.ch-board {
  display: grid;
  grid-template-columns: repeat(8, 1fr);
  width: min(440px, 100%);
  aspect-ratio: 1;
  border-radius: 6px;
  overflow: hidden;
  border: 3px solid #3e2a1e;
}

.ch-sq {
  display: flex;
  align-items: center;
  justify-content: center;
  border: none;
  padding: 0;
  position: relative;
  font-size: clamp(1.4rem, 5vw, 2rem);
  cursor: pointer;
}

.ch-sq.ch-light { background: #e8d3ae; }
.ch-sq.ch-dark { background: #6b4a32; }
.ch-sq.ch-selected { box-shadow: inset 0 0 0 3px var(--color-primary); }
.ch-sq.ch-in-check { box-shadow: inset 0 0 0 3px #ff4d4d; }
.ch-sq.ch-target::after {
  content: "";
  position: absolute;
  width: 26%;
  height: 26%;
  border-radius: 50%;
  background: rgba(79,216,224,0.6);
}
.ch-sq.ch-target-capture { box-shadow: inset 0 0 0 3px var(--color-accent); }

.ch-piece-w { color: #f7f3e8; text-shadow: 0 1px 2px rgba(0,0,0,0.7); }
.ch-piece-b { color: #171717; text-shadow: 0 1px 1px rgba(255,255,255,0.25); }