:root {
  color-scheme: dark;
  --bg: #08111f;
  --panel: rgba(9, 20, 38, 0.82);
  --panel-strong: rgba(14, 28, 50, 0.95);
  --line: rgba(164, 193, 255, 0.18);
  --text: #ecf4ff;
  --muted: #9eb6d6;
  --accent: #8a7dff;
  --accent-2: #3dd7c8;
  --good: #7cf29a;
  --bad: #ff8d8d;
  --shadow: 0 24px 60px rgba(0, 0, 0, 0.35);
}

* { box-sizing: border-box; }
body {
  margin: 0;
  min-height: 100vh;
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  background:
    radial-gradient(circle at top, rgba(84, 119, 255, 0.24), transparent 32%),
    linear-gradient(180deg, #091324, #050b15 65%);
  color: var(--text);
}
button, select {
  font: inherit;
}
button {
  border: 1px solid rgba(177, 197, 255, 0.18);
  background: rgba(255, 255, 255, 0.05);
  color: var(--text);
  border-radius: 14px;
  padding: 0.8rem 1rem;
}
button:hover { background: rgba(255,255,255,0.1); }
button.primary {
  background: linear-gradient(135deg, var(--accent), #5ac8ff);
  color: white;
  border: none;
}
button.ghost { background: transparent; }
select {
  width: 100%;
  border-radius: 12px;
  border: 1px solid var(--line);
  background: rgba(6, 16, 32, 0.95);
  color: var(--text);
  padding: 0.75rem;
}
.shell {
  width: min(1100px, calc(100% - 1.2rem));
  margin: 0 auto;
  padding: 1rem 0 2rem;
}
.topnav {
  display: flex;
  justify-content: center;
  gap: 0.65rem;
  color: var(--muted);
  margin: 0.5rem 0 1rem;
}
.topnav a { color: inherit; text-decoration: none; }
.panel {
  background: var(--panel);
  border: 1px solid var(--line);
  box-shadow: var(--shadow);
  border-radius: 24px;
  backdrop-filter: blur(14px);
}
.hero {
  padding: 1.35rem;
  text-align: center;
}
.eyebrow, .mini, .label { text-transform: uppercase; letter-spacing: 0.14em; color: var(--accent-2); font-size: 0.74rem; }
.subtitle, .hint, .small, .rules li { color: var(--muted); }
.hud {
  margin: 1rem 0;
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 0.75rem;
}
.hud .panel { padding: 0.9rem 1rem; }
.hud span { display: block; color: var(--muted); font-size: 0.8rem; margin-bottom: 0.25rem; }
.layout {
  display: grid;
  grid-template-columns: minmax(0, 1.7fr) minmax(280px, 0.9fr);
  gap: 1rem;
}
.board-panel, .side .panel { padding: 1rem; }
.board-head, .button-row { display: flex; gap: 0.75rem; align-items: center; justify-content: space-between; }
.button-row { flex-wrap: wrap; }
.timeline-block { margin-top: 1rem; }
.beat-row {
  display: grid;
  grid-template-columns: repeat(8, minmax(0, 1fr));
  gap: 0.55rem;
  margin-top: 0.45rem;
}
.beat {
  aspect-ratio: 1;
  border-radius: 18px;
  border: 1px solid rgba(171, 197, 255, 0.16);
  background: rgba(9, 18, 35, 0.86);
  display: grid;
  place-items: center;
  position: relative;
  overflow: hidden;
}
.beat::after {
  content: attr(data-beat);
  position: absolute;
  top: 0.4rem;
  left: 0.55rem;
  font-size: 0.72rem;
  color: rgba(206, 222, 255, 0.5);
}
.beat.active {
  background: linear-gradient(180deg, rgba(138, 125, 255, 0.35), rgba(61, 215, 200, 0.22));
  border-color: rgba(138, 125, 255, 0.5);
}
.beat.pulse { box-shadow: inset 0 0 0 2px rgba(255,255,255,0.16), 0 0 18px rgba(138,125,255,0.45); }
.beat.match { outline: 2px solid rgba(124, 242, 154, 0.75); }
.beat.miss { outline: 2px solid rgba(255, 141, 141, 0.75); }
.stones {
  margin-top: 1.25rem;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 0.9rem;
}
.stone {
  background: var(--panel-strong);
  border: 1px solid rgba(154, 185, 255, 0.14);
  border-radius: 20px;
  padding: 0.9rem;
}
.stone header { display: flex; justify-content: space-between; align-items: center; margin-bottom: 0.6rem; }
.stone-title { font-weight: 700; }
.stone-preview {
  display: grid;
  grid-template-columns: repeat(8, minmax(0, 1fr));
  gap: 0.3rem;
  margin-top: 0.75rem;
}
.stone-preview span {
  height: 0.5rem;
  border-radius: 999px;
  background: rgba(140, 160, 190, 0.2);
}
.stone-preview span.on { background: linear-gradient(90deg, #8a7dff, #3dd7c8); }
.side { display: grid; gap: 1rem; }
.rules ul { padding-left: 1.1rem; margin: 0.6rem 0 0; }
.button-stack { display: grid; gap: 0.6rem; }
.level-dots {
  display: grid;
  grid-template-columns: repeat(6, 1fr);
  gap: 0.45rem;
  list-style: none;
  padding: 0;
  margin: 0.8rem 0;
}
.level-dots li {
  height: 0.72rem;
  border-radius: 999px;
  background: rgba(122, 148, 194, 0.18);
}
.level-dots li.done { background: linear-gradient(90deg, #8a7dff, #3dd7c8); }
.level-dots li.perfect { box-shadow: 0 0 0 2px rgba(124,242,154,0.45) inset; }
@media (max-width: 820px) {
  .hud, .layout, .stones { grid-template-columns: 1fr; }
  .board-head { align-items: flex-start; flex-direction: column; }
}