 0.35rem;
  padding: 0.2rem;
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: 9px;
}

#readout {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem 2rem;
  margin: 1rem 0 0;
  padding: 0.75rem 1rem;
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: 9px;
}

#readout div { display: flex; gap: 0.6rem; align-items: baseline; }

#readout dt {
  color: var(--muted);
  font-size: 0.82rem;
}

#readout dd {
  margin: 0;
  font-family: ui-monospace, "Cascadia Mono", Consolas, monospace;
  font-size: 0.92rem;
}

.note, footer p {
  color: var(--muted);
  font-size: 0.88rem;
  max-width: 78ch;
}

.note strong { color: var(--text); }

footer {
  margin-top: 2rem;
  padding-top: 1rem;
  border-top: 1px solid var(--line);
}

code {
  font-family: ui-monospace, "Cascadia Mono", Consolas, monospace;
  background: var(--panel);
  padding: 0.1rem 0.35rem;
  border-radius: 4px;
}