board.css

:root {
    --board-bg-color: rgb(255, 233, 200);
    --next-piece: url(cross.svg);
}

.cell {
    width: 4vw;
    aspect-ratio: 1;
    cursor: pointer;
    background-color: var(--board-bg-color);
    background-size: cover;
}

.cell:hover {
    background-color: #ebcaff;
    background-image: var(--next-piece);
}

.small-board[data-placeable="true"] {
    background-color: #a8fac7;
}

.small-board {
    background-color: var(--board-bg-color);
    padding: 0.5vw;
    aspect-ratio: 1; 
    position: relative;   
}

.small-board-grid {
    width: min-content;
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    grid-template-rows: repeat(3, 1fr);
    column-gap: 0.25vw;
    row-gap: 0.25vw;
    background-color: black;
}


.big-board {
    padding: 0.5vw;
    aspect-ratio: 1;
    width: min-content;
    background-color: var(--board-bg-color);
    border-radius: 1vw; 
}

.big-board-grid {
    display: grid;
    width: min-content;
    grid-template-columns: repeat(3, 1fr);
    grid-template-rows: repeat(3, 1fr);
    column-gap: 0.5vw;
    row-gap: 0.5vw;
    background-color: black;
}

.winner-overlay {
    width: 100%;
    height: 100%;
    position: absolute;
    top: 0;
    left: 0;
    pointer-events: none;
    background-size: cover;
}

.cell[data-content="o"] {
    background-image: url(nought.svg);
    pointer-events: none;
}

.cell[data-content="x"] {
    background-image: url(cross.svg);
    pointer-events: none;
}


.small-board:not([data-content=""]) .small-board-grid {
    filter: blur(3px);
    opacity: 0.8;
    pointer-events: none;
}

.small-board[data-content="x"] .winner-overlay {
    background-image: url(cross.svg);
}

.small-board[data-content="o"] .winner-overlay {
    background-image: url(nought.svg);
}

.small-board:not([data-content=""]) .cell {
    pointer-events: none;
}

.small-board[data-placeable="false"] .cell {
    pointer-events: none;
}