style.css

* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

body {
    height: 100vh;
    width: 100vw;
    background-color: rgb(54, 44, 42);
}

.board {
    display: grid;
    width: 100%;
    height: 100%;
    display: grid;
    justify-content: center;
    align-content: center;
    justify-items: center;
    align-items: center;
    grid-template-columns: repeat(3, auto);
}

/* DEFINE A COR DO HOVER */
.board.x .cell:not(.x):not(.circle):hover::after,
.board.x .cell:not(.x):not(.circle):hover::before,
.board.circle .cell:not(.x):not(.circle):hover::after,
.board.circle .cell:not(.x):not(.circle):hover::before {
    background: rgb(240, 128, 128) !important;
}

.cell {
    width: 100px;
    height: 100px;
    border: 2px solid beige;
    display: flex;
    justify-content: center;
    align-items: center;
    position: relative;
    }

.cell:nth-child(1),
.cell:nth-child(2),
.cell:nth-child(3){
    border-top: none;
}

.cell:nth-child(1),
.cell:nth-child(4),
.cell:nth-child(7){
    border-left: none;
}

.cell:nth-child(3),
.cell:nth-child(6),
.cell:nth-child(9){
    border-right: none;
}

.cell:nth-child(7),
.cell:nth-child(8),
.cell:nth-child(9) {
    border-bottom: none;
}

.cell.x,
.cell.circle {
    cursor:  not-allowed;
}

/* X */
.cell.x::before,
.cell.x::after,
.board.x .cell:not(.x):not(.circle):hover::after,
.board.x .cell:not(.x):not(.circle):hover::before {
    content: "";
    height: calc(100px * 0.15);
    width: calc(100px * 0.9);
    background: beige;
    position: absolute;
}

.cell.x::before,
.board.x .cell:not(.x):not(.circle):hover::before {
    transform: rotate(45deg);
}

.cell.x::after,
.board.x .cell:not(.x):not(.circle):hover::after {
    transform: rotate(-45deg);
}

/* CIRCLE */
.cell.circle::before,
.cell.circle::after,
.board.circle .cell:not(.x):not(.circle):hover::after,
.board.circle .cell:not(.x):not(.circle):hover::before {
    content: "";
    height: calc(100px * 0.9);
    width: calc(100px * 0.9);
    background: beige;
    position: absolute;
    border-radius: 50%;
}

.winning-message {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    justify-content: center;
    align-items: center;
    background-color: rgba(0, 0, 0, 0.4);
    flex-direction: column;
}

.winning-message-button {
    font-size: 2.5rem;
    background-color: rgba(65, 185, 131, 1);
    padding: 10px 15px;
    cursor: pointer;
    border-radius: 5px;
    border: none;
    margin-top: 350px;
    color: white;
}

.winning-message-button:hover {
    color: black;
    background-color: beige;
}

.winning-message-text {
    color: white;
    font-size: 5rem;
}

.show-winning-message {
    display: flex;
}