/* Sliding Puzzle — 3×3 / 4×4 / 5×5 grid */

.sp-board {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 0.45rem;
  width: 100%;
  max-width: 340px;
  aspect-ratio: 1;
  padding: 0.55rem;
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  user-select: none;
  touch-action: manipulation;
}
.sp-board[data-n="3"] { grid-template-columns: repeat(3, 1fr); max-width: 300px; }
.sp-board[data-n="4"] { grid-template-columns: repeat(4, 1fr); max-width: 340px; }
.sp-board[data-n="5"] { grid-template-columns: repeat(5, 1fr); max-width: 360px; gap: 0.35rem; padding: 0.45rem; }

.sp-tile {
  display: flex;
  align-items: center;
  justify-content: center;
  min-width: 44px;
  min-height: 44px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border-color);
  background: var(--bg-surface);
  color: var(--text-primary);
  font-family: var(--font-mono);
  font-size: clamp(1rem, 3.6cqi, 1.35rem);
  font-weight: 700;
  cursor: pointer;
  box-shadow: var(--shadow-xs);
  transition: transform 90ms var(--ease-out), background 120ms var(--ease-out), border-color 120ms var(--ease-out), color 120ms var(--ease-out);
  padding: 0;
}
.sp-board[data-n="5"] .sp-tile {
  font-size: clamp(0.875rem, 3cqi, 1.1rem);
}
.sp-tile:hover:not(.is-gap) {
  border-color: var(--brand-primary);
  transform: translateY(-1px);
}
.sp-tile:focus-visible {
  outline: 2px solid var(--brand-primary);
  outline-offset: -2px;
}
.sp-tile.is-home {
  background: var(--brand-subtle);
  border-color: var(--brand-border);
  color: var(--brand-primary);
}
.sp-tile.is-gap {
  background: transparent;
  border-color: transparent;
  box-shadow: none;
  cursor: default;
  pointer-events: none;
}

@container (max-width: 400px) {
  .sp-board[data-n="5"] { gap: 0.25rem; padding: 0.35rem; }
}