:root {
  --bg: #0d1b2a;
  --bg2: #1b263b;
  --glass: #e0e4ea;
  --edgeLight: #ffffff;
  --edgeDark: #7b8794;
  --tileFace: #cfd6df;
  --text: #e8eef8;
}
* { box-sizing: border-box; }
body {
  margin: 0;
  min-height: 100vh;
  font-family: Tahoma, Verdana, Segoe UI, sans-serif;
  color: var(--text);
  background:
    radial-gradient(circle at 10% 20%, #304c89 0%, transparent 45%),
    radial-gradient(circle at 90% 0%, #3d5a80 0%, transparent 35%),
    linear-gradient(160deg, var(--bg), var(--bg2));
  display: grid;
  place-items: center;
  padding: 16px;
}
.game-shell {
  width: min(96vw, 980px);
  background: #aeb7c4;
  border: 3px solid;
  border-color: var(--edgeLight) var(--edgeDark) var(--edgeDark) var(--edgeLight);
  box-shadow: 0 25px 45px rgba(0,0,0,.35);
  padding: 12px;
}
.topbar {
  background: #9aa5b3;
  border: 3px solid;
  border-color: var(--edgeDark) var(--edgeLight) var(--edgeLight) var(--edgeDark);
  padding: 10px;
  display: flex;
  justify-content: space-between;
  align-items: center;
}
.counter {
  font-family: 'Courier New', monospace;
  background: #1a1a1a;
  color: #ff3b30;
  font-size: 2rem;
  padding: 4px 10px;
  min-width: 90px;
  text-align: center;
  border: 2px inset #666;
}
.face {
  border: 3px solid;
  border-color: var(--edgeLight) var(--edgeDark) var(--edgeDark) var(--edgeLight);
  background: var(--tileFace);
  font-size: 1.5rem;
  cursor: pointer;
  padding: 6px 10px;
}
.panel {
  margin-top: 10px;
  display: flex;
  gap: 10px;
  flex-wrap: wrap;
  align-items: center;
  color: #10243f;
}
.panel select, .panel button {
  margin-left: 6px;
  background: #dde3ea;
  border: 2px solid;
  border-color: var(--edgeLight) var(--edgeDark) var(--edgeDark) var(--edgeLight);
  padding: 6px 10px;
}
.board-wrap {
  margin-top: 12px;
  overflow: auto;
  background: #8f9bac;
  border: 3px solid;
  border-color: var(--edgeDark) var(--edgeLight) var(--edgeLight) var(--edgeDark);
  padding: 14px;
}
.board {
  display: grid;
  gap: 2px;
  width: max-content;
  margin: 8px auto;
  filter: drop-shadow(0 10px 8px rgba(0,0,0,.25));
}
.cell {
  width: 30px;
  height: 30px;
  user-select: none;
  cursor: pointer;
  position: relative;
  transform-style: preserve-3d;
}
.cell-btn {
  width: 100%;
  height: 100%;
  border: none;
  padding: 0;
  font: bold 20px/1 Tahoma, sans-serif;
  color: #09172b;
  background: var(--tileFace);
  box-shadow:
    inset 2px 2px 0 var(--edgeLight),
    inset -2px -2px 0 var(--edgeDark),
    0 4px 0 #7c8794;
}
.cell.open .cell-btn {
  background: #b5becb;
  box-shadow: inset 1px 1px 0 #7f8b98, inset -1px -1px 0 #d7dde6;
}
.cell.mine .cell-btn { background: #ff8a80; }
.n1 { color: #1d4ed8; } .n2 { color: #047857; } .n3 { color: #dc2626; }
.n4 { color: #312e81; } .n5 { color: #7c2d12; } .n6 { color: #0f766e; }
.n7 { color: #111827; } .n8 { color: #6b7280; }
.hint {
  margin: 10px 0 0;
  color: #10243f;
  font-size: .95rem;
}
@media (max-width: 740px) {
  .cell { width: 24px; height: 24px; }
  .cell-btn { font-size: 16px; }
  .counter { font-size: 1.5rem; min-width: 74px; }
}