:root {
  --bg: #0f1419;
  --sidebar: #1a2332;
  --text: #e7ecf3;
  --muted: #8b9cb3;
  --accent: #3d8bfd;
  --accent-hover: #5a9dff;
  --cell-hidden: #2a3544;
  --cell-safe: #243d2e;
  --cell-mine: #5c2a32;
  --border: #2f3d4d;
  --balance-main: #7dffb3;
  --balance-main-glow: rgba(125, 255, 179, 0.35);
  --radius: 8px;
  font-family: system-ui, Segoe UI, Roboto, sans-serif;
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  background: var(--bg);
  color: var(--text);
}

.app {
  display: flex;
  min-height: 100vh;
}

.sidebar {
  width: 280px;
  flex-shrink: 0;
  padding: 1.25rem 1.5rem;
  background: var(--sidebar);
  border-right: 1px solid var(--border);
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.title {
  margin: 0;
  font-size: 1.35rem;
  font-weight: 600;
}

.field {
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
}

.label {
  font-size: 0.85rem;
  color: var(--muted);
}

input[type="number"] {
  width: 100%;
  padding: 0.5rem 0.65rem;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--bg);
  color: var(--text);
  font-size: 1rem;
}

input[type="number"][readonly],
input[type="number"]:read-only {
  background: #151c26;
  color: var(--muted);
  cursor: default;
}

input[type="number"]:disabled {
  opacity: 0.55;
  cursor: not-allowed;
}

.btn {
  padding: 0.6rem 1rem;
  border-radius: var(--radius);
  border: 1px solid var(--border);
  background: var(--cell-hidden);
  color: var(--text);
  font-size: 1rem;
  cursor: pointer;
}

.btn.primary {
  background: var(--accent);
  border-color: var(--accent);
  font-weight: 600;
}

.btn.primary:hover:not(:disabled) {
  background: var(--accent-hover);
  border-color: var(--accent-hover);
}

.btn:disabled {
  opacity: 0.45;
  cursor: not-allowed;
}

.status {
  margin: 0;
  font-size: 0.9rem;
  color: var(--muted);
  line-height: 1.4;
}

.main {
  position: relative;
  flex: 1;
  min-width: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 1rem;
}

.main-stack {
  display: flex;
  flex-direction: column;
  align-items: center;
  width: 100%;
  max-width: min(100%, 900px);
}

.main-balance {
  position: absolute;
  top: 1rem;
  right: 1rem;
  margin: 0 0 0.75rem 0;
  z-index: 1;
  max-width: calc(100% - 2rem);
  text-align: right;
  font-size: clamp(1.75rem, 4vw, 2.5rem);
  font-weight: 700;
  letter-spacing: 0.02em;
  color: var(--balance-main);
  text-shadow: 0 0 24px var(--balance-main-glow), 0 0 2px rgba(0, 0, 0, 0.8);
}

.board-wrap {
  width: min(100%, min(85vh, 900px));
  aspect-ratio: 1 / 1;
  max-height: 85vh;
}

.board {
  display: grid;
  width: 100%;
  height: 100%;
  gap: 4px;
  padding: 4px;
  background: var(--border);
  border-radius: var(--radius);
}

.board.is-idle .cell {
  opacity: 0.5;
  pointer-events: none;
}

.cell {
  min-width: 0;
  min-height: 0;
  border: none;
  border-radius: 4px;
  background: var(--cell-hidden);
  color: var(--text);
  font-size: clamp(0.65rem, 2.5vmin, 1rem);
  font-weight: 600;
  cursor: pointer;
  transition: background 0.12s ease, transform 0.08s ease;
}

.cell:hover:not(:disabled) {
  filter: brightness(1.08);
}

.cell:active:not(:disabled) {
  transform: scale(0.97);
}

.cell:disabled {
  cursor: default;
}

.cell.revealed.safe {
  background: var(--cell-safe);
  color: #a8d4b4;
}

.cell.revealed.mine {
  background: var(--cell-mine);
  color: #ffb4bc;
}

@media (max-width: 720px) {
  .app {
    flex-direction: column;
  }

  .sidebar {
    width: 100%;
    border-right: none;
    border-bottom: 1px solid var(--border);
  }

  .board-wrap {
    width: min(100%, 70vh);
  }
}