:root {
  --bg: #f0f0f0;
  --panel-bg: #d9d9d9;
  --text: #222;
  --cell-hidden: #b0b0b0;
  --cell-hidden-hover: #c2c2c2;
  --cell-revealed: #e0e0e0;
  --cell-border: #888;
  --accent: #4a90d9;
  --modal-bg: #ffffff;
  --overlay: rgba(0, 0, 0, 0.5);
}

body.dark {
  --bg: #1e1e1e;
  --panel-bg: #2a2a2a;
  --text: #eee;
  --cell-hidden: #3c3c3c;
  --cell-hidden-hover: #4a4a4a;
  --cell-revealed: #2f2f2f;
  --cell-border: #555;
  --accent: #6aa9e9;
  --modal-bg: #2a2a2a;
  --overlay: rgba(0, 0, 0, 0.7);
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  background: var(--bg);
  color: var(--text);
  font-family: "Segoe UI", "Malgun Gothic", sans-serif;
  transition: background 0.2s, color 0.2s;
}

.app {
  max-width: 720px;
  margin: 0 auto;
  padding: 16px;
}

.app-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 12px;
}

.app-header h1 {
  font-size: 1.4rem;
  margin: 0;
}

.header-controls {
  display: flex;
  gap: 8px;
  align-items: center;
}

select,
button {
  font-size: 1rem;
  padding: 6px 10px;
  border-radius: 6px;
  border: 1px solid var(--cell-border);
  background: var(--panel-bg);
  color: var(--text);
  cursor: pointer;
}

.status-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  background: var(--panel-bg);
  border-radius: 8px;
  padding: 8px 16px;
  margin-bottom: 8px;
  font-variant-numeric: tabular-nums;
  font-weight: bold;
}

#new-game-btn {
  font-size: 1.4rem;
  line-height: 1;
  padding: 4px 10px;
}

.best-time {
  text-align: center;
  margin-bottom: 12px;
  font-size: 0.9rem;
  opacity: 0.8;
}

.board {
  display: grid;
  grid-template-columns: repeat(var(--cols), 1fr);
  gap: 2px;
  width: min(100%, calc(var(--cols) * 32px));
  margin: 0 auto;
  background: var(--cell-border);
  padding: 2px;
  border-radius: 6px;
}

.cell {
  aspect-ratio: 1 / 1;
  width: 100%;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--cell-hidden);
  border: none;
  border-radius: 2px;
  font-size: 0.9rem;
  font-weight: bold;
  padding: 0;
  cursor: pointer;
  user-select: none;
}

.cell:hover:not(.revealed) {
  background: var(--cell-hidden-hover);
}

.cell.revealed {
  background: var(--cell-revealed);
  cursor: default;
}

.cell.mine {
  background: #e05a5a;
}

.cell.mine.exploded {
  background: #ff2d2d;
}

.cell.wrong-flag {
  background: #e0b05a;
}

.cell.n1 { color: #2255dd; }
.cell.n2 { color: #2f8f2f; }
.cell.n3 { color: #d92f2f; }
.cell.n4 { color: #16277a; }
.cell.n5 { color: #7a1616; }
.cell.n6 { color: #1a8f8f; }
.cell.n7 { color: #222; }
.cell.n8 { color: #666; }

body.dark .cell.n7 { color: #eee; }

.modal {
  position: fixed;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--overlay);
}

.modal.hidden {
  display: none;
}

.modal-content {
  background: var(--modal-bg);
  color: var(--text);
  padding: 24px 32px;
  border-radius: 10px;
  text-align: center;
  min-width: 240px;
}

.modal-content h2 {
  margin-top: 0;
}

@media (max-width: 480px) {
  .app-header h1 {
    font-size: 1.1rem;
  }

  .cell {
    font-size: 0.75rem;
  }
}