#chessboard {
    width: 480px;
    height: 480px;
    display: grid;
    grid-template-columns: repeat(8, 1fr);
    grid-template-rows: repeat(8, 1fr);
    border: 3px solid var(--dark-color);
    box-shadow: 0 5px 15px rgba(0, 0, 0, 0.2);
}

.square {
    width: 60px;
    height: 60px;
    display: flex;
    justify-content: center;
    align-items: center;
    position: relative;
}

.light {
    background-color: #f0d9b5;
}

.dark {
    background-color: #b58863;
}

.square.selected {
    background-color: rgba(106, 159, 181, 0.5);
}

.square.highlight {
    position: relative;
}

.square.highlight::before {
    content: '';
    position: absolute;
    width: 20px;
    height: 20px;
    background-color: rgba(106, 159, 181, 0.5);
    border-radius: 50%;
    z-index: 1;
}

.square.last-move {
    background-color: rgba(255, 255, 0, 0.3);
}

.chess-piece {
    width: 50px;
    height: 50px;
    background-size: contain;
    background-repeat: no-repeat;
    background-position: center;
    z-index: 2;
    cursor: pointer;
    transition: transform 0.2s;
}

.chess-piece:hover {
    transform: scale(1.1);
}

/* 棋子样式 */
.piece-wP { background-image: url('../images/wP.svg'); }
.piece-wR { background-image: url('../images/wR.svg'); }
.piece-wN { background-image: url('../images/wN.svg'); }
.piece-wB { background-image: url('../images/wB.svg'); }
.piece-wQ { background-image: url('../images/wQ.svg'); }
.piece-wK { background-image: url('../images/wK.svg'); }

.piece-bP { background-image: url('../images/bP.svg'); }
.piece-bR { background-image: url('../images/bR.svg'); }
.piece-bN { background-image: url('../images/bN.svg'); }
.piece-bB { background-image: url('../images/bB.svg'); }
.piece-bQ { background-image: url('../images/bQ.svg'); }
.piece-bK { background-image: url('../images/bK.svg'); }

/* 升变棋子样式 */
.promotion-pieces .queen.piece { background-image: url('../images/wQ.svg'); }
.promotion-pieces .rook.piece { background-image: url('../images/wR.svg'); }
.promotion-pieces .bishop.piece { background-image: url('../images/wB.svg'); }
.promotion-pieces .knight.piece { background-image: url('../images/wN.svg'); }

@media (max-width: 768px) {
    #chessboard {
        width: 320px;
        height: 320px;
    }
    
    .square {
        width: 40px;
        height: 40px;
    }
    
    .chess-piece {
        width: 35px;
        height: 35px;
    }
}