* { box-sizing: border-box; }
:root {
  --bg: #0b0e14;
  --panel: #111827;
  --muted: #9CA3AF;
  --accent: #22d3ee;
  --card: #1f2937;
  --win: #22c55e;
  --shadow: 0 10px 25px rgba(0,0,0,0.35);
  --cell: 80px;    /* updated at runtime */
  --fs: 36px;      /* updated at runtime */
  --gap: .6rem;
}

html, body {
  margin: 0;
  height: 100%;
  background: radial-gradient(1200px 800px at 20% 0%, #0b1220 0%, #0b0e14 45%, #06080d 100%);
  color: #e5e7eb;
  font-family: system-ui, -apple-system, Segoe UI, Roboto, Helvetica, Arial, "Apple Color Emoji","Segoe UI Emoji";
}

.topbar {
  position: sticky; top: 0; z-index: 5;
  backdrop-filter: blur(6px);
  background: rgba(11,14,20,0.6);
  border-bottom: 1px solid rgba(255,255,255,0.06);
  padding: .6rem 1rem;
  display: grid;
  grid-template-columns: 1fr auto;
  align-items: center;
}

.hud { display: flex; gap: .8rem; align-items: center; }
.hud-item {
  background: rgba(255,255,255,0.06);
  border: 1px solid rgba(255,255,255,0.1);
  border-radius: 14px;
  padding: .35rem .8rem;
  display: flex; gap: .6rem; align-items: baseline;
  box-shadow: var(--shadow);
}
.label { color: var(--muted); font-size: .8rem; }
.hint { color: var(--muted); font-size: .9rem; }

main { display: grid; place-items: center; padding: 1rem; }

.grid {
  --cols: 4;
  display: grid;
  grid-template-columns: repeat(var(--cols), var(--cell));
  grid-auto-rows: var(--cell);
  gap: var(--gap);
  width: auto;
  margin: 1rem auto 2rem auto;
  justify-content: center;
}

.card {
  position: relative;
  width: var(--cell);
  height: var(--cell);
  aspect-ratio: 1/1;
  border-radius: 18px;
  background: var(--card);
  border: 1px solid rgba(255,255,255,0.08);
  cursor: pointer;
  transform-style: preserve-3d;
  transition: transform .35s ease;
  box-shadow: var(--shadow);
  user-select: none;
}
.card.flip { transform: rotateY(180deg); }
.card.matched { outline: 3px solid var(--win); }

.face, .back {
  position: absolute; inset: 0;
  display: grid; place-items: center;
  font-size: var(--fs);
  border-radius: 18px;
  backface-visibility: hidden;
}
.face { transform: rotateY(180deg); background: linear-gradient(180deg, rgba(34,211,238,0.12), rgba(34,211,238,0.05)); }
.back { background: linear-gradient(180deg, rgba(255,255,255,0.06), rgba(255,255,255,0.03)); }

.overlay, .scoresheet {
  position: fixed; inset: 0;
  display: grid; place-items: center;
  background: rgba(0,0,0,0.5);
  z-index: 10;
}
.overlay.hidden, .scoresheet.hidden { display: none; }

.panel {
  background: var(--panel);
  border: 1px solid rgba(255,255,255,0.08);
  border-radius: 22px;
  padding: 1.4rem 1.2rem;
  width: min(92vw, 560px);
  text-align: center;
  box-shadow: var(--shadow);
}

.btn {
  background: linear-gradient(180deg, #22d3ee, #0ea5e9);
  color: #06121a;
  font-weight: 700;
  border: none;
  border-radius: 14px;
  padding: .8rem 1.1rem;
  margin: .4rem;
  cursor: pointer;
  box-shadow: var(--shadow);
}
.btn.ghost { background: transparent; color: #e5e7eb; border: 1px solid rgba(255,255,255,0.2); }
.btn:disabled { opacity: .6; cursor: not-allowed; }

.scoresheet .sheet-head, .scoresheet .sheet-foot {
  background: var(--panel);
  border: 1px solid rgba(255,255,255,0.08);
  padding: .8rem 1rem;
  width: min(92vw, 560px);
  border-radius: 18px;
  box-shadow: var(--shadow);
}
.scoresheet .sheet-head { display: flex; align-items: center; justify-content: space-between; }
.icon-btn {
  background: rgba(255,255,255,0.1);
  border: 1px solid rgba(255,255,255,0.2);
  border-radius: 10px;
  padding: .4rem .6rem;
  color: #e5e7eb;
  cursor: pointer;
}
.score-list {
  width: min(92vw, 560px);
  list-style: decimal;
  background: rgba(255,255,255,0.04);
  border: 1px solid rgba(255,255,255,0.08);
  border-radius: 18px;
  padding: .6rem .8rem;
  margin: .8rem 0;
}
.score-list li {
  display: grid;
  grid-template-columns: 1.4fr .8fr .8fr;
  gap: .6rem;
  padding: .4rem .2rem;
  border-bottom: 1px dashed rgba(255,255,255,0.08);
}
.score-list li:last-child { border-bottom: none; }
.score-list .muted { color: var(--muted); font-size: .9rem; }

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

@media (hover: none) and (pointer: coarse) {
  .hint { display: none; }
}