.board {
  width: min(430px, 60%);
  position: relative;
  grid-template-columns: repeat(8, minmax(0, 1fr));
  grid-template-rows: repeat(8, minmax(0, 1fr));
  box-shadow: 0 7px 23px #12241c2b;
}

.square {
  position: relative;
  z-index: 1;
  width: 100%;
  height: 100%;
  min-width: 0;
  min-height: 0;
  aspect-ratio: 1;
  overflow: hidden;
}

.engine-arrows { position:absolute; inset:0; z-index:2; width:100%; height:100%; pointer-events:none; overflow:visible; }
.engine-arrow { fill:none; stroke:#c9e765; stroke-linecap:butt; stroke-width:2.4; }
.engine-arrowhead { fill:#c9e765; }

.piece {
  display: block;
  width: 94%;
  height: 94%;
  object-fit: contain;
  filter: drop-shadow(0 1px 1px #17201e2a);
  transition: opacity 120ms ease, filter 120ms ease, transform 120ms ease;
}

#board.is-engine-preview .piece {
  opacity: .46;
  filter: grayscale(.18) saturate(.72) drop-shadow(0 1px 1px #17201e1f);
  transform: scale(.96);
}

#board.is-engine-preview {
  box-shadow: inset 0 0 0 3px color-mix(in srgb, #c9e765 58%, transparent);
}

.square.last-from,
.square.last-to {
  box-shadow: inset 0 0 0 3px #c9e765;
}

.square.last-to {
  box-shadow: inset 0 0 0 3px #1e5c4d;
}

@media (max-width: 700px) {
  .board {
    width: min(100%, 430px);
  }
}