/* Opponent moves use the same yellow highlight as the player's last move. */
#puzzle-board-surface-26.opponent-last-move .cg-board square.last-move,
.puzzle-board.opponent-last-move .cg-board square.last-move {
    background-color: rgba(155, 199, 0, 0.41);
}

/* Keep check clearly visible even when the checked square is also highlighted. */
#puzzle-board-surface-26 .cg-board square.check,
.puzzle-board .cg-board square.check {
    background: radial-gradient(
        ellipse at center,
        rgba(255, 70, 70, 0.96) 0%,
        rgba(220, 35, 35, 0.82) 38%,
        rgba(169, 0, 0, 0.18) 70%,
        rgba(158, 0, 0, 0) 100%
    );
}