:root{
  --bg:#171321;
  --fg:#f7f8fa;
  --accent:#ABF500;
  --muted:#235FA8;
  --tile:#0d314b;
  --tileHi:#143d5d;
  --shadow:0 10px 30px rgba(0,0,0,.35);
}
[hidden] { display: none !important; }
*{box-sizing:border-box}
html,body{height:100%;margin:0}
body{
  font-family:Poppins,system-ui,-apple-system,Segoe UI,Roboto,Ubuntu,"Helvetica Neue",Arial;
  background:var(--bg); color:var(--fg); display:flex; flex-direction:column; align-items:center;
}
.bar{width:min(1100px,95%); display:flex; justify-content:space-between; align-items:center; gap:1rem; padding:1rem 0;}
h1{margin:0; font-size:1.25rem}
.hud{display:flex; gap:.75rem; align-items:center; flex-wrap:wrap}
button{
  background:var(--muted); color:#fff; border:none; padding:.5rem .75rem; border-radius:.5rem;
  cursor:pointer; transition:transform .15s ease, background .2s ease;
}
button:hover{transform:translateY(-1px); background:#2e74c8}
select{background:#10263a; color:#fff; border:1px solid #274d76; border-radius:.35rem; padding:.25rem .5rem}

main{width:min(1100px,95%); display:grid; place-items:center}
.grid{
  width:min(95vmin, 900px);
  display:grid;
  gap:10px;
  padding:10px;
}
.grid[data-cols="4"]{ grid-template-columns: repeat(4, 1fr); }
.grid[data-cols="5"]{ grid-template-columns: repeat(5, 1fr); }
.grid[data-cols="6"]{ grid-template-columns: repeat(6, 1fr); }

.card{
  position:relative;
  aspect-ratio: 1 / 1;
  border-radius:14px;
  box-shadow:var(--shadow);
  perspective:1000px;
  outline:none;
}
.card .face{
  position:absolute; inset:0;
  display:grid; place-items:center;
  border-radius:14px;
  backface-visibility:hidden;
  transition:transform .36s ease;
  font-size: clamp(24px, 6vmin, 64px);
}
.card .front{
  background:linear-gradient(145deg, var(--tile), var(--tileHi));
  border:2px solid rgba(255,255,255,.08);
}
.card .back{
  transform:rotateY(180deg);
  background:#082133;
  border:2px solid rgba(255,255,255,.1);
}
.card.revealed .front{ transform:rotateY(180deg); }
.card.revealed .back{ transform:rotateY(0deg); }
.card.matched{ outline:2px solid var(--accent); box-shadow:0 0 0 3px rgba(171,245,0,.4), var(--shadow); }

.hint{opacity:.85; padding:1rem; text-align:center}
.overlay{
  position:fixed; inset:0; display:grid; place-items:center;
  background:rgba(0,0,0,.5);
  z-index: 1000;
}
.modal{
  background:#0d314b; color:#fff; border:2px solid var(--accent);
  border-radius:16px; padding:1.25rem 1.5rem; width:min(420px, 92%); text-align:center; box-shadow:var(--shadow);
}
.modal h2{margin-top:0}

@media (max-width: 520px) {
  .bar{flex-direction:column; align-items:flex-start}
}