.ck-board {
  display: grid;
  grid-template-columns: repeat(8, 1fr);
  grid-template-rows: repeat(8, 1fr);
  width: min(96vw, 62vh, 560px);
  aspect-ratio: 1;
  background: var(--card);
  border: 3px solid #1e3a8a;
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  overflow: hidden;
  user-select: none;
  /* `none` (not `manipulation`) so a touch-drag on a piece doesn't scroll the
     page — required for the shared drag-and-drop helper to fire pointermove. */
  touch-action: none;
}

.ck-sq { min-width: 0; min-height: 0; }

.ck-sq {
  position: relative;
  display: flex;
  align-items: center;
  justify-content: center;
  background: #f8fafc;
  border: none;
  padding: 0;
  cursor: default;
}

.ck-sq.dark {
  background: #1e3a8a;
  cursor: pointer;
}

.ck-sq.selected { outline: 3px solid #f59e0b; outline-offset: -3px; z-index: 2; }
.ck-sq.hint::after {
  content: "";
  position: absolute;
  width: 30%;
  height: 30%;
  background: rgba(16, 185, 129, 0.85);
  border-radius: 50%;
}

.ck-piece {
  width: 70%;
  height: 70%;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 800;
  color: rgba(255, 255, 255, 0.9);
  box-shadow: inset 0 -4px 0 rgba(0, 0, 0, 0.25), 0 2px 6px rgba(0, 0, 0, 0.3);
}

.ck-piece.red { background: linear-gradient(135deg, #ef4444, #b91c1c); }
.ck-piece.black { background: linear-gradient(135deg, #111827, #000); color: #fef3c7; }
.ck-piece.king::after {
  content: "♔";
  font-size: clamp(18px, 4vw, 28px);
}