*, *::after, *::before{
    box-sizing: border-box;
}

:root{
    --cell-size:100px;
    --cell-height:100px;
    --mark-size:calc(var(--cell-size) *.9);
}
body{
    margin:0;
    background-color: #FFF5EE;
}
p{
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    text-align: center;
    font-size: 20px;
    color:#4B0082;
}
.instruction{
    color:#33006F;
    font-weight: bold;
}

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

.cell {
    width:var(--cell-size);
    height: var(--cell-height);
    display: flex;
    border:1px solid black;
    justify-content: center;
    align-items: center;
    position: relative;
    cursor: pointer;
}

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

.cell.x::before,
.cell.x::after{
    background:#13274F ;
}

.cell.circle::before{
    background-color: #5A4FCF;
}
.board.circle .cell:not(.x):not(.circle):hover::before{
    background-color: #CCCCFF;
}

.board.x .cell:not(.x):not(.circle):hover::before,
.board.x .cell:not(.x):not(.circle):hover::after{
   background-color: lightblue;
}

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

.cell:nth-child(3n + 1){
    border-left: none;
}

.cell:nth-child(3n + 3) {
    border-right: none;
}

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

.cell.x::before,
.cell.x::after,
.board.x .cell:not(.x):not(.circle):hover::before, 
.board.x .cell:not(.x):not(.circle):hover::after{
    content: '';
    position:absolute;
    width:calc(var(--mark-size) * .15);
   
    height: var(--mark-size);
   
}

.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);
}

.cell.circle::before,
.cell.circle::after,
.board.circle .cell:not(.x):not(.circle):hover::before, 
.board.circle .cell:not(.x):not(.circle):hover::after {
    content: '';
    position:absolute;
    border-radius: 50%;
    width:var(--mark-size);
    height: var(--mark-size);
   
}

.cell.circle::before,
.board.circle .cell:not(.x):not(.circle):hover::before{
    width: var(--mark-size);
    height: var(--mark-size);
    
}

.cell.circle::after,
.board.circle .cell:not(.x):not(.circle):hover::after{
    width: calc(var(--mark-size) * .8);
    height:calc(var(--mark-size) * .8);
    background-color: #FFF5EE;
}

.winning-message{
    display:none;
    position:fixed;
    top:0;
    left:0;
    right:0;
    bottom:0;
    background-color: rgba(175,219,245, .9);
    justify-content: center;
    align-items: center;
    color:#1a1f71;
    font-size:5rem;
    flex-direction: column;
}
.winning-message button{
    font-size:3rem;
    background-color: #13274F;
    border:1px solid transparent;
    border-radius: 40px;
    padding: .25em .5em;
    cursor: pointer;
    color:#1da1f2;
}

.winning-message button:hover{
    background-color: #1da1f2 ;
    color:#13274F;
}

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


@media only screen and (max-width: 768px) {
    .p{
        display:flex;
        align-items: center;
        justify-content: center;
    }
    .board{
        width:100%;
     
    }
}